The term alopecia comes from the Greek
Hair is one of the characteristic features of mammals. Hair is an essential speciality for protecting humans from environmental factors, producing sebum and pheromones and apocrine sweat. It affects someone's role in sexual and social relationships. Hair acts a major role for thermoregulation and it is a resource for stem cells .
Hair is a derivate of the epidermis. Hair has two different parts: one of them is the hair shaft and the other is the follicle. The generation of hair depends on the follicle. Cortex, cuticle cells and a medulla for some types of hairs are the parts of the hair shaft. Hair follicle is an essential part for hair growth and it grows continuously. The continuous growth and rest sequence is named hair cycle. The span of hair growth depends on many endocrine, neural stimuli and vascular stimuli. Various factors such as age, localization of the hair and nutritional habits have an impact on the nature of hair.
Nearly there are 5 million hair follicles in humans, and scalp has 100,000 of them. Mainly terminal hairs are on scalp, eyelashes and eyebrows, whereas vellus hairs cover the rest of the body . Hair is formed in two different parts: follicle is located under the skin and it is the living part and the other one is the hair shaft, above the skin surface, and it is fully keratinized non‐living part. Hair development is a continuous cyclic process. Hair growth cycle consists of growth (anagen), regression (catagen), rest (telogen) and shedding (exogen); mature follicles go through all of these process. The location of the hair, hormonal balance, personal nutrition and age can affect the duration of the phases [3, 4].
Especially feminine appearance, attractiveness, personal image and sexuality can be affected according to the healthy hair. Hair is an important point for a healthy look, social image and communication. All individuals complain about hair loss without thinking about age and gender but hair loss can have more dramatical effects on females than on males, because hair loss can change the life quality and social communication. That is why dermatological clinics take much interest in hair loss problems.
Hair loss can be due to a wide variety of causes such as scarring and non‐scarring diseases.
Physicians think that the treatment of alopecia can be so challenging. Variable treatments with different effects can be applied to the patients. These treatments consist of systemic, intralesional or topical corticosteroids, systemic or local phototherapy, cyclosporine‐A, acupuncture, interferon‐α, anthralin, topical immunotherapy agents, topical minoxidil and photodynamic therapy [9–11]. Although the stem cells of hair follicles spread into the scalp typically in order to re‐grow hair, there are no useful and existing treatments to recover alopecia areata. It is a chronic disease and the consequences can be disruptive for psychological and physical appearance. The impressiveness of treatments decreases due to the spontaneous relapses and remissions and these courses can be unpredictable. This application has been shown as allergic contact dermatitis; topical sensitizers have a major role to begin a delayed‐type (type IV) hypersensitivity reaction by acting as haptens. To make a complete antigen, these sensitizers help to bind to an endogenous protein. There are some applications to aim topical sensitization such as dinitrochlorobenzene, SADBE and DPCP .
The quality of life is also affected by AA; in most studies, AA is the sort of alopecia, and psychological and social factors have an impact on this disease. The incidence of lifetime major depressive symptoms and anxiety disorders in AA patients was estimated as 39% in one study . Besides, antisocial personality disorder and post‐traumatic stress disorder were observed at a high rate in those patients. In AA patients, antisocial personality and post‐traumatic disorders were found at a high rate.
It is essential to examine the whole scalp and skin biopsies for finding the main reason for cicatricial alopecia are necessary. There are three main groups for primary cicatricial alopecia: lymphocytic, neutrophilic and mixed. It is classified according to the types of inflammatory cells examined histologically where hair follicles are affected. It could be so difficult to differentiate the primary cicatricial alopecia types because of the various forms of this disease and it ends with complete hair loss. The most visible symptom of this disease is the active inflammation. In this condition, the most substantial aim for treatment is to stop or slow down the development of this disease. For the patients with lymphocytic primary cicatricial alopecia, topical and intralesional corticosteroids and antimalarials can be applied and in persistent conditions, systemic immunosuppressive agents can be tried. The applications of antibiotics and retinoids are the most essential medications to treat neutrophilic cicatricial alopecia.
This disease can be seen as acute and chronic and it is classified according to its duration. If the duration of disease is shorter than 6 months, it is known as acute telogen effluvium; if the hair loss is longer than 6 months, it is accepted as chronic telogen effluvium. The hair loss can be apparent 2 or 3 months later in acute telogen effluvium disease. The aetiologic factors or events of telogen effluvium may not be detected in 33% of the patients. Some tests can be applied to patients such as the hair‐pull test and the result of this test is positive. In addition to that, inflammation is not found in telogen effluvium. In the trichogram test, the telogen hair ratio reaches above 25% in telogen effluvium. A fine evaluation is to be done to understand the real cause and the most substantial factors: to treat telogen effluvium is to find the natural process of telogen effluvium. If the triggering factor of this disease can be found and stopped, hair loss will generally decrease within 3–6 months [15, 16].
The symptoms of trichotillomania resemble the obsessive‐compulsive spectrum, so this disease is mainly included among psychiatric diseases . Trichotillomania usually begins in early ages and become chronic with gradual events. It can also be seen in adolescence at the beginning of 12 years. The adults can also face this disease at old ages. Trichotillomania can be confused with AA in older patients in the first phase of the disease because it appeared mostly in females [18, 19]. When we observe more than a third of paediatric patients with trichotillomania, there have been many psychiatric disorders such as attention deficit‐hyperactivity disorder, anxiety disorder, obsessive‐compulsive disorder and depression. But unfortunately, the studies show that 40% of the trichotillomania patients could not be diagnosed and 58% patients never received correct medications .
It has been understood that there have been many reasons for hair loss. Dermatologists always apply different methods for finding the main evidence of the disease. The dermatologist also will carefully look at patient's scalp and hair. For instance, they have to pull their patients’ hair to get the true results, and it is named as ‘pull test’. Pulling hair test can be helpful to describe the process of hair loss. And dermatologists should sometimes observe the whole body to understand the ratio of hair loss. To make sure about the evidence, they also use blood tests. By using blood tests, they can find other reasons for hair loss such as iron deficiency, anaemia, thyroid disease or vitamin deficiencies. The dermatologists can also apply punch biopsy to detect histopathological reasons. All of the applications should be done to find out some clues in your scalp .
Although medical treatment is a useful method for patients and physicians, the results of treatment could be unsuccessful. Instead of other techniques, hair transplantation should be used for androgenetic alopecia. Hair transplantation method is essential not only for androgenetic alopecia but also good for other kinds of hair loss. The other kinds of problems include cicatricial alopecias, congenital alopecias, post‐burn sequelae and alopecia areata . Lately, hair transplantation has been common for treating hair loss. ‘Follicular unit transplantation’ and ‘Follicular unit extraction’ are the main types of this method. In follicular unit transplantation, occipital region is the main area for taking skin patches; they can be separated manually to grafts and put to the recipient area. ‘Follicular unit extraction’ is the other method in order to treat hair loss. In this method, 1‐mm diameter micrografts are taken from the donor area and they are transferred to predrilled holes. This technique is less painful and more comfortable for patients because it does not cause a linear scar. The essential disadvantage of this treatment is that patients should spend much more time for extracting grafts. Due to the ‘punched–out’ sites, donor transferring into the area can be limited [24, 25].
3. Psychosocial effects
Alopecia occurs not only for physical reasons but also because of psychological problems. They have a major role in this serious condition. It has a significant psychological impact on the quality of life.
The incidence of alopecia always increases because of the psychological problems. Patients with alopecia are exposed to mental disorders such as post‐traumatic stress disorder, social phobia, depression, anxiety and suicidal thoughts. Psychological/psychiatric disorders have been detected at rates up to 60% in dermatology patients treated as inpatients .
Mental disorders are observed to be a higher risk among women with scarring alopecia. Hair loss can be an important reason for psychological/psychiatric problems such as embarrassment, depression, anxiety about their appearance, low self‐esteem, anger, less social and sexual activity and even suicidal thoughts. Because of the connection between alopecia and mental disorders, dermatologists and psychologists/psychiatrists have to find the main reasons for the hair loss together [27, 28].
The aim of this chapter is to review the latest developments in the understanding of hair loss and its treatment. The contents cover the molecular and cell biological aspects of hair follicles through to the pathogenesis of alopecia, its treatment with topical and systemic agents, and new treatment options such as hair transplantation, mesotherapy and platelet‐rich plasmas (PRPs).