Open access peer-reviewed chapter

The Effects of Vitamin D Deficiency on Neurodegenerative Diseases

Written By

Anna A. Lauer, Daniel Janitschke, Tobias Hartmann, Heike S. Grimm and Marcus O.W. Grimm

Submitted: 05 August 2019 Reviewed: 13 August 2019 Published: 30 October 2019

DOI: 10.5772/intechopen.89160

From the Edited Volume

Vitamin D Deficiency

Edited by Julia Fedotova

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Abstract

Approximately 90% of the elderly population in the western countries has at least a mild to moderate vitamin D hypovitaminosis. Besides the well-known function of vitamin D in calcium homeostasis, it has been recently found that several enzymes and receptors involved in its homeostasis are expressed in the nervous system and brain suggesting also an important role in the brain homeostasis. Interestingly, epidemiological and clinical studies found reduced vitamin D level associated with an increased risk of several neurodegenerative disorders. In this chapter, we focus on a potential link between vitamin D and Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, prion disease, and motor neuron disease. Epidemiological studies were summarized, an overview of the known potential underlying pathomolecular mechanisms are given, and results from clinical studies dealing with vitamin D supplementation were presented. As an outlook, recent literature suggesting an impact of vitamin D on autism spectrum disease, depression, and schizophrenia are briefly discussed. In conclusion, the identification of an abundant vitamin D metabolism in the brain and the tight link between the increasing number of several neurological and mental disorders emphasize the need of further research making a clear recommendation of the intake and supplementation of vitamin D in a growing elderly population.

Keywords

  • vitamin D hypovitaminosis
  • Alzheimer’s disease
  • Parkinson’s disease
  • multiple sclerosis
  • prion disease
  • neuropsychiatric diseases

1. Introduction: relationship between vitamin D and neurodegenerative diseases

The secosteroid vitamin D3 was identified in the year 1928 by Adolf Windaus and colleagues. Its synthesis starts in the skin based on 7-dehydrocholesterol through extraneous cause of ultraviolet B radiation in a spectrum of 290–315 nm wavelengths. Via the vitamin D-binding protein, it is transported in the blood to the liver where the 25-hydroxylase CYP2R1 hydroxylates vitamin D3 to 25-hydroxyvitamin D3 (25(OH)D3). Because of its serum half-life of weeks, this 25-hydroxylated form of vitamin D3 is clinically measured as an indicator for the patients’ vitamin D3 level [1, 2]. The active form of vitamin D3, 1,25-dihydroxyvitamin D3 (1α,25(OH)2D3) or calcitriol, is synthesized in the kidney by the 1α-hydroxylase CYP27B1. To a limited extent, vitamin D3 can also be taken up with diet as well as vitamin D2 (ergo-calciferol), which is largely found in food.

Calcitriol can perform its genomic actions via vitamin D receptor (VDR) binding. Hence this undergoes a conformational change and forms a complex with the retinoid X receptor (RXR) which interacts with the vitamin D response element (VDRE) to regulate the expression of numerous genes. Because of this ability of transcriptional modulation, vitamin D has influence on various cellular processes, for example, the mitochondrial function by maintaining the mitochondrial respiratory chain activity [3]. Dysfunctional mitochondria will normally be removed by autophagy, a process that is also promoted by vitamin D [4]. Damaged mitochondria could induce inflammation. Vitamin D is able to downregulate the expression of pro-inflammatory cytokines such as the tumor necrosis factor-α (TNF-α) or interleukin-6 (IL-6), thereby reducing inflammation [5]. Additionally to these cellular processes, vitamin D antagonizes oxidative stress by enhancing the expression of antioxidants and thereby reduces levels of reactive oxygen species (ROS) [6]. Furthermore the expression of the voltage sensitive L-type Ca2+ channels is suppressed by vitamin D to regulate intraneural calcium [7, 8]. Vitamin D also plays a role in DNA-related cellular processes, for example, epigenetic changes. These are influenced on the one hand by oxidative stress which is regulated by vitamin D, as described before, and on the other hand by histone methylation which is also modulated by vitamin D due to its influence on the transcription of key DNA demethylases [9, 10].

Based on the fact that up to 90% of the elderly population is suffering from a vitamin D hypovitaminosis because of a homebound lifestyle and the reduced ability of their skin to generate vitamin D3, the idea arose to analyze the impact of a vitamin D deficit on the abovementioned cellular processes which are all involved in ageing [11]. Moreover, ageing is a risk factor for neurodegenerative disorders. Michael J. Berridge published a very detailed article 2 years ago reviewing the influence of vitamin D deficiency on ageing and age-related diseases. He figured out that hypovitaminosis D promotes those ageing-related processes, for example, due to a decline of mitochondrial respiration or the electron transport chain. This dysfunction leads to an increase in oxidative stress and inflammation, main drivers of ageing. Furthermore, he describes elevated Ca2+ levels in neurons during ageing which are accompanied by a decline in cognition. This observation can be restored by vitamin D due to its ability to reduce the levels of Ca2+. Additionally, telomere shortening, a DNA-related process that is involved in ageing, is reported to be decreased by vitamin D [12]. Those upregulated ageing processes under vitamin D-deficient conditions in the elderly population could further lead to age-related disorders like dementia or declines in cognition.

A relationship between vitamin D and age-related cognitive disorders was further strengthened by the findings that vitamin D and its metabolites are able to cross the blood-brain barrier. Early research reported the presence of vitamin D metabolism intermediates and products in human cerebrospinal fluid [13]. Furthermore, due to the presence of the metabolizing hydroxylases in the brain, the active form of this hormone-like secosteroid can be synthesized in the human brain. The additive existence of the VDR in neuronal and glial cells suggests that vitamin D might influence functioning of the central nervous system (CNS) [14]. As mentioned earlier, the VDR-mediated nuclear functions of 1,25(OH)2D3 influence cellular processes, for example, immune modulation and cell growth or differentiation. Those biological systems have also an impact on maintaining the function of the brain. Annweiler et al. reported increased risks of cognitive disorders for patients with 25(OH)D3 serum concentrations lower than 10 ng/ml [15]. Vitamin D influences the structure of the brain, like changes in volume and vasculature as well as its metabolism [16]. Furthermore, in vivo studies using offspring of vitamin D-deficient rats could show that vitamin D plays an important role in the developing brain [17]. Eyles et al. give a detailed overview in their review over all the different animal studies that have been made in this context. One exemplary finding is that rats with a vitamin D deficiency during their development have impairments in their adult behavior [18].

In a retrospective study from 2007, Przybelski and colleagues reported that serum 25(OH)D3 can be positively associated with increased cognitive function [19]. Consistent finding results from a prospective cohort study in older adults that showed a vitamin D hypovitaminosis (levels <30 ng/mL) in 68% of the participants and moreover that these ones have lower baseline cognitive function and increased decline over the 4 years of follow-up [20]. In the same year, another prospective study including 1185 women also pointed out an association of higher plasma 25(OH)D3 levels and better cognitive performance [21]. A meta-analysis showed that participants with insufficient vitamin D levels have a 2.4-fold increased risk of cognitive impairments than those with sufficient levels [22]. In line with this, further systematic reviews and meta-analysis support an association between hypovitaminosis D and declined cognitive functions [23, 24]. Additionally, some longitudinal studies suggest a link between low serum 25(OH)D3 levels and cognitive performance. Toffanello et al. reported decreasing scores at Mini-Mental State Examination (MMSE) in participants having serum 25(OH)D3 levels below 75 nmol/L in their 4.4-year follow-up study including 1927 elderly subjects [25]. One year later, Miller et al. published a vitamin D-associated accelerated decline in cognitive performance in their study of a multiethnic cohort of older adults [26]. In line with these data, a more recent clinical study in the elderly US population (3325 participants) reported that low serum levels of vitamin D3 are linked to an enhanced risk of cognitive impairment [27].

Due to the suggested role of vitamin D in brain function, several studies examining the effect of dietary supplemented vitamin D exist. Animal studies and epidemiological studies generate biological evidences for a relationship between vitamin D levels and brain health. Latimer et al. could show that a 6-month supplementation of vitamin D improves cognitive function in a rat model of aging [28]. One study from Annweiler and colleagues in the year 2010, including 5596 women with a mean age of 80.5 years, concluded that higher weekly dietary vitamin D intake is associated with better cognitive performance in older adults [29]. In line with this, a current cross-sectional and longitudinal study describes a significant association between serum vitamin D levels below 30 nmol/L and reduced general cognitive performance [30].

Unlike those animal and epidemiological findings, clinical studies using randomized controls examining the role of vitamin D in individuals without any form of dementia show heterogeneous data [31, 32, 33, 34]. In general, it should not be disregarded that differences in clinical intervention studies might be because included participants who already had sufficient vitamin D levels at baseline could mask the benefit of supplementation on cognitive function. To prevent this, it would be beneficial including exclusively participants affected by a hypovitaminosis D at the baseline measurement. These inconclusive data also support the idea of individually adjusted supplementation protocols for each patient. Furthermore, methodological differences between the studies, for example, duration, form, and dose of vitamin D supplementation, have to be considered. A current study from Pettersen et al. [35] considered these abovementioned methodological pitfalls by administering 4000 IU/day of vitamin D3 for 18 weeks to healthy adults and by baseline as well as endpoint measurements of serum 25(OH)D3 levels. Furthermore, they were able to distinguish between the two cognitive domains, verbal and visual memory, with several cognitive tests. High doses of vitamin D enhanced visual memory, while low doses (400 IU/day) improved verbal memory. As summarized by the authors, there seems to be a small positive effect of vitamin D3 supplementation on executive functioning, despite the outlined limitations (modest sample size with wide range of ages, no true placebo group) [35]. Recently, Aspell et al. give a well elaborated overview over a possible supporting role of vitamin D in cognitive function in age [36]. In the following chapter, we will present the results of current available studies examining the impact of vitamin D supplementation on brain-related disorders for each neurodegenerative disease itself. Up to this date, also the nutrition research field examines the influence of dietary components on brain health. In a recent review from Moore et al., the authors describe a potential protective role for vitamin D among others [37].

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2. Alzheimer’s disease

Alzheimer’s disease (AD) can be described as a multifactorial, metabolic disease as this disease is characterized by impairments in multiple cellular processes. For example, AD pathology includes alterations in the sequential proteolytic processing of the amyloid precursor protein (APP) which results in the formation of neurotoxic Aβ plaques, in the phosphorylation of the microtubule-associated protein Tau, in lipid and energy metabolism, and in inflammation. Among others, AD pathogenesis is influenced by lipophilic vitamins [38].

Epidemiological studies indicate a relationship between vitamin D deficiency and AD. A systematic review and meta-analysis concluded that patients affected by AD have lower levels of serum 25(OH)D3 than healthy controls [39]. Furthermore the level of vitamin D is shown to be significantly reduced in the cerebrospinal fluid of AD patients [40]. Another meta-analysis from Shen and colleagues shows that vitamin D hypovitaminosis (25(OH)D3 level < 50 nmol/L) is associated with a 21% increased risk of AD [41]. Different results were obtained by a study, measuring serum level of 25(OH)D3 via radioimmunoassay in patients with MCI or diagnosed dementia compared to healthy controls. Analysis of the cognitive performance showed significant differences between these groups. Vitamin D levels of 65.2 ± 17.9 nmol/L for controls, 61.4 ± 18.8 nmol/L for MCI, and 65.0 ± 20.3 nmol/L for AD were reported in this study; however the differences in vitamin D concentrations between these groups were not statistically significant. Interestingly, the authors show that approximately 12% of the MCI and AD patients used some kind of vitamin D supplementation, whereas only 5% of healthy controls did so. Furthermore, 80% of the MCI patients, 50% of the AD patients, and 62% of the control individuals regularly used nutritional supplements, which could have influenced the results as discussed by the authors. In conclusion, the authors comment that their “findings cannot exclude the possibility that targeted vitamin supplementation can act as a modifying measure, although it is less likely that vitamin intake can prevent dementia onset” [42].

Several longitudinal studies provide homogeneous results indicating that a deficiency in serum 25(OH)D3 is linked to a greater risk and incidence of dementia and AD [43, 44, 45, 46, 47]. A current prospective study analyzed 25(OH)D3 level, cognitive decline, and incidence of dementia in 916 patients for 12 years and reported a more pronounced cognitive decline and a threefold increased risk of AD in individuals with hypovitaminosis D [48].

In line, a study from 2018 analyzing the serum vitamin D level in AD patients described decreased levels in various stages of AD. Additionally, the authors indicate 25(OH)D3 as significant predictor for severe AD and argue for vitamin D supplementation in AD patients [49]. Moreover, Wang et al. recently reported a delayed onset of psychotic symptoms when vitamin D was used in AD patients and suggest variations in vitamin D-influenced genes as biomarkers for those individuals who can have a benefit from supplementation [50].

These studies consistently indicate a link between insufficient dietary intake of vitamin D and cognitive diseases like AD. However, these studies did not address the question whether vitamin D deficiency is a cause and thus risk factor for AD or a consequence of this neurodegenerative disease mediated by accompanying dietary and behavioral changes. Some more evidence of a causal relationship between hypovitaminosis D and AD was achieved by Mendelian randomization (MR) studies that use genetic associations on inherited alleles unaffected by confounding factors or disease progression. It was reported that two polymorphisms in the VDR gene are associated with AD risk in patients younger than 76 years [51]. A subsequent meta-analysis including six AD studies also revealed this relationship [52], as well as an earlier study using genotyping of 213 participants [53]. Wang et al. also provide this genetic evidence and could further generate functional data indicating a link between the VDR and the genetic AD risk [54]. Furthermore, the study of Mokry and colleagues supports genetically decreased vitamin D levels as causal risk of AD, by analyzing the effect of single-nucleotide polymorphisms (SNPs) involved in vitamin D metabolism on 25(OH)D3 levels and the risk of AD in more than 56,000 participants [55]. A recently published MR study from Larsson and colleagues including 17,008 AD cases and 37,154 controls reported an inverse association between 7 SNPs related to elevated vitamin D3 levels with AD, in which 2 of them were significant [56]. A study creating a vitamin D synthesis risk score analyzing more than 1000 Swedish men in a follow-up of 18 years is controversially discussed as this study revealed no link between baseline vitamin D status and the long-term risk of dementia [57].

Concerning clinical studies, randomized placebo-controlled trials analyzing the effect of vitamin D supplementation on AD risk and progression are still missing. However, recently nonrandomized studies showed positive findings about that relationship. A current study reported improvements in the cognitive status of MCI patients (n = 16) in an 18-month follow-up after 6 months of vitamin D supplementation. Additionally, vitamin D supplementation protected lymphocytes from oxidative stress [58].

In contrast to the missing clinical trials, several animal and cell culture studies underline a causal relationship between vitamin D and AD. One study described an increased neurogenesis and enhanced cognition after feeding a transgenic mouse model of AD (5xFAD mouse model) with a daily dose of 500 IU/kg vitamin D for 5 months [59]. Additionally, animal and cell culture studies allow analyzing combination therapies, for example, a supplementation of both vitamin D and resveratrol. This resulted in an improvement of cognitive function and reduced levels of Aβ42 in the hippocampus along with decreased tau phosphorylation in the parietal cortex of a mouse model with AD-related memory impairment [60]. In line, a novel study from 2019 reported an improvement of the AD-related pathology in 5xFAD mice after intravenous injection of vitamin D-binding protein which was loaded on a biocompatible polymer (PLGA) [61]. Especially cell culture and animal-based studies are indispensable for clarifying the molecular mechanisms of vitamin D action in neurodegenerative diseases. They revealed that vitamin D exerts its protective effects via VDR-related, genomic, as well as non-genomic actions directed to processes like Aβ metabolism, neurogenesis, immune modulation, and neuronal calcium homeostasis. A study from Landel et al. examined the transcriptome of 5xFAD mice after 5 months of vitamin D3 supplementation and reported a large number of differentially expressed genes. The authors suggest an interaction of vitamin D with estrogen and insulin signaling to regulate the identified pathways [62]. Consistently, we could show that a deficit of vitamin D causes a dysregulation of numerous genes that are involved in multiple cellular processes like neurogenesis, inflammation, mitochondrial function, oxidative stress, signal transduction, and APP homeostasis in brains of hypovitaminosis D mice [63]. In respect to the impaired APP homeostasis, several studies using primary cortical neurons or human neuroblastoma cell lines were able to show beneficial effects of vitamin D and its analogues on anabolism and catabolism of the neurotoxic Aβ peptide [64, 65]. In line with these findings, a vitamin D3-enriched diet leads to an increased Aβ clearance in mouse models of AD [66, 67, 68]. Consistent with the results of animal studies, Hooshmand et al. could demonstrate an association of increased plasma 25(OH)D3 levels with higher concentrations of CSF Aβ1-42 in 75 patients, reflecting a decreased Aβ1-42 aggregation in human brain parenchyma [69]. In contrast, a recent cross-sectional study failed to find significant associations between plasma vitamin D levels at baseline and Aβ load in different brain regions. But the authors themselves argue that those findings could be explained by an improper timing of measurements or rather no analysis over time or by a hypovitaminosis D-related cognitive decline independent of APP homeostasis [70]. The potential neuroprotective role of vitamin D3 is based on findings that it regulates the transcription of the neurotrophin nerve growth factor, glial-derived nerve factor, and neurotrophin 3 which are important for neuronal survival [71, 72, 73]. Furthermore, the expression of the neuroprotective cytokine IL-34 was shown to be increased in dose- and time-dependent manner by calcitriol in neuroblastoma cells [74]. In respect to a relationship between vitamin D and neuronal calcium levels, a review describes a reduced autophagy due to impairments in calcium signaling as a consequence of hypovitaminosis D [6].

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3. Parkinson’s disease

As one of the most common neurodegenerative diseases, Parkinson’s disease (PD) is characterized by the loss of dopamine-producing neurons in the substantia nigra pars compacta and typical Lewy bodies, aggregates of α-synuclein, provoking oxidative stress and further cell death, leading to impairments in cognition and behavior and to dysautonomia [75].

A number of epidemiological studies were able to indicate an association of vitamin D and PD. Several evidences exist that hypovitaminosis D is more frequent in PD patients [76, 77], and a cohort study with a 29-year follow-up reported a decreased risk of PD in individuals with higher vitamin D serum levels [78]. These findings are supported by the outcomes of recent studies describing significantly reduced levels of serum 25(OH)D3, daily vitamin D intake, and sunlight exposure in PD patients [79]. Besides significantly decreased serum 25(OH)D3 levels, also an association of vitamin D at baseline and disease motor severity after 36 months was observed in a recently published prospective observational study [80]. A clinical study found an inverse relationship between serum vitamin D concentrations and disease severity as well as an influence on balance function in PD patients [81]. A current study reported that vitamin D status of PD patients has no influence on nocturnal changes in blood pressure, a marker of cardiac autonomic dysfunction as non-motor symptom in PD [82]. However, the tight link between serum vitamin D concentrations and risk as well as severity of PD is also underlined by a recent systematic review and meta-analysis of Luo et al. [83].

PD is not only caused by environmental factors, for example, the vitamin D status, but also by genetic components. The first monogenetic mutation, which was found to be associated with early onset familial PD, is located in the SNCA gene that encodes the α-synuclein protein [84]. A recent study was able to show an altered expression of Snca in brains of vitamin D-deficient mice, underlining a causal relationship between hypovitaminosis and PD [63]. Consistent with several previous publications, this is also supported by two recent studies analyzing SNPs in VDR and the vitamin D-binding protein. Besides the functional VDR polymorphism, FokI was reported to be associated with cognitive decline in PD and ApaI with the risk of PD, while vitamin D-binding protein gene was suggested as a risk factor for PD [85, 86]. In line with this, a double-blind, placebo-controlled intervention study from Suzuki and colleagues, including 114 PD patients, was able to reveal that supplementation of 1200 IU vitamin D3/day prevents disease progression in a VDR FokI genotype-dependent manner [87]. Moreover, high-dose supplementation of vitamin D (10,000 IU/day) resulted in significant improved balance measured via sensory organization test in PD patients with an age of 52–66 but not in older individuals [88].

To elucidate the underlying molecular mechanisms by which vitamin D exerts its potential beneficial role, animal and cell culture experiments were performed. Vitamin D3 seems to have a positive influence on synthesis and storage of dopamine in CNS by protecting against dopaminergic toxins such as 6-hydroxydopamine or hydrogen peroxide in rats [89]. This neuroprotective effect could be due to its ability to elevate the expression of the glial cell line-derived neurotrophic factor (GDNF) that influences the dopaminergic nigrostriatal system [90] and due to its antioxidative properties described before. Furthermore vitamin D3 administration was shown to prevent zinc-induced oxidative stress in substantia nigra of rat brain [91]. Oxidative stress and elevated intracellular-free calcium promote the aggregation of α-synuclein synergistically, and a recent study could show that the vitamin D3 analogue calcipotriol is able to induce the expression of calbindin-D28k, thereby inhibiting the calcium-mediated aggregation of α-synuclein in human neuroblastoma cells [92].

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4. Multiple sclerosis

Multiple sclerosis (MS) is a multifactorial, chronic disease of the CNS characterized by demyelination, inflammation, and neurodegeneration.

Epidemiological studies indicate that genetic and environmental factors interact and influence the risk of MS, for example, several SNPs or environmental exposures like an infection with Epstein-Barr virus (EBV), vitamin D status, sunlight exposure, or smoking. There is a high prevalence for MS in areas with low sun/ultraviolet sun exposure [93, 94], and this could be explained by vitamin D [95]. A study from Lucas and colleagues revealed that vitamin D and sun exposure are independent risk factors of CNS demyelination [96]. For an overview over environmental factors and MS, we suggest an article from Ebers GC [97]. Genetic predispositions which are associated with MS are found in genes of the immune system. The strongest correlation was found for genes of the major histocompatibility complex (MHC), especially the HLA genotype HLA-DRB1 [98]. Findings from Ramagopalan and colleagues suggest a direct functional link between known environmental risk factors, for example, vitamin D, and established genetic predispositions. The authors described the localization of a vitamin D response element on the promotor region of HLA-DRB1 and underlined its functional role by the finding that treatment with calcitriol results in an increased expression [99]. Later on this research group could show that mutations in the CYP27B1 gene, involved in vitamin D3 metabolism, are causative associated with the risk of MS [100]. Moreover, genetic variations in the CYP24A1 gene, involved in catabolism of vitamin D, were found to play a pathogenic role in MS [101]. For detailed information about the results of several genome-wide association studies analyzing the genetic risk of developing MS, we recommend a recent publication from Baranzini and Oksenberg [102].

Clinical studies indicate that vitamin D influences MS development and disease activity including the risk of relapse, gray matter volume loss, and clinical course of MS. A prospective study from Munger et al. included participants from the US military personnel and reported a significantly decreased risk of MS with elevated levels of 25(OH)D3 [103]. Furthermore, a cross-sectional study described a link of serum 25(OH)D3 levels with both relapse rate and disability in MS patients [104]. In line with this, an association of reduced serum 25(OH)D3 levels with a higher risk of relapse in MS was reported in a prospective longitudinal study including 73 individuals with relapsing-remitting MS [105]. Consistent findings are obtained from a retrospective study describing an association of a 10 ng/ml increase in 25(OH)D3 level with a 34% reduced relapse rate in pediatric-onset MS [106] and from a prospective study reporting a 25(OH)D3 elevation of 10 nmol/L to be associated with a 12% decreased risk of relapse in a cohort including 145 participants [107]. A 5-year longitudinal study from Mowry and colleagues using magnetic resonance imaging (MRI) as marker of disease activity provided evidences for a lower risk of developing new T2 lesions and gadolinium-enhancing lesions as well as reduced subsequent disability attended by an 10 ng/ml increase in 25(OH)D3 level [108].

As mentioned before in the context of AD, these clinical studies are not able to rule out the possibility of reverse causality. In this context MR studies are of great interest analyzing this potential causal relationship of vitamin D and MS risk. Mokry et al. identified four 25(OH)D3 level-associated SNPs in a large genome-wide association study for vitamin D, called SUNLIGHT, and performed an MR study to examine the influence of genetically reduced vitamin D3 levels on the odds of MS in a large genetic association study for MS. This leads to the finding that genetically reduced vitamin D3 levels are strongly linked to an elevated MS risk [109]. This thesis is furthermore supported by another novel MR study that described causal effects of decreased vitamin D3 levels on pediatric-onset MS [110]. A very recent study from Graves et al. provides evidence for a causal link between 25(OH)D3 and MS relapses in children. The authors indicate that a vitamin D genetic risk score (vitDGRS) can support the identification of patients at greater relapse risk [111].

The protective role of vitamin D could be exerted on the molecular level mainly due to its several potential immunomodulatory effects. These are summarized in a review from Smolders and colleagues. The authors pointed out that vitamin D causes a shift to an anti-inflammatory immune response and increased regulatory T cells as well as reduced pro-inflammatory helper cells like Th1 and Th17 selectively [112]. In line with this, a study from Munger et al. reported an overlap of genes associated with vitamin D3 and those associated with processes of immune regulation. Furthermore they suggest the sphingosine-1-phosphate receptor-dependent migration of lymphocytes from secondary lymphoid tissue as potential vitamin D3-mediated mechanism [113]. Additional evidences for the MS-underlying molecular mechanisms arise from a recent study using the L-type calcium channel antagonist nimodipine, showing decreased neurodegeneration in experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. The authors reported calcium channel-independent, microglia-specific effects: induction of apoptosis, reduced levels of NO and ROS, as well as positive effects on remyelination [114].

Based on the results of all these studies demonstrating a causal link between vitamin D hypovitaminosis and the risk of MS, the role of vitamin D3 supplementation in MS therapy was investigated. A study from Munger et al. reported an approximately 41% reduced relative risk of MS due to the supplementation of 400 IU vitamin D/day in two large cohorts of women [115]. Several following studies also describe beneficial effects of vitamin D3 supplementation on gadolinium-enhancing lesions, relapses, and T-cell proliferation without unrequested calcemic side effects [116, 117, 118]. Inconsistent with these results, another study revealed no positive effect of high-dose vitamin D3 supplementation (20,000 IU/week) on course and activity of the disease, for example, the relapse risk. A possible explanation for this finding could be individuals with high vitamin D3 levels in the placebo group. Furthermore the authors could not preclude that the used vitamin D dose was too low or that the sample size was too small [119]. In this context it should be mentioned that the individual vitamin D metabolism, which could be influenced by genetically mutations in the enzymes required for the anabolism and catabolism of vitamin D3 as discussed before, has to be analyzed since this would influence the response to identical supplemented doses of vitamin D in different individuals [120]. Subsequent studies were able to show a reduction in relapse rate after supplementation of vitamin D3 [121] and an improved cognitive performance [122]. Oral supplementation of 20,000 IU vitamin D3/week in a 96-week randomized double-blind placebo-controlled study in 68 MS patients results in reduced levels of anti-EBV nuclear antigen 1 (EBNA1) protein and fragment antibody [123]. A previous study could show a remarkable overlap of EBNA2 with VDR binding sites and thereby demonstrates a genetic argument for an interaction between genetic and environmental risk factors of MS [124]. A current study reports that long-term supplementation for several months with high doses of cholecalciferol results in a significantly promoted aggravation of clinical and histological EAE, but simultaneously they find a direct, anti-inflammatory, beneficial effect of vitamin D on lymphocytes of human and murine origin [125].

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5. Prion diseases

Prion diseases are a group of neurodegenerative disorders whose pathology is caused by the conversion of the cellular prion protein (PrPC) into a misfolded form of the protein, called prion or “scrapie prion protein” (PrPSc), a proteinaceous, insoluble, infectious particle which is resistant to proteases and seems to act as template for exponential transformation and further accumulation of prion proteins. One characteristic of prion diseases is their appearance by sporadic (spontaneously conversion, Jakob-Creutzfeldt disease), genetic (familial mutations in the prion protein gene, PRNP), or acquired (accidentally transmission or infection) mechanisms [126].

A study on transgenic mice was able to identify a naturally occurring polymorphism in the human PRNP which is very rare but seems to completely prevent prion disease [127]. Up to this date, no clinical trial on human prion disease was successful, and most of the analyzed chemical compounds failed as potential therapeutics because of their toxicity. A study from Suenaga and colleagues intended to identify compounds that interfere with the direct PrPC-PrPSc interaction by screening hydrophobic vitamins. The authors reported for the first time that vitamin D2 was able to interact with a truncated form of human recombinant PrPC leading to a reduced oligomerization in vitro. The absence of such an effect mediated by vitamin D3 could be due to structural differences between these two vitamin D forms. This study suggests vitamin D2 as suitable therapeutic candidate to target PrPC in the brain of patients with prion disease because of its direct inhibition of PrPC oligomerization, its blood–brain barrier permeability, and its safety compared to other synthetic compounds [128]. But apart from that, more studies, especially clinical trials, are essential to elucidate the relationship of vitamin D and prion diseases.

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6. Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects upper and lower motor neurons in the brain and spinal cord resulting in paralysis [129]. It is characterized, similar to the abovementioned vitamin D3-associated diseases, by oxidative stress, inflammation, mitochondrial dysfunction, and neurodegeneration [130].

Clinical studies result in inhomogeneous findings about a possible role of vitamin D on ALS. A retrospective study including 57 ALS patients reported neither significant differences in 25(OH)D3/D2 blood levels in comparison to 57 healthy individuals nor an improvement of the recorded clinical, ALS-related variables after oral supplementation of 100,000 IU of vitamin D3/week for 4 weeks and thereafter 25,000 IU every 15 days compared to untreated participants. But as discussed by the authors, potential limitations of this study are its retrospective character and the sample size [131]. Two earlier studies also described an absent relationship between serum 25(OH)D3 levels and prognosis in ALS [132, 133]. A very recent study examined the outcome of supplementation of 50,000, 75,000, and 100,000 IU vitamin D3/month on motor dysfunction and clinical progression of ALS. After 6 months, they reported increased levels of serum 25(OH)D3 from approximately 14 ng/mL at starting point to approximately 40 ng/mL after supplementation of 75,000 and 100,000 IU vitamin D3 monthly, but there were no statistically significant differences in the tested clinical ALS characteristics. As the authors mention, the sample size of 10–12 participants per group as well as the short duration of the follow-up study has to be taken into consideration [134].

In contrast to these findings, a study from Karam et al. reported vitamin D level less than 30 ng/mL for 81% of their patients with ALS and additionally improvements in the Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) score after supplementation of 2000 IU vitamin D/day for 9 months in 20 participants [135]. In line, a subsequent study described a neuroprotective role for the biologically active form of vitamin D3 as well as a four-time accelerated decline and reduced expectation of life due to hypovitaminosis D [136]. These variable outcomes strengthen the need of further clinical studies with an adequate sample size to reach statistical power and follow-up period analyzing the effect of vitamin D3 on ALS. A first evidence of a genetic link between vitamin D3 and ALS arises from a study from Török and colleagues describing that a SNP in the VDR gene is associated with ALS [137]. Further suggestions of a potential role of the VDR in ALS derived from the finding that VDR-knockout mice have muscular and motor disruptions but no reduced cognitive performance [138].

In contrast to the ambiguous clinical studies, animal trials provide evidences for a positive effect of supplemented vitamin D3 on ALS. Studies from Gianforcaro and colleagues reported beneficial functions of high-dose dietary vitamin D3 supplementation on the paw grip endurance and motor performance of transgenic G93A ALS mouse model while decreased performance of functional outcome in vitamin D3 deficient mice [139, 140].

In reference to the above itemized similarities in ALS characteristics with other neurodegenerative diseases, it is not remarkable that the molecular mechanisms of which vitamin D3 is suggested to have a beneficial influence on ALS are overlapping. Vitamin D3 could decrease the elevated levels of TNF-α or IL-6 found in ALS patients [141] or influence calcium metabolism by regulating the expression of calcium-binding proteins, known to be impaired in ALS [142]. More detailed information can be found in the publications from Gianforcaro et al. and Long et al. [143, 144].

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7. Huntington’s disease

Up to this date, only a few studies are available examining a possible relationship between vitamin D3 and Huntington’s disease (HD), a neurodegenerative disorder characterized by impairments in cognition, motor behavior, and psychiatrics. HD is caused on molecular level by an expansion of an autosomal dominantly inherited CAG trinucleotide repeat in the huntingtin (HTT) gene which is located on chromosome four in humans. This leads to the expression of a mutant huntingtin protein containing an abnormal long polyglutamine repeat [145]. The number of repeats is associated with the risk of developing HD [146]. A recent clinical review describes the consequences of mutant huntingtin on cellular level, including interferences in transcription and protein homeostasis as well as mitochondrial dysfunction and direct toxicity of the altered protein itself. This leads to a disruption in neuronal function and further cell death and neurodegeneration [147]. To our knowledge, there are no current epidemiological or clinical studies suggesting a relationship between vitamin D status and HD, just an explorative study from Chel and colleagues. They reported a high prevalence of deficient or insufficient serum vitamin D level (<50 nmol/L) in 28 individuals with manifest HD [148]. In line with this, a recent study on HD transgenic mice showed no effect on motor performance but a significantly prolonged lifespan after subcutaneous supplementation of 12,000 IU vitamin D3 per kilogram weight [149]. Further evidences for an influence of vitamin D3 on HD arise from a recent publication of Seuter and colleagues analyzing the epigenome-wide effects of vitamin D in THP-1 human monocytes. They identified 165 physiologically important target genes after supplementation of 1,25-dihydroxyvitamin D3 being one of them the HTT gene [150].

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8. Neuropsychiatric diseases

Beside neurodegenerative disorders also neuropsychiatric diseases affect the nervous system, and therefore we would like to give a brief summary of recent studies analyzing a possible influence of vitamin D on autism spectrum disorders (ASD), depression, and schizophrenia. Epidemiological studies demonstrated an elevated prevalence for ASD in children born at higher latitudes [151] and in offspring of highly pigmented women [152] as well as lower vitamin D levels of children with autism [153]. Furthermore maternal, gestational hypovitaminosis D is associated with a higher ASD risk [154, 155]. Recent findings of strong associations of ASD with polymorphisms in the VDR or other genes involved in vitamin D3 metabolism [156, 157] hypothesize vitamin D3 as environmental and genetic factor influencing ASD [158]. On the molecular level, cellular processes like oxidative stress or neuroinflammation were shown to play a role in ASD [159], and they could present a potential contact point for vitamin D3. In line with the abovementioned link between ASD and vitamin D, a vitamin D-deficient rat model revealed broad behavioral similarities between vitamin D-deficient models and ASD-associated behavior [160]. Treatment of an ASD rat model with high-dose vitamin D revealed significant protective effects [161]. In contrast to supplementation in animal trials, the first randomized controlled clinical study analyzing the daily supplementation of 300 IU vitamin D3/kg for 4 months on 109 children with ASD, resulting in significant improvement of autism symptoms, was retracted 1 month ago [162]. This lets us conclude that vitamin D3 can be suggested as possible preventive treatment for the prevention of ASD, but more studies supplementing pregnant women and their children with adequate levels of vitamin D3 have to be performed.

A potential link between vitamin D3 and depression is subject of current research, and for more detailed information about the potential role of vitamin D on major depressive disorder, we recommend a review from Casseb et al. [163]. A meta-analysis from Parker and colleagues concluded that there are increasing evidences for an influence of vitamin D on depression [164], and in line with this, another review also postulated hypovitaminosis D as risk factor for late-life depression [165]. Consistently, a very recent meta-analysis reported a negative association of serum 25(OH)D3 levels with the risk of depression [166].

A following cross-sectional study including 100 women in reproductive age also shows that the depression score inverse correlated with the vitamin D serum level [167]. Contradictorily, a supplementation with 1200 IU vitamin D for 12 months failed to have an influence on the prevention of depression in a very recent, randomized clinical trial including 155 participants having clinically relevant depressive symptoms [168]. Furthermore, a recent MR study from Libuda and colleagues indicates no causal relationship between both depressive symptoms and broad depression and vitamin D levels due to a missing association of six vitamin D-related SNPs with depression [169]. In summary, the current research investigating the role of vitamin D3 in depression is much less clear than other neurological disorders.

In respect to the chronic mental illness schizophrenia, it could be shown that hypovitaminosis D is common in patients [170]. This fits to the environmental risk factors that have been described for schizophrenia, like season of birth [171] and latitude [172]. Also a link between neonatal vitamin D levels and the schizophrenia risk was reported [173]. A recent randomized, placebo-controlled study from Krivoy and colleagues examined psychosis severity, mood, cognition, and metabolic profile in 47 schizophrenia patients during an 8-week supplementation of 14,000 IU vitamin D/week. The authors described no significant effects on psychosis, mood, or metabolic status, but a trend to an improved cognitive function accompanied by significant elevated vitamin D levels in the supplemented group. A possible explanation for these findings, given by the authors, could be that a medical score that measures the symptom severity in schizophrenia patients decreased during the study in the placebo as well as in the treated group and could thereby veil the influence of supplemented vitamin D [174]. An actual study reported beneficial effects of supplementation of vitamin D3 in combination with probiotics in schizophrenia patients [175]. Addressing the underlying molecular mechanism, vitamin D could perform its suggested beneficial actions via modulation of immune system and inflammation processes since it was reported that patients with chronic schizophrenia have significantly elevated levels of TNF-α and IL-6 [176]. Furthermore, it could be shown that the expression of genes involved in the metabolism of vitamin D3 (VDR, CYP27B1, CYP24A1) is significantly elevated in peripheral blood of schizophrenic patients [177], indicating a potential causal relationship between vitamin D3 and schizophrenia, which should be the aim of future research.

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9. Conclusion

In summary, in the current literature, several lines of evidence suggest a tight link between vitamin D3 and neurodegenerative diseases (see Table 1). Besides epidemiological studies, vitamin D deficiency influences several pathways associated with neurodegenerative diseases, which also indicates a causal link of hypovitaminosis D and AD, MS, and PD. As a consequence, vitamin D hypovitaminosis is broadly assumed to be a risk factor for these diseases. In addition, recent literature underlines a potential link between prion diseases, ALS, HD, and neuropsychiatric diseases and reduced Vitamin D level; however, it has to be emphasized that many aspects of vitamin D remain obscure in these diseases. Therefore, further studies to clarify and judge a potential beneficial effect of vitamin D3 are needed to unravel the exact role of vitamin D in brain metabolism and neurodegenerative diseases. Especially determination of the individual serum 25(OH)D3 levels by appropriate methods like mass spectrometry and taking the individual patient’s competence to metabolize or form active vitamin D3 into consideration will help to avoid ambiguous results. The fact that several prospective studies investigate a mixture of several different nutritional components makes it hard to trace the observed effects back to vitamin D in particular at the moment.

Alzheimer’s disease Parkinson’s disease Multiple sclerosis Prion disease Amyotrophic lateral sclerosis Huntington’s disease
Epidemiological and clinical studies Vit. D levels ↓ [39, 40]
Risk factor
[41, 43, 44, 45, 46, 47, 48]
Causal link
[51, 52, 53, 54, 55, 56]
Vit. D levels ↓ [76, 77, 78, 79]
Severity of PD [80, 81, 83]
Genetic link
[85, 86]
Risk factor
[96, 103]
Genetic predisposition [99, 100, 101]
Causal link
[109, 110, 111]
/ Non-consistent findings
[132, 133, 136]
Evidence of genetic link
[137]
Vit. D levels ↓ [148]
Animal and cell culture studies Causal link
[63]
Transcription
[62]
Causal relationship [63] Regulatory
T cells ↑
[112]
Vit. D2 as suitable therapeutic candidate
[128]
Potential role of the VDR
[138]
Benefits after supplementation
[139, 140]
Vit. D supplementation ↓ prolonged lifespan
[149]
Epigenomic action on HTT gene
[150]
Molecular mechanisms APP homeostasis [64, 65, 66, 67, 68, 69]
Neurotrophins
[71, 72, 73]
Inflammation
[74]
Ca2+ homeostasis [6]
Dopamine homeostasis
[89]
Antioxidative properties
[91]
Ca2+ homeostasis
[92]
Immunomodulatory effects
[113]
Ca2+ homeostasis [114]
Reduced oligomerization of prions
[128]
Inflammation [141]
Ca2+ homeostasis [142]
Potential transcriptional regulation of HTT gene
[150]
Intervention studies Beneficial
[58]
Beneficial in dependence of genotype
[87]
Beneficial
[115, 116, 117, 118]
Vit. D as genetic and environmental risk factor
[124]
/ Variable outcomes
[131, 134]
/

Table 1.

Summary of the current research findings about the influence of vitamin D on selected neurodegenerative diseases Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, prion disease, amyotrophic lateral sclerosis, and Huntington’s disease in respect to epidemiological and clinical, animal and cell culture studies, identified molecular mechanisms, and intervention studies.

Vit. D, vitamin D; APP, amyloid precursor protein; Ca2+, calcium; PD, Parkinson’s disease; VDR, vitamin D receptor; ↓ reduced.

Interestingly some European countries, like Finland, already supplement vitamin D in general in food to prevent hypovitaminosis in the elderly population, and an optimal intake of 2000–4000 IU vitamin D or 10–20 min sunlight exposure per day is already recommended by experts, for example, at the Joint International Symposium Vitamin D in Prevention and Therapy and Biologic Effects of Light (2019). Further studies will help to validate the beneficial effects of these recommendations.

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Conflict of interest

The authors declare no conflict of interest.

References

  1. 1. Datta P, Philipsen PA, Olsen P, Bogh MK, Johansen P, Schmedes AV, et al. The half-life of 25(OH)D after UVB exposure depends on gender and vitamin D receptor polymorphism but mainly on the start level. Photochemical & Photobiological Sciences: Official Journal of the European Photochemistry Association and the European Society for Photobiology. 2017;16(6):985-995. DOI: 10.1039/c6pp00258g
  2. 2. Holick MF. Vitamin D status: Measurement, interpretation, and clinical application. Annals of Epidemiology. 2009;19(2):73-78. DOI: 10.1016/j.annepidem.2007.12.001
  3. 3. Consiglio M, Viano M, Casarin S, Castagnoli C, Pescarmona G, Silvagno F. Mitochondrial and lipogenic effects of vitamin D on differentiating and proliferating human keratinocytes. Experimental Dermatology. 2015;24(10):748-753. DOI: 10.1111/exd.12761
  4. 4. Yuk JM, Shin DM, Lee HM, Yang CS, Jin HS, Kim KK, et al. Vitamin D3 induces autophagy in human monocytes/macrophages via cathelicidin. Cell Host & Microbe. 2009;6(3):231-243. DOI: 10.1016/j.chom.2009.08.004
  5. 5. Lefebvre d’Hellencourt C, Montero-Menei CN, Bernard R, Couez D. Vitamin D3 inhibits proinflammatory cytokines and nitric oxide production by the EOC13 microglial cell line. Journal of Neuroscience Research. 2003;71(4):575-582. DOI: 10.1002/jnr.10491
  6. 6. Berridge MJ. Vitamin D, reactive oxygen species and calcium signalling in ageing and disease. Philosophical Transactions of the Royal Society of London Series B, Biological Sciences. 2016;371(1700):20150434. DOI: 10.1098/rstb.2015.0434
  7. 7. Gezen-Ak D, Dursun E, Yilmazer S. The effects of vitamin D receptor silencing on the expression of LVSCC-A1C and LVSCC-A1D and the release of NGF in cortical neurons. PLoS One. 2011;6(3):e17553. DOI: 10.1371/journal.pone.0017553
  8. 8. Brewer LD, Porter NM, Kerr DS, Landfield PW, Thibault O. Chronic 1alpha,25-(OH)2 vitamin D3 treatment reduces Ca2+-mediated hippocampal biomarkers of aging. Cell Calcium. 2006;40(3):277-286. DOI: 10.1016/j.ceca.2006.04.001
  9. 9. Hedman AK, Zilmer M, Sundstrom J, Lind L, Ingelsson E. DNA methylation patterns associated with oxidative stress in an ageing population. BMC Medical Genomics. 2016;9(1):72. DOI: 10.1186/s12920-016-0235-0
  10. 10. Pereira F, Barbachano A, Singh PK, Campbell MJ, Munoz A, Larriba MJ. Vitamin D has wide regulatory effects on histone demethylase genes. Cell Cycle. 2012;11(6):1081-1089. DOI: 10.4161/cc.11.6.19508
  11. 11. De Rui M, Toffanello ED, Veronese N, Zambon S, Bolzetta F, Sartori L, et al. Vitamin D deficiency and leisure time activities in the elderly: Are all pastimes the same? PLoS One. 2014;9(4):e94805. DOI: 10.1371/journal.pone.0094805
  12. 12. Berridge MJ. Vitamin D deficiency accelerates ageing and age-related diseases: A novel hypothesis. The Journal of Physiology. 2017;595(22):6825-6836. DOI: 10.1113/JP274887
  13. 13. Balabanova S, Richter HP, Antoniadis G, Homoki J, Kremmer N, Hanle J, et al. 25-Hydroxyvitamin D, 24, 25-dihydroxyvitamin D and 1,25-dihydroxyvitamin D in human cerebrospinal fluid. Klinische Wochenschrift. 1984;62(22):1086-1090. DOI: 10.1007/bf01711378
  14. 14. Eyles DW, Smith S, Kinobe R, Hewison M, McGrath JJ. Distribution of the vitamin D receptor and 1 alpha-hydroxylase in human brain. Journal of Chemical Neuroanatomy. 2005;29(1):21-30. DOI: 10.1016/j.jchemneu.2004.08.006
  15. 15. Annweiler C, Beauchet O. Vitamin d in older adults: The need to specify standard values with respect to cognition. Frontiers in Aging Neuroscience. 2014;6:72. DOI: 10.3389/fnagi.2014.00072
  16. 16. Annweiler C. Vitamin D in dementia prevention. Annals of the New York Academy of Sciences. 2016;1367(1):57-63. DOI: 10.1111/nyas.13058
  17. 17. Eyles D, Brown J, Mackay-Sim A, McGrath J, Feron F. Vitamin D3 and brain development. Neuroscience. 2003;118(3):641-653. DOI: 10.1016/s0306-4522(03)00040-x
  18. 18. Eyles DW, Burne TH, McGrath JJ. Vitamin D, effects on brain development, adult brain function and the links between low levels of vitamin D and neuropsychiatric disease. Frontiers in Neuroendocrinology. 2013;34(1):47-64. DOI: 10.1016/j.yfrne.2012.07.001
  19. 19. Przybelski RJ, Binkley NC. Is vitamin D important for preserving cognition? A positive correlation of serum 25-hydroxyvitamin D concentration with cognitive function. Archives of Biochemistry and Biophysics. 2007;460(2):202-205. DOI: 10.1016/j.abb.2006.12.018
  20. 20. Wilson VK, Houston DK, Kilpatrick L, Lovato J, Yaffe K, Cauley JA, et al. Relationship between 25-hydroxyvitamin D and cognitive function in older adults: The Health, Aging and Body Composition Study. Journal of the American Geriatrics Society. 2014;62(4):636-641. DOI: 10.1111/jgs.12765
  21. 21. Bartali B, Devore E, Grodstein F, Kang JH. Plasma vitamin D levels and cognitive function in aging women: The nurses’ health study. The Journal of Nutrition, Health & Aging. 2014;18(4):400-406. DOI: 10.1007/s12603-013-0409-9
  22. 22. Etgen T, Sander D, Bickel H, Sander K, Forstl H. Vitamin D deficiency, cognitive impairment and dementia: A systematic review and meta-analysis. Dementia and Geriatric Cognitive Disorders. 2012;33(5):297-305. DOI: 10.1159/000339702
  23. 23. van der Schaft J, Koek HL, Dijkstra E, Verhaar HJ, van der Schouw YT, Emmelot-Vonk MH. The association between vitamin D and cognition: A systematic review. Ageing Research Reviews. 2013;12(4):1013-1023. DOI: 10.1016/j.arr.2013.05.004
  24. 24. Annweiler C, Montero-Odasso M, Llewellyn DJ, Richard-Devantoy S, Duque G, Beauchet O. Meta-analysis of memory and executive dysfunctions in relation to vitamin D. Journal of Alzheimer’s Disease: JAD. 2013;37(1):147-171. DOI: 10.3233/JAD-130452
  25. 25. Toffanello ED, Coin A, Perissinotto E, Zambon S, Sarti S, Veronese N, et al. Vitamin D deficiency predicts cognitive decline in older men and women: The Pro.V.A. Study. Neurology. 2014;83(24):2292-2298. DOI: 10.1212/WNL.0000000000001080
  26. 26. Miller JW, Harvey DJ, Beckett LA, Green R, Farias ST, Reed BR, et al. Vitamin D status and rates of cognitive decline in a multiethnic cohort of older adults. JAMA Neurology. 2015;72(11):1295-1303. DOI: 10.1001/jamaneurol.2015.2115
  27. 27. Llewellyn DJ, Lang IA, Langa KM, Melzer D. Vitamin D and cognitive impairment in the elderly U.S. population. The Journals of Gerontology Series A, Biological Sciences and Medical Sciences. 2011;66(1):59-65. DOI: 10.1093/gerona/glq185
  28. 28. Latimer CS, Brewer LD, Searcy JL, Chen KC, Popovic J, Kraner SD, et al. Vitamin D prevents cognitive decline and enhances hippocampal synaptic function in aging rats. Proceedings of the National Academy of Sciences of the United States of America. 2014;111(41):E4359-E4366. DOI: 10.1073/pnas.1404477111
  29. 29. Annweiler C, Schott AM, Rolland Y, Blain H, Herrmann FR, Beauchet O. Dietary intake of vitamin D and cognition in older women: A large population-based study. Neurology. 2010;75(20):1810-1816. DOI: 10.1212/WNL.0b013e3181fd6352
  30. 30. van Schoor NM, Comijs HC, Llewellyn DJ, Lips P. Cross-sectional and longitudinal associations between serum 25-hydroxyvitamin D and cognitive functioning. International Psychogeriatrics. 2016;28(5):759-768. DOI: 10.1017/S1041610215002252
  31. 31. Corless D, Dawson E, Fraser F, Ellis M, Evans SJ, Perry JD, et al. Do vitamin D supplements improve the physical capabilities of elderly hospital patients? Age and Ageing. 1985;14(2):76-84. DOI: 10.1093/ageing/14.2.76
  32. 32. Dhesi JK, Jackson SH, Bearne LM, Moniz C, Hurley MV, Swift CG, et al. Vitamin D supplementation improves neuromuscular function in older people who fall. Age and Ageing. 2004;33(6):589-595. DOI: 10.1093/ageing/afh209
  33. 33. Rossom RC, Espeland MA, Manson JE, Dysken MW, Johnson KC, Lane DS, et al. Calcium and vitamin D supplementation and cognitive impairment in the women’s health initiative. Journal of the American Geriatrics Society. 2012;60(12):2197-2205. DOI: 10.1111/jgs.12032
  34. 34. Dean AJ, Bellgrove MA, Hall T, Phan WM, Eyles DW, Kvaskoff D, et al. Effects of vitamin D supplementation on cognitive and emotional functioning in young adults-a randomised controlled trial. PLoS One. 2011;6(11):e25966. DOI: 10.1371/journal.pone.0025966
  35. 35. Pettersen JA. Does high dose vitamin D supplementation enhance cognition?: A randomized trial in healthy adults. Experimental Gerontology. 2017;90:90-97. DOI: 10.1016/j.exger.2017.01.019
  36. 36. Aspell N, Lawlor B, O’Sullivan M. Is there a role for vitamin D in supporting cognitive function as we age? The Proceedings of the Nutrition Society. 2018;77(2):124-134. DOI: 10.1017/S0029665117004153
  37. 37. Moore K, Hughes CF, Ward M, Hoey L, McNulty H. Diet, nutrition and the ageing brain: Current evidence and new directions. The Proceedings of the Nutrition Society. 2018;77(2):152-163. DOI: 10.1017/S0029665117004177
  38. 38. Grimm MO, Mett J, Hartmann T. The impact of vitamin E and other fat-soluble vitamins on Alzheimer’s disease. International Journal of Molecular Sciences. 2016;17(11):E1785. DOI: 10.3390/ijms17111785
  39. 39. Annweiler C, Llewellyn DJ, Beauchet O. Low serum vitamin D concentrations in Alzheimer’s disease: A systematic review and meta-analysis. Journal of Alzheimer’s Disease: JAD. 2013;33(3):659-674. DOI: 10.3233/JAD-2012-121432
  40. 40. Johansson P, Almqvist EG, Johansson JO, Mattsson N, Andreasson U, Hansson O, et al. Cerebrospinal fluid (CSF) 25-hydroxyvitamin D concentration and CSF acetylcholinesterase activity are reduced in patients with Alzheimer’s disease. PLoS One. 2013;8(11):e81989. DOI: 10.1371/journal.pone.0081989
  41. 41. Shen L, Ji HF. Vitamin D deficiency is associated with increased risk of Alzheimer’s disease and dementia: Evidence from meta-analysis. Nutrition Journal. 2015;14:76. DOI: 10.1186/s12937-015-0063-7
  42. 42. Ulstein I, Bohmer T. Normal vitamin levels and nutritional indices in Alzheimer’s disease patients with mild cognitive impairment or dementia with normal body mass indexes. Journal of Alzheimer’s Disease: JAD. 2017;55(2):717-725. DOI: 10.3233/JAD-160393
  43. 43. Littlejohns TJ, Henley WE, Lang IA, Annweiler C, Beauchet O, Chaves PH, et al. Vitamin D and the risk of dementia and Alzheimer disease. Neurology. 2014;83(10):920-928. DOI: 10.1212/WNL.0000000000000755
  44. 44. Afzal S, Bojesen SE, Nordestgaard BG. Reduced 25-hydroxyvitamin D and risk of Alzheimer’s disease and vascular dementia. Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association. 2014;10(3):296-302. DOI: 10.1016/j.jalz.2013.05.1765
  45. 45. Llewellyn DJ, Lang IA, Langa KM, Muniz-Terrera G, Phillips CL, Cherubini A, et al. Vitamin D and risk of cognitive decline in elderly persons. Archives of Internal Medicine. 2010;170(13):1135-1141. DOI: 10.1001/archinternmed.2010.173
  46. 46. Balion C, Griffith LE, Strifler L, Henderson M, Patterson C, Heckman G, et al. Vitamin D, cognition, and dementia: A systematic review and meta-analysis. Neurology. 2012;79(13):1397-1405. DOI: 10.1212/WNL.0b013e31826c197f
  47. 47. Annweiler C, Rolland Y, Schott AM, Blain H, Vellas B, Herrmann FR, et al. Higher vitamin D dietary intake is associated with lower risk of Alzheimer’s disease: A 7-year follow-up. The journals of Gerontology Series A, Biological Sciences and Medical Sciences. 2012;67(11):1205-1211. DOI: 10.1093/gerona/gls107
  48. 48. Feart C, Helmer C, Merle B, Herrmann FR, Annweiler C, Dartigues JF, et al. Associations of lower vitamin D concentrations with cognitive decline and long-term risk of dementia and Alzheimer’s disease in older adults. Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association. 2017;13(11):1207-1216. DOI: 10.1016/j.jalz.2017.03.003
  49. 49. Ouma S, Suenaga M, Bolukbasi Hatip FF, Hatip-Al-Khatib I, Tsuboi Y, Matsunaga Y. Serum vitamin D in patients with mild cognitive impairment and Alzheimer’s disease. Brain and Behavior. 2018;8(3):e00936. DOI: 10.1002/brb3.936
  50. 50. Wang L, Ying J, Fan P, Weamer EA, DeMichele-Sweet MAA, Lopez OL, et al. Effects of vitamin D use on outcomes of psychotic symptoms in Alzheimer disease patients. The American Journal of Geriatric Psychiatry: Official Journal of the American Association for Geriatric Psychiatry. Sep 2019;27(9):908-917. DOI: 10.1016/j.jagp.2019.03.016
  51. 51. Lehmann DJ, Refsum H, Warden DR, Medway C, Wilcock GK, Smith AD. The vitamin D receptor gene is associated with Alzheimer’s disease. Neuroscience Letters. 2011;504(2):79-82. DOI: 10.1016/j.neulet.2011.08.057
  52. 52. Lee YH, Kim JH, Song GG. Vitamin D receptor polymorphisms and susceptibility to Parkinson’s disease and Alzheimer’s disease: A meta-analysis. Neurological Sciences: Official Journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology. 2014;35(12):1947-1953. DOI: 10.1007/s10072-014-1868-4
  53. 53. Gezen-Ak D, Dursun E, Ertan T, Hanagasi H, Gurvit H, Emre M, et al. Association between vitamin D receptor gene polymorphism and Alzheimer’s disease. The Tohoku Journal of Experimental Medicine. 2007;212(3):275-282
  54. 54. Wang L, Hara K, Van Baaren JM, Price JC, Beecham GW, Gallins PJ, et al. Vitamin D receptor and Alzheimer’s disease: A genetic and functional study. Neurobiology of Aging. 2012;33(8):1844.e1-1844.e9. DOI: 10.1016/j.neurobiolaging.2011.12.038
  55. 55. Mokry LE, Ross S, Morris JA, Manousaki D, Forgetta V, Richards JB. Genetically decreased vitamin D and risk of Alzheimer disease. Neurology. 2016;87(24):2567-2574. DOI: 10.1212/WNL.0000000000003430
  56. 56. Larsson SC, Traylor M, Markus HS, Michaelsson K. Serum parathyroid hormone, 25-hydroxyvitamin D, and risk of Alzheimer’s disease: A Mendelian randomization study. Nutrients. 2018;10(9):E1243. DOI: 10.3390/nu10091243
  57. 57. Olsson E, Byberg L, Karlstrom B, Cederholm T, Melhus H, Sjogren P, et al. Vitamin D is not associated with incident dementia or cognitive impairment: An 18-y follow-up study in community-living old men. The American Journal of Clinical Nutrition. 2017;105(4):936-943. DOI: 10.3945/ajcn.116.141531
  58. 58. SanMartin CD, Henriquez M, Chacon C, Ponce DP, Salech F, Rogers NK, et al. Vitamin D increases Abeta140 plasma levels and protects lymphocytes from oxidative death in mild cognitive impairment patients. Current Alzheimer Research. 2018;15(6):561-569. DOI: 10.2174/1567205015666171227154636
  59. 59. Morello M, Landel V, Lacassagne E, Baranger K, Annweiler C, Feron F, et al. Vitamin D improves neurogenesis and cognition in a mouse model of Alzheimer’s disease. Molecular Neurobiology. 2018;55(8):6463-6479. DOI: 10.1007/s12035-017-0839-1
  60. 60. Cheng J, Rui Y, Qin L, Xu J, Han S, Yuan L, et al. Vitamin D combined with resveratrol prevents cognitive decline in SAMP8 mice. Current Alzheimer Research. 2017;14(8):820-833. DOI: 10.2174/1567205014666170207093455
  61. 61. Jeon SG, Cha MY, Kim JI, Hwang TW, Kim KA, Kim TH, et al. Vitamin D-binding protein-loaded PLGA nanoparticles suppress Alzheimer’s disease-related pathology in 5XFAD mice. Nanomedicine: Nanotechnology, Biology, and Medicine. 2019;17:297-307. DOI: 10.1016/j.nano.2019.02.004
  62. 62. Landel V, Millet P, Baranger K, Loriod B, Feron F. Vitamin D interacts with Esr1 and Igf1 to regulate molecular pathways relevant to Alzheimer’s disease. Molecular Neurodegeneration. 2016;11:22. DOI: 10.1186/s13024-016-0087-2
  63. 63. Grimm MOW, Lauer AA, Grosgen S, Thiel A, Lehmann J, Winkler J, et al. Profiling of Alzheimer’s disease related genes in mild to moderate vitamin D hypovitaminosis. The Journal of Nutritional Biochemistry. 2019;67:123-137. DOI: 10.1016/j.jnutbio.2019.01.015
  64. 64. Dursun E, Gezen-Ak D, Yilmazer S. A novel perspective for Alzheimer’s disease: Vitamin D receptor suppression by amyloid-beta and preventing the amyloid-beta induced alterations by vitamin D in cortical neurons. Journal of Alzheimer’s Disease: JAD. 2011;23(2):207-219. DOI: 10.3233/JAD-2010-101377
  65. 65. Grimm MOW, Thiel A, Lauer AA, Winkler J, Lehmann J, Regner L, et al. Vitamin D and its analogues decrease amyloid-beta (Abeta) formation and increase Abeta-degradation. International Journal of Molecular Sciences. 2017;18(12):E2764. DOI: 10.3390/ijms18122764
  66. 66. Yu J, Gattoni-Celli M, Zhu H, Bhat NR, Sambamurti K, Gattoni-Celli S, et al. Vitamin D3-enriched diet correlates with a decrease of amyloid plaques in the brain of AbetaPP transgenic mice. Journal of Alzheimer’s Disease: JAD. 2011;25(2):295-307. DOI: 10.3233/JAD-2011-101986
  67. 67. Ito S, Ohtsuki S, Nezu Y, Koitabashi Y, Murata S, Terasaki T. 1alpha,25-Dihydroxyvitamin D3 enhances cerebral clearance of human amyloid-beta peptide(1-40) from mouse brain across the blood-brain barrier. Fluids and Barriers of the CNS. 2011;8:20. DOI: 10.1186/2045-8118-8-20
  68. 68. Grimm MO, Lehmann J, Mett J, Zimmer VC, Grosgen S, Stahlmann CP, et al. Impact of vitamin D on amyloid precursor protein processing and amyloid-beta peptide degradation in Alzheimer’s disease. Neuro-degenerative Diseases. 2014;13(2-3):75-81. DOI: 10.1159/000355462
  69. 69. Hooshmand B, Lokk J, Solomon A, Mangialasche F, Miralbell J, Spulber G, et al. Vitamin D in relation to cognitive impairment, cerebrospinal fluid biomarkers, and brain volumes. The Journals of Gerontology Series A, Biological Sciences and Medical Sciences. 2014;69(9):1132-1138. DOI: 10.1093/gerona/glu022
  70. 70. Nourhashemi F, Hooper C, Cantet C, Feart C, Gennero I, Payoux P, et al. Cross-sectional associations of plasma vitamin D with cerebral beta-amyloid in older adults at risk of dementia. Alzheimer’s Research & Therapy. 2018;10(1):43. DOI: 10.1186/s13195-018-0371-1
  71. 71. Neveu I, Naveilhan P, Baudet C, Brachet P, Metsis M. 1,25-dihydroxyvitamin D3 regulates NT-3, NT-4 but not BDNF mRNA in astrocytes. Neuroreport. 1994;6(1):124-126
  72. 72. Brown J, Bianco JI, McGrath JJ, Eyles DW. 1,25-dihydroxyvitamin D3 induces nerve growth factor, promotes neurite outgrowth and inhibits mitosis in embryonic rat hippocampal neurons. Neuroscience Letters. 2003;343(2):139-143. DOI: 10.1016/s0304-3940(03)00303-3
  73. 73. Naveilhan P, Neveu I, Wion D, Brachet P. 1,25-Dihydroxyvitamin D3, an inducer of glial cell line-derived neurotrophic factor. Neuroreport. 1996;7(13):2171-2175
  74. 74. Zhang D, Li M, Dong Y, Zhang X, Liu X, Chen Z, et al. 1alpha,25-Dihydroxyvitamin D3 up-regulates IL-34 expression in SH-SY5Y neural cells. Innate Immunity. 2017;23(7):584-591. DOI: 10.1177/1753425917725391
  75. 75. Kalia LV, Lang AE. Parkinson’s disease. Lancet. 2015;386(9996):896-912. DOI: 10.1016/S0140-6736(14)61393-3
  76. 76. Evatt ML, Delong MR, Khazai N, Rosen A, Triche S, Tangpricha V. Prevalence of vitamin d insufficiency in patients with Parkinson disease and Alzheimer disease. Archives of Neurology. 2008;65(10):1348-1352. DOI: 10.1001/archneur.65.10.1348
  77. 77. Evatt ML, DeLong MR, Kumari M, Auinger P, McDermott MP, Tangpricha V, et al. High prevalence of hypovitaminosis D status in patients with early Parkinson disease. Archives of Neurology. 2011;68(3):314-319. DOI: 10.1001/archneurol.2011.30
  78. 78. Knekt P, Kilkkinen A, Rissanen H, Marniemi J, Saaksjarvi K, Heliovaara M. Serum vitamin D and the risk of Parkinson disease. Archives of Neurology. 2010;67(7):808-811. DOI: 10.1001/archneurol.2010.120
  79. 79. Wang J, Yang D, Yu Y, Shao G, Wang Q. Vitamin D and sunlight exposure in newly-diagnosed Parkinson’s disease. Nutrients. 2016;8(3):142. DOI: 10.3390/nu8030142
  80. 80. Sleeman I, Aspray T, Lawson R, Coleman S, Duncan G, Khoo TK, et al. The role of vitamin D in disease progression in early Parkinson’s disease. Journal of Parkinson’s Disease. 2017;7(4):669-675. DOI: 10.3233/JPD-171122
  81. 81. Peterson AL, Mancini M, Horak FB. The relationship between balance control and vitamin D in Parkinson’s disease-a pilot study. Movement Disorders: Official Journal of the Movement Disorder Society. 2013;28(8):1133-1137. DOI: 10.1002/mds.25405
  82. 82. Arici Duz O, Helvaci YN. Nocturnal blood pressure changes in Parkinson’s disease: Correlation with autonomic dysfunction and vitamin D levels. Acta neurologica Belgica. 7 Mar 2019. DOI: 10.1007/s13760-019-01113-7. Epub ahead of print
  83. 83. Luo X, Ou R, Dutta R, Tian Y, Xiong H, Shang H. Association between serum vitamin D levels and Parkinson’s disease: A systematic review and meta-analysis. Frontiers in Neurology. 2018;9:909. DOI: 10.3389/fneur.2018.00909
  84. 84. Polymeropoulos MH, Lavedan C, Leroy E, Ide SE, Dehejia A, Dutra A, et al. Mutation in the alpha-synuclein gene identified in families with Parkinson’s disease. Science. 1997;276(5321):2045-2047. DOI: 10.1126/science.276.5321.2045
  85. 85. Gatto NM, Paul KC, Sinsheimer JS, Bronstein JM, Bordelon Y, Rausch R, et al. Vitamin D receptor gene polymorphisms and cognitive decline in Parkinson’s disease. Journal of the Neurological Sciences. 2016;370:100-106. DOI: 10.1016/j.jns.2016.09.013
  86. 86. Gezen-Ak D, Alaylioglu M, Genc G, Gunduz A, Candas E, Bilgic B, et al. GC and VDR SNPs and vitamin D levels in Parkinson’s disease: The relevance to clinical features. Neuromolecular Medicine. 2017;19(1):24-40. DOI: 10.1007/s12017-016-8415-9
  87. 87. Suzuki M, Yoshioka M, Hashimoto M, Murakami M, Noya M, Takahashi D, et al. Randomized, double-blind, placebo-controlled trial of vitamin D supplementation in Parkinson disease. The American Journal of Clinical Nutrition. 2013;97(5):1004-1013. DOI: 10.3945/ajcn.112.051664
  88. 88. Hiller AL, Murchison CF, Lobb BM, O’Connor S, O’Connor M, Quinn JF. A randomized, controlled pilot study of the effects of vitamin D supplementation on balance in Parkinson’s disease: Does age matter? PLoS One. 2018;13(9):e0203637. DOI: 10.1371/journal.pone.0203637
  89. 89. Wang JY, Wu JN, Cherng TL, Hoffer BJ, Chen HH, Borlongan CV, et al. Vitamin D(3) attenuates 6-hydroxydopamine-induced neurotoxicity in rats. Brain Research. 2001;904(1):67-75. DOI: 10.1016/s0006-8993(01)02450-7
  90. 90. Sanchez B, Lopez-Martin E, Segura C, Labandeira-Garcia JL, Perez-Fernandez R. 1,25-Dihydroxyvitamin D(3) increases striatal GDNF mRNA and protein expression in adult rats. Brain Research Molecular Brain Research. 2002;108(1-2):143-146
  91. 91. Lin AM, Fan SF, Yang DM, Hsu LL, Yang CH. Zinc-induced apoptosis in substantia nigra of rat brain: Neuroprotection by vitamin D3. Free Radical Biology & Medicine. 2003;34(11):1416-1425
  92. 92. Rcom-H’cheo-Gauthier AN, Meedeniya AC, Pountney DL. Calcipotriol inhibits alpha-synuclein aggregation in SH-SY5Y neuroblastoma cells by a Calbindin-D28k-dependent mechanism. Journal of Neurochemistry. 2017;141(2):263-274. DOI: 10.1111/jnc.13971
  93. 93. Sloka S, Silva C, Pryse-Phillips W, Patten S, Metz L, Yong VW. A quantitative analysis of suspected environmental causes of MS. The Canadian Journal of Neurological Sciences. 2011;38(1):98-105
  94. 94. Koch-Henriksen N, Sorensen PS. The changing demographic pattern of multiple sclerosis epidemiology. The Lancet Neurology. 2010;9(5):520-532. DOI: 10.1016/S1474-4422(10)70064-8
  95. 95. Pierrot-Deseilligny C, Souberbielle JC. Is hypovitaminosis D one of the environmental risk factors for multiple sclerosis? Brain: A Journal of Neurology. 2010;133(Pt 7):1869-1888. DOI: 10.1093/brain/awq147
  96. 96. Lucas RM, Ponsonby AL, Dear K, Valery PC, Pender MP, Taylor BV, et al. Sun exposure and vitamin D are independent risk factors for CNS demyelination. Neurology. 2011;76(6):540-548. DOI: 10.1212/WNL.0b013e31820af93d
  97. 97. Ebers GC. Environmental factors and multiple sclerosis. The Lancet Neurology. 2008;7(3):268-277. DOI: 10.1016/S1474-4422(08)70042-5
  98. 98. Lincoln MR, Montpetit A, Cader MZ, Saarela J, Dyment DA, Tiislar M, et al. A predominant role for the HLA class II region in the association of the MHC region with multiple sclerosis. Nature Genetics. 2005;37(10):1108-1112. DOI: 10.1038/ng1647
  99. 99. Ramagopalan SV, Maugeri NJ, Handunnetthi L, Lincoln MR, Orton SM, Dyment DA, et al. Expression of the multiple sclerosis-associated MHC class II allele HLA-DRB1*1501 is regulated by vitamin D. PLoS Genetics. 2009;5(2):e1000369. DOI: 10.1371/journal.pgen.1000369
  100. 100. Ramagopalan SV, Dyment DA, Cader MZ, Morrison KM, Disanto G, Morahan JM, et al. Rare variants in the CYP27B1 gene are associated with multiple sclerosis. Annals of Neurology. 2011;70(6):881-886. DOI: 10.1002/ana.22678
  101. 101. Ramasamy A, Trabzuni D, Forabosco P, Smith C, Walker R, Dillman A, et al. Genetic evidence for a pathogenic role for the vitamin D3 metabolizing enzyme CYP24A1 in multiple sclerosis. Multiple Sclerosis and Related Disorders. 2014;3(2):211-219. DOI: 10.1016/j.msard.2013.08.009
  102. 102. Baranzini SE, Oksenberg JR. The genetics of multiple sclerosis: From 0 to 200 in 50 years. Trends in Genetics: TIG. 2017;33(12):960-970. DOI: 10.1016/j.tig.2017.09.004
  103. 103. Munger KL, Levin LI, Hollis BW, Howard NS, Ascherio A. Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis. Journal of the American Medical Association. 2006;296(23):2832-2838. DOI: 10.1001/jama.296.23.2832
  104. 104. Smolders J, Menheere P, Kessels A, Damoiseaux J, Hupperts R. Association of vitamin D metabolite levels with relapse rate and disability in multiple sclerosis. Multiple Sclerosis. 2008;14(9):1220-1224. DOI: 10.1177/1352458508094399
  105. 105. Runia TF, Hop WC, de Rijke YB, Buljevac D, Hintzen RQ. Lower serum vitamin D levels are associated with a higher relapse risk in multiple sclerosis. Neurology. 2012;79(3):261-266. DOI: 10.1212/WNL.0b013e31825fdec7
  106. 106. Mowry EM, Krupp LB, Milazzo M, Chabas D, Strober JB, Belman AL, et al. Vitamin D status is associated with relapse rate in pediatric-onset multiple sclerosis. Annals of Neurology. 2010;67(5):618-624. DOI: 10.1002/ana.21972
  107. 107. Simpson S Jr, Taylor B, Blizzard L, Ponsonby AL, Pittas F, Tremlett H, et al. Higher 25-hydroxyvitamin D is associated with lower relapse risk in multiple sclerosis. Annals of Neurology. 2010;68(2):193-203. DOI: 10.1002/ana.22043
  108. 108. Mowry EM, Waubant E, McCulloch CE, Okuda DT, Evangelista AA, Lincoln RR, et al. Vitamin D status predicts new brain magnetic resonance imaging activity in multiple sclerosis. Annals of Neurology. 2012;72(2):234-240. DOI: 10.1002/ana.23591
  109. 109. Mokry LE, Ross S, Ahmad OS, Forgetta V, Smith GD, Goltzman D, et al. Vitamin D and risk of multiple sclerosis: A Mendelian randomization study. PLoS Medicine. 2015;12(8):e1001866. DOI: 10.1371/journal.pmed.1001866
  110. 110. Gianfrancesco MA, Stridh P, Rhead B, Shao X, Xu E, Graves JS, et al. Evidence for a causal relationship between low vitamin D, high BMI, and pediatric-onset MS. Neurology. 2017;88(17):1623-1629. DOI: 10.1212/WNL.0000000000003849
  111. 111. Graves JS, Barcellos LF, Krupp L, Belman A, Shao X, Quach H, et al. Vitamin D genes influence MS relapses in children. Multiple Sclerosis. 2019. DOI: 10.1177/1352458519845842. Epub ahead of print
  112. 112. Smolders J, Damoiseaux J, Menheere P, Hupperts R. Vitamin D as an immune modulator in multiple sclerosis, a review. Journal of Neuroimmunology. 2008;194(1-2):7-17. DOI: 10.1016/j.jneuroim.2007.11.014
  113. 113. Munger KL, Kochert K, Simon KC, Kappos L, Polman CH, Freedman MS, et al. Molecular mechanism underlying the impact of vitamin D on disease activity of MS. Annals of Clinical and Translational Neurology. 2014;1(8):605-617. DOI: 10.1002/acn3.91
  114. 114. Schampel A, Volovitch O, Koeniger T, Scholz CJ, Jorg S, Linker RA, et al. Nimodipine fosters remyelination in a mouse model of multiple sclerosis and induces microglia-specific apoptosis. Proceedings of the National Academy of Sciences of the United States of America. 2017;114(16):E3295-EE304. DOI: 10.1073/pnas.1620052114
  115. 115. Munger KL, Zhang SM, O’Reilly E, Hernan MA, Olek MJ, Willett WC, et al. Vitamin D intake and incidence of multiple sclerosis. Neurology. 2004;62(1):60-65. DOI: 10.1212/01.wnl.0000101723.79681.38
  116. 116. Kimball SM, Ursell MR, O’Connor P, Vieth R. Safety of vitamin D3 in adults with multiple sclerosis. The American Journal of Clinical Nutrition. 2007;86(3):645-651. DOI: 10.1093/ajcn/86.3.645
  117. 117. Smolders J, Peelen E, Thewissen M, Cohen Tervaert JW, Menheere P, Hupperts R, et al. Safety and T cell modulating effects of high dose vitamin D3 supplementation in multiple sclerosis. PLoS One. 2010;5(12):e15235. DOI: 10.1371/journal.pone.0015235
  118. 118. Burton JM, Kimball S, Vieth R, Bar-Or A, Dosch HM, Cheung R, et al. A phase I/II dose-escalation trial of vitamin D3 and calcium in multiple sclerosis. Neurology. 2010;74(23):1852-1859. DOI: 10.1212/WNL.0b013e3181e1cec2
  119. 119. Kampman MT, Steffensen LH, Mellgren SI, Jorgensen L. Effect of vitamin D3 supplementation on relapses, disease progression, and measures of function in persons with multiple sclerosis: Exploratory outcomes from a double-blind randomised controlled trial. Multiple Sclerosis. 2012;18(8):1144-1151. DOI: 10.1177/1352458511434607
  120. 120. Bhargava P, Steele SU, Waubant E, Revirajan NR, Marcus J, Dembele M, et al. Multiple sclerosis patients have a diminished serologic response to vitamin D supplementation compared to healthy controls. Multiple Sclerosis. 2016;22(6):753-760. DOI: 10.1177/1352458515600248
  121. 121. Laursen JH, Sondergaard HB, Sorensen PS, Sellebjerg F, Oturai AB. Vitamin D supplementation reduces relapse rate in relapsing-remitting multiple sclerosis patients treated with natalizumab. Multiple Sclerosis and Related Disorders. 2016;10:169-173. DOI: 10.1016/j.msard.2016.10.005
  122. 122. Darwish H, Haddad R, Osman S, Ghassan S, Yamout B, Tamim H, et al. Effect of vitamin D replacement on cognition in multiple sclerosis patients. Scientific Reports. 2017;7:45926. DOI: 10.1038/srep45926
  123. 123. Rosjo E, Lossius A, Abdelmagid N, Lindstrom JC, Kampman MT, Jorgensen L, et al. Effect of high-dose vitamin D3 supplementation on antibody responses against Epstein-Barr virus in relapsing-remitting multiple sclerosis. Multiple Sclerosis. 2017;23(3):395-402. DOI: 10.1177/1352458516654310
  124. 124. Ricigliano VA, Handel AE, Sandve GK, Annibali V, Ristori G, Mechelli R, et al. EBNA2 binds to genomic intervals associated with multiple sclerosis and overlaps with vitamin D receptor occupancy. PLoS One. 2015;10(4):e0119605. DOI: 10.1371/journal.pone.0119605
  125. 125. Hausler D, Torke S, Peelen E, Bertsch T, Djukic M, Nau R, et al. High dose vitamin D exacerbates central nervous system autoimmunity by raising T-cell excitatory calcium. Brain: A Journal of Neurology. 13 Jul 2019. awz190. DOI: 10.1093/brain/awz190
  126. 126. Geschwind MD. Prion diseases. Continuum. 2015;21(6 Neuroinfectious Disease):1612-1638. DOI: 10.1212/CON.0000000000000251
  127. 127. Asante EA, Smidak M, Grimshaw A, Houghton R, Tomlinson A, Jeelani A, et al. A naturally occurring variant of the human prion protein completely prevents prion disease. Nature. 2015;522(7557):478-481. DOI: 10.1038/nature14510
  128. 128. Suenaga M, Hiramoto Y, Matsunaga Y. Vitamin D 2 interacts with human PrP(c) (90-231) and breaks PrP(c) oligomerization in vitro. Prion. 2013;7(4):312-318. DOI: 10.4161/pri.25739
  129. 129. Brown RH, Al-Chalabi A. Amyotrophic lateral sclerosis. The New England Journal of Medicine. 2017;377(2):162-172. DOI: 10.1056/NEJMra1603471
  130. 130. Wijesekera LC, Leigh PN. Amyotrophic lateral sclerosis. Orphanet Journal of Rare Diseases. 2009;4:3. DOI: 10.1186/1750-1172-4-3
  131. 131. Libonati L, Onesti E, Gori MC, Ceccanti M, Cambieri C, Fabbri A, et al. Vitamin D in amyotrophic lateral sclerosis. Functional Neurology. 2017;32(1):35-40
  132. 132. Blasco H, Madji Hounoum B, Dufour-Rainfray D, Patin F, Maillot F, Beltran S, et al. Vitamin D is not a protective factor in ALS. CNS Neuroscience & Therapeutics. 2015;21(8):651-656. DOI: 10.1111/cns.12423
  133. 133. Yang J, Park JS, Oh KW, Oh SI, Park HM, Kim SH. Vitamin D levels are not predictors of survival in a clinic population of patients with ALS. Journal of the Neurological Sciences. 2016;367:83-88. DOI: 10.1016/j.jns.2016.05.007
  134. 134. Trojsi F, Siciliano M, Passaniti C, Bisecco A, Russo A, Lavorgna L, et al. Vitamin D supplementation has no effects on progression of motor dysfunction in amyotrophic lateral sclerosis (ALS). European Journal of Clinical Nutrition. 13 Jun 2019. DOI: 10.1038/s41430-019-0448-3. Epub ahead of print
  135. 135. Karam C, Barrett MJ, Imperato T, MacGowan DJ, Scelsa S. Vitamin D deficiency and its supplementation in patients with amyotrophic lateral sclerosis. Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia. 2013;20(11):1550-1553. DOI: 10.1016/j.jocn.2013.01.011
  136. 136. Camu W, Tremblier B, Plassot C, Alphandery S, Salsac C, Pageot N, et al. Vitamin D confers protection to motoneurons and is a prognostic factor of amyotrophic lateral sclerosis. Neurobiology of Aging. 2014;35(5):1198-1205. DOI: 10.1016/j.neurobiolaging.2013.11.005
  137. 137. Torok N, Torok R, Klivenyi P, Engelhardt J, Vecsei L. Investigation of vitamin D receptor polymorphisms in amyotrophic lateral sclerosis. Acta Neurologica Scandinavica. 2016;133(4):302-308. DOI: 10.1111/ane.12463
  138. 138. Burne TH, McGrath JJ, Eyles DW, Mackay-Sim A. Behavioural characterization of vitamin D receptor knockout mice. Behavioural Brain Research. 2005;157(2):299-308. DOI: 10.1016/j.bbr.2004.07.008
  139. 139. Gianforcaro A, Hamadeh MJ. Dietary vitamin D3 supplementation at 10x the adequate intake improves functional capacity in the G93A transgenic mouse model of ALS, a pilot study. CNS Neuroscience & Therapeutics. 2012;18(7):547-557. DOI: 10.1111/j.1755-5949.2012.00316.x
  140. 140. Solomon JA, Gianforcaro A, Hamadeh MJ. Vitamin D3 deficiency differentially affects functional and disease outcomes in the G93A mouse model of amyotrophic lateral sclerosis. PLoS One. 2011;6(12):e29354. DOI: 10.1371/journal.pone.0029354
  141. 141. Moreau C, Devos D, Brunaud-Danel V, Defebvre L, Perez T, Destee A, et al. Elevated IL-6 and TNF-alpha levels in patients with ALS: Inflammation or hypoxia? Neurology. 2005;65(12):1958-1960. DOI: 10.1212/01.wnl.0000188907.97339.76
  142. 142. Alexianu ME, Ho BK, Mohamed AH, La Bella V, Smith RG, Appel SH. The role of calcium-binding proteins in selective motoneuron vulnerability in amyotrophic lateral sclerosis. Annals of Neurology. 1994;36(6):846-858. DOI: 10.1002/ana.410360608
  143. 143. Gianforcaro A, Hamadeh MJ. Vitamin D as a potential therapy in amyotrophic lateral sclerosis. CNS Neuroscience & Therapeutics. 2014;20(2):101-111. DOI: 10.1111/cns.12204
  144. 144. Long K, Nguyen LT. Roles of vitamin D in amyotrophic lateral sclerosis: Possible genetic and cellular signaling mechanisms. Molecular Brain. 2013;6:16. DOI: 10.1186/1756-6606-6-16
  145. 145. A novel gene containing a trinucleotide repeat that is expanded and unstable on Huntington’s disease chromosomes. The Huntington’s Disease Collaborative Research Group. Cell. 1993;72(6):971-983. DOI: 10.1016/0092-8674(93)90585-e
  146. 146. Telenius H, Kremer B, Goldberg YP, Theilmann J, Andrew SE, Zeisler J, et al. Somatic and gonadal mosaicism of the Huntington disease gene CAG repeat in brain and sperm. Nature Genetics. 1994;6(4):409-414. DOI: 10.1038/ng0494-409
  147. 147. McColgan P, Tabrizi SJ. Huntington’s disease: A clinical review. European Journal of Neurology. 2018;25(1):24-34. DOI: 10.1111/ene.13413
  148. 148. Chel VG, Ooms ME, van der Bent J, Veldkamp F, Roos RA, Achterberg WP, et al. High prevalence of vitamin D deficiency and insufficiency in patients with manifest Huntington disease: An explorative study. Dermato-endocrinology. 2013;5(3):348-351. DOI: 10.4161/derm.26135
  149. 149. Molnar MF, Torok R, Szalardy L, Sumegi E, Vecsei L, Klivenyi P. High-dose 1,25-dihydroxyvitamin D supplementation elongates the lifespan of Huntington’s disease transgenic mice. Acta Neurobiologiae Experimentalis. 2016;76(3):176-181
  150. 150. Seuter S, Neme A, Carlberg C. Epigenome-wide effects of vitamin D and their impact on the transcriptome of human monocytes involve CTCF. Nucleic Acids Research. 2016;44(9):4090-4104. DOI: 10.1093/nar/gkv1519
  151. 151. Grant WB, Soles CM. Epidemiologic evidence supporting the role of maternal vitamin D deficiency as a risk factor for the development of infantile autism. Dermato-endocrinology. 2009;1(4):223-228. DOI: 10.4161/derm.1.4.9500
  152. 152. Dealberto MJ. Prevalence of autism according to maternal immigrant status and ethnic origin. Acta Psychiatrica Scandinavica. 2011;123(5):339-348. DOI: 10.1111/j.1600-0447.2010.01662.x
  153. 153. Mostafa GA, Al-Ayadhi LY. Reduced serum concentrations of 25-hydroxy vitamin D in children with autism: Relation to autoimmunity. Journal of Neuroinflammation. 2012;9:201. DOI: 10.1186/1742-2094-9-201
  154. 154. Chen J, Xin K, Wei J, Zhang K, Xiao H. Lower maternal serum 25(OH) D in first trimester associated with higher autism risk in Chinese offspring. Journal of Psychosomatic Research. 2016;89:98-101. DOI: 10.1016/j.jpsychores.2016.08.013
  155. 155. Vinkhuyzen AAE, Eyles DW, Burne THJ, Blanken LME, Kruithof CJ, Verhulst F, et al. Gestational vitamin D deficiency and autism-related traits: The generation R study. Molecular Psychiatry. 2018;23(2):240-246. DOI: 10.1038/mp.2016.213
  156. 156. Coskun S, Simsek S, Camkurt MA, Cim A, Celik SB. Association of polymorphisms in the vitamin D receptor gene and serum 25-hydroxyvitamin D levels in children with autism spectrum disorder. Gene. 2016;588(2):109-114. DOI: 10.1016/j.gene.2016.05.004
  157. 157. Schmidt RJ, Hansen RL, Hartiala J, Allayee H, Sconberg JL, Schmidt LC, et al. Selected vitamin D metabolic gene variants and risk for autism spectrum disorder in the CHARGE study. Early Human Development. 2015;91(8):483-489. DOI: 10.1016/j.earlhumdev.2015.05.008
  158. 158. Cannell JJ. Vitamin D and autism, what’s new? Reviews in Endocrine & Metabolic Disorders. 2017;18(2):183-193. DOI: 10.1007/s11154-017-9409-0
  159. 159. Ghanizadeh A, Akhondzadeh S, Hormozi M, Makarem A, Abotorabi-Zarchi M, Firoozabadi A. Glutathione-related factors and oxidative stress in autism, a review. Current Medicinal Chemistry. 2012;19(23):4000-4005
  160. 160. Ali A, Vasileva S, Langguth M, Alexander S, Cui X, Whitehouse A, et al. Developmental vitamin D deficiency produces behavioral phenotypes of relevance to autism in an animal model. Nutrients. 2019;11(5):E1187. DOI: 10.3390/nu11051187
  161. 161. Alfawaz HA, Bhat RS, Al-Ayadhi L, El-Ansary AK. Protective and restorative potency of vitamin D on persistent biochemical autistic features induced in propionic acid-intoxicated rat pups. BMC Complementary and Alternative Medicine. 2014;14:416. DOI: 10.1186/1472-6882-14-416
  162. 162. Saad K, Abdel-Rahman AA, Elserogy YM, Al-Atram AA, El-Houfey AA, Othman HA, et al. Randomized controlled trial of vitamin D supplementation in children with autism spectrum disorder. Journal of Child Psychology and Psychiatry, and Allied Disciplines. 2018;59(1):20-29. DOI: 10.1111/jcpp.12652
  163. 163. Casseb GAS, Kaster MP, Rodrigues ALS. Potential role of vitamin D for the management of depression and anxiety. CNS Drugs. 2019;33(7):619-637. DOI: 10.1007/s40263-019-00640-4
  164. 164. Parker GB, Brotchie H, Graham RK. Vitamin D and depression. Journal of Affective Disorders. 2017;208:56-61. DOI: 10.1016/j.jad.2016.08.082
  165. 165. Okereke OI, Singh A. The role of vitamin D in the prevention of late-life depression. Journal of Affective Disorders. 2016;198:1-14. DOI: 10.1016/j.jad.2016.03.022
  166. 166. Li H, Sun D, Wang A, Pan H, Feng W, Ng CH, et al. Serum 25-hydroxyvitamin d levels and depression in older adults: A dose-response meta-analysis of prospective cohort studies. The American Journal of Geriatric Psychiatry: Official Journal of the American Association for Geriatric Psychiatry. 5 Jun 2019. S1064-7481(19)30393-8. DOI: 10.1016/j.jagp.2019.05.022
  167. 167. Mohaddesi H, Saei Ghare Naz M, Najarzadeh M, Yeganehpour M, Khalkhali H. Correlation between depression with serum levels of vitamin D, calcium and magnesium in women of reproductive age. Journal of Caring Sciences. 2019;8(2):117-119. DOI: 10.15171/jcs.2019.017
  168. 168. de Koning EJ, Lips P, Penninx BW, Elders PJ, Heijboer AC, den Heijer M, et al. Vitamin D supplementation for the prevention of depression and poor physical function in older persons: The D-Vitaal study, a randomized clinical trial. The American Journal of Clinical Nutrition. 24 Jul 2019. nqz141. DOI: 10.1093/ajcn/nqz141
  169. 169. Libuda L, Laabs BH, Ludwig C, Buhlmeier J, Antel J, Hinney A, et al. Vitamin D and the risk of depression: A causal relationship? Findings from a Mendelian randomization study. Nutrients. 2019;11(5):E1085. DOI: 10.3390/nu11051085
  170. 170. Valipour G, Saneei P, Esmaillzadeh A. Serum vitamin D levels in relation to schizophrenia: A systematic review and meta-analysis of observational studies. The Journal of Clinical Endocrinology and Metabolism. 2014;99(10):3863-3872. DOI: 10.1210/jc.2014-1887
  171. 171. Torrey EF, Miller J, Rawlings R, Yolken RH. Seasonality of births in schizophrenia and bipolar disorder: A review of the literature. Schizophrenia Research. 1997;28(1):1-38
  172. 172. Saha S, Chant DC, Welham JL, McGrath JJ. The incidence and prevalence of schizophrenia varies with latitude. Acta Psychiatrica Scandinavica. 2006;114(1):36-39. DOI: 10.1111/j.1600-0447.2005.00742.x
  173. 173. Eyles DW, Trzaskowski M, Vinkhuyzen AAE, Mattheisen M, Meier S, Gooch H, et al. The association between neonatal vitamin D status and risk of schizophrenia. Scientific Reports. 2018;8(1):17692. DOI: 10.1038/s41598-018-35418-z
  174. 174. Krivoy A, Onn R, Vilner Y, Hochman E, Weizman S, Paz A, et al. Vitamin D supplementation in chronic schizophrenia patients treated with clozapine: A randomized, double-blind. Placebo-controlled Clinical Trial. EBioMedicine. 2017;26:138-145. DOI: 10.1016/j.ebiom.2017.11.027
  175. 175. Ghaderi A, Banafshe HR, Mirhosseini N, Moradi M, Karimi MA, Mehrzad F, et al. Clinical and metabolic response to vitamin D plus probiotic in schizophrenia patients. BMC Psychiatry. 2019;19(1):77. DOI: 10.1186/s12888-019-2059-x
  176. 176. Naudin J, Capo C, Giusano B, Mege JL, Azorin JM. A differential role for interleukin-6 and tumor necrosis factor-alpha in schizophrenia? Schizophrenia Research. 1997;26(2-3):227-233
  177. 177. Asadzadeh Manjili F, Kalantar SM, Arsang-Jang S, Ghafouri-Fard S, Taheri M, Sayad A. Upregulation of vitamin D-related genes in schizophrenic patients. Neuropsychiatric Disease and Treatment. 2018;14:2583-2591. DOI: 10.2147/NDT.S176301

Written By

Anna A. Lauer, Daniel Janitschke, Tobias Hartmann, Heike S. Grimm and Marcus O.W. Grimm

Submitted: 05 August 2019 Reviewed: 13 August 2019 Published: 30 October 2019