In this paper we tackle the difficulties present in adequately conceptualising child abuse and neglect, we provide data on its incidence and we describe the main psychopathological consequences associated with each type of child maltreatment.
Thus, we focus on the heterogeneity of the phenomenon (heterogeneity of the notion of "child maltreatment", heterogeneity of the classification criteria, heterogeneity of the different approaches that are related to maltreatment and the heterogeneity of the causes and consequences) and on the complexity that gives rise to that heterogeneity to define the child abuse and neglect.
In children and adolescents, child abuse and neglect can produce a decline in their biological, psychological and social functions. Child maltreatment in childhood and adolescence is recognised as an important psychopathological risk factor and is associated with poor psychological function in childhood and adolescence and adulthood. In this respect, we emphasise that it is wrong to believe that current knowledge has enabled the identification of clearly differentiated consequences for each type of child maltreatment. There is a high degree of co-morbidity among the different types, in such a way that many children experience more than one form of maltreatment and display common consequences. Moreover, it still needs to be clarified whether child abuse and neglect produces a general vulnerability towards psychopathology, in such a way that other factors would be responsible for the form finally adopted by psychopathology.
2. Definition of child abuse
Historically, the definition of child abuse has passed through different stages. At first, it was the academics and professionals attending the cases of child maltreatment who tried to define child abuse and neglect by focusing on the characteristics of the maltreated children . At the beginning of the 1990’s, there was still a lack of consensus from the scientific community on a common definition of child abuse and neglect . Despite vigorous debates on this matter, little has been achieved to provide a clear, reliable, valid and useful definition of child abuse and neglect .
Problems in proposing effective operational definitions include factors such as the lack of social consensus on unacceptable or dangerous parenting styles or actions; the lack of certainty on the appropriateness of defining child abuse and neglect according to the adults’ behaviour, to its effect on the children, or to a combination of both; the controversy over whether damage criteria should be included in the definition of maltreatment, and the confusion over whether similar definitions should be used for scientific, legal and clinical purposes .
Based on ideas set out by Aber and Zigler , Cicchetti and Barnett  and Zuravin , Palacios, Moreno and Jiménez  consider that main difficulty in defining child abuse lies in the heterogeneity of the phenomenon. They consider the following dimensions: heterogeneity of the notion of "child maltreatment", heterogeneity of the classification criteria, heterogeneity of the different approaches related to the maltreatment and heterogeneity of the causes and consequences. In our review of the conceptualisation of child abuse and neglect we will follow the proposal made by these authors.
2.1. Heterogeneity of the notion of "child maltreatment"
The generic label of maltreatment includes a significant variety of types (physical abuse, child neglect, sexual abuse, etc.) and subtypes (e.g. physical abuse would have subtypes like burns, blows with injuries, drowning, etc.) on which no unanimity exists between researchers [14,7].
Various authors [15-17] postulate that child abuse and neglect can be conceptualised as a continuum. Thus, in its most restricted form, we would encounter definitions of child abuse and neglect that only include intentional and severe physical abuse and, in its broadest form, we would have the definitions that include everything that could interfere in the child’s optimum development [18,19].
Initially, the concept of child maltreatment was restricted to the “severe physical harm generally caused by one of the parents or caregivers” . This definition excluded other forms of maltreatment such as sexual abuse, cases of child neglect and emotional maltreatment, except when they led to physical injuries. This early research led to an increase in the scientific community’s interest in child abuse and neglect as a focus of study and concern. In a short time, the definition of abuse was extended to include emotional deprivation, malnutrition, child neglect and sexual abuse, and the consequences derived from physical and emotional abandonment were evaluated. This extension of the definition of child abuse and neglect contributed to consolidating the idea that not all abusive parents wanted to destroy their descendents and considered the social factors as determining factors in explaining the etiology of child maltreatment [3,21].
Based on research and studies carried out in the 1980’s, broader conceptualisation of child abuse and neglect has progressively been constructed [1,22, 23], defining it as all actions carried out by the caregivers, which significantly interfere in the child’s optimum development and do not adhere to social standards. This conceptualisation contemplates aspects such as neglecting the physical-biological, cognitive, emotional and social needs, and the different types of child maltreatment are also classified.
The heterogeneity of the phenomenon is not only related to the conceptualisation of the different types of child maltreatment, but also to the areas in which it takes place. Thus, we speak of child abuse and neglect in the family context, in the social context or in development contexts outside of the family microsystem and in the institutional area, as is the case of the context of schools or residential care centres, etc. .
2.2. Heterogeneity of the identification criteria
Important discrepancies exist between the criteria on which the identification of child abuse and neglect should be based. According to Palacios, Moreno and Jiménez , "the presence of child maltreatment can be decided by considering the intentions or consequences; it may require evidence or be based on suspicions; it may or may not establish strict frequency of occurrence criteria, distinguishing between isolated episodes and recurrent behaviour; it may or may not be set against dominant social perceptions, which tend to establish borders between discipline and physical abuse, for example”. The use of one criteria or another would lead to essential modifications in the statistics, the conclusions on the etiology, the prevention models and the intervention guidelines in cases of child maltreatment .
An adequate approach to the definition of child abuse and neglect should take into consideration the concept of intentionality . Kempe, Silverman, Steele, Droegemueller, & Silver  recognise the importance of this aspect in their definition of abuse (“… any child who receives non-accidental physical harm as a result of actions or omissions by their parents or caregivers”). Another significant aspect of the criteria to be considered when defining child abuse is the aspect regarding the consequences that the child maltreatment would have on the child. According to De Paúl , we would have to consider three basic issues when defining child abuse:
The developmental perspective: the child’s age may be the difference between an abusive action or omission or normal behaviour. It is not the same to leave a 3-month-old baby alone for a few hours as it is a 10-year-old child. Thus, both the limit of what can be considered maltreatment and its severity can depend on the child’s developmental moment.
The child’s vulnerability: The same parental behaviour may not be harmful for a healthy child; however, it may be abusive or negligent if the child has a serious chronic illness or some type of disability.
The consequences for the child: When assessing the consequences of the maltreatment we must take into account that, on a high percentage of occasions, the harm or injuries do not appear on the child immediately and, except in exceptional circumstances, the psychological consequences are more serious than the physical ones. On the other hand, we must assess the potential harm that the child could eventually suffer if this parental behaviour is continued for a certain amount of time at the same level of severity.
The frequency of abusive behaviour and the chronicity of such conduct are important factors when considering behaviour to be abusive or not, as well as their severity . Moreover, as it is a phenomenon that is defined in the community, an adequate definition of child abuse and neglect must implicitly recognise the importance of community and cultural standards [26-27]. It is impossible to discriminate between abusive and non-abusive parents, if you do not take into account the standard community values or the social representation of the abuse. For this purpose, it is necessary to consider that cultures are substantially different from each other in the guidelines for bringing up children, the degree in which childhood is recognised as a stage of development that deserves special attention, the conditions considered necessary for healthy development and the rights recognised to children .
2.3. Heterogeneity of professional approaches related to the abuse phenomenon
Five approaches or perspectives are distinguished, which have had a notable influence on the definition of child abuse and neglect: The medical approach, the legal approach, the sociological approach, the research perspective, the subjective approach and the ecological perspective. Table 1 combines the determining factors and the essential objective of each of these approaches.
The medical perspective defines maltreatment as the action that causes physical harm to the child . It focuses on the diagnosis, and therefore, a cardinal aspect of this perspective is the notion that child abuse and neglect is the symptom of a medical pathology and pursues the objective of establishing a system to classify potentially abusive parents. The medical approach asks the question: Is this parent potentially abusive?
The definition of the medical approach on child abuse and neglect is closed and essentially limited to the most severe cases of abuse, documented with x-rays that provide proof of injuries such as multiple fractures and subdural haematomas. From this perspective, the treatment of the disorder from which the abusive parents are believed to suffer takes on great importance. According to Barnett, Manly, & Cicchetti , by grouping child abuse with other children’s illnesses, the medical community releases society from any responsibility in the etiology of the abuse and provides an optimistic view of the problem which is conceived as a phenomenon that can be resolved through research and treatment focused on the abusive parents.
In the sociological perspective, which emerged partly as a reaction and criticism to the pathological model of child abuse and neglect, the actions of abuse are defined by the cultural standards of a specific society [1,30]. The sociological definition focuses on the very fact of the abuse and not on the characteristics of the abusers. The sociological approach asks the question: How serious is this type of maltreatment? What is needed to control it? [30,21,5].
The theorists of the sociological perspective stress the importance of counting on public opinion and the professionals’ opinion when defining what unacceptable parental behaviour should be and they emphasise the importance of knowing society’s role in the perpetuation of child maltreatment. Furthermore, the sociological perspective proclaims a more open definition of child abuse and neglect which includes a wide range of parental actions that have negative consequences on the child, such as child neglect in all its forms.
In the legal approach the definitions focus on demonstrating the harm, not necessarily physical, that has been caused to the child. The definition of what maltreatment is or is not is based on the State’s initiative to create a legal child protection system. From this perspective, hardly any doubts and contradictions arise when it is a case of demonstrating physical abuse, as the evidence is usually tangible and conclusive. However, psychological maltreatment, for example, was questioned by the legal system until very recently, due to the difficulties in proving its occurrence.
From the research approach or ecological perspective numerous efforts have been made to define child maltreatment, its nature, causes and effects, programmes for intervention, control and prevention of the problem, etc. In this way, numerous definitions, etiological models and contradictions have arisen. We must point out that with the objective of discovering the characteristics of abusive parents, the actions of abuse, the consequences in the children and the environmental conditions in which the maltreatment is produced, the research approach has aimed to open up the concept of child abuse and neglect by focusing on the ecology of human development [33-35], in the studies of family/environment transaction and in the role of the community support systems.
Lastly, from the subjective approach, maltreatment is defined by oneself. That is to say, the subjective experience of abuse is defined by the victim through their own perception, language and considerations. From this perspective, the main aim of the child protection system is to discover the subjective experience of maltreatment in the victim and promote the necessary therapeutic actions for their treatment .
Taking into account the number of approaches that exist, it is not surprising that different professionals access the problem of maltreatment along different routes, either by using their own classification criteria and/or their own detection procedures and placing more emphasis on some aspects rather than others [1,4,36]. In this way, the researchers, social workers, health workers, educators and the Child Protection Services frequently have different and often contradictory views about the diverse aspects regarding abuse, which substantially respond to their own objectives. Thus, the child abuse and neglect can be considered as a medical problem, which needs to be diagnosed and treated; as criminal conduct that needs to be defined in legal terms and punished; as a social problem that needs to be analysed as a social phenomenon; as a problem of child protection, which requires the resources and intervention of the Child Protection Services; and as a family problem, which needs to be understood in the context of the family dynamics [37-38].
Zuravin  suggests that, insofar as research is concerned, the studies that focus on specific acts that harm the child may be the most appropriate. The challenge of researchers is to develop a precise operational definition that minimises the lack of agreement among professionals. This lack of consensus on what constitutes maltreatment greatly obstructs the communication and collaboration between the respective fields of intervention.
According to Zigler and Hall , the absence of a consensus on the definition of child abuse and neglect could be explained, at least in part, by the lack of agreement to accept that one single definition is not capable of meeting all the aspects that the social scientists and the social services professionals consider relevant in order to conceptualise the maltreatment. Aber and Zigler  propose the development of three different categories of definitions: legal definitions, definitions for the management of cases and definitions for research. In any case, the way in which child maltreatment is defined can affect factors such as the classification of the cases and their severity, decision-making regarding the legal and social actions that must be undertaken (by whom, how and at what time) and even the perception of who is maltreating, who is maltreated, either by themselves or by others . According to Giovannoni and Becerra , the lack of definition can lead to the situation of some children and adolescents who require protection not being detected, whilst other children or adolescents, who have not been maltreated, are inadequately classified and subjected to unnecessary treatment and intervention.
2.4. Heterogeneity of the causes and the consequences
Early research developed to clarify the etiology of child abuse focused on the abusive parents. Thus, numerous authors have suggested that child abuse and neglect is produced as a result of the actions of perverse parents with mental health problems [39-41]. Other authors have emphasised the importance of the stressful interactive role between the environment, the abuser and the abused child [30,42-44]. Several authors have focused on the children’s characteristics (age, physical health, behaviour, etc.) as factors that can provoke the maltreatment from caregivers . Multi-factor models have also been developed, such as the Integrative-Ecological Model , the Transactional Model  and the Ecological-Transactional Model  which represented a considerable advance in knowledge on the etiology of child abuse and neglect.
As regards the consequences of child abuse and neglect, it is not surprising that, depending on the perspective adopted for its definition, the professional approach and the explicative model on the causes of the maltreatment, the results found are also diverging.
Based on this context, the following definition of child abuse and negelct is proposed:
Definition of Child Abuse and Neglect: Any physical and/or psychological harm, which parents or caregivers inflict on children who are in their care or custody or for whom they are responsible, as the result of physical, sexual or emotional actions, of omission or commission, which interfere or threaten the adequate development of the child and violate the community demands concerning the good treatment of children.
2.5. Some myths and false beliefs about child abuse and neglect
One of the most important aspects in the detection and prevention of maltreatment is the social representation that the members of a particular society have regarding this problem. The social representation of child abuse and neglect has also experienced an evolution in which ideas, beliefs and distortions have gradually been ruled out which would explain seminal aspects of child abuse and neglect. We will now take a look at them:
Child abuse is infrequent. A recent study by the World Health Organisation  points out that millions of children suffer some form of abuse and require medical and social attention. It should be noted that around 53,000 children are murdered every year; the prevalence of sexual abuse is 73 million (7%) and 150 million (14%) in boys and girls, respectively, under 18 years of age; and between 25% and 50% of the children inform that they have been physically abused. The strong belief that the family is a place where people can find affection and support makes it harder to believe that a high number of people are involved in family violence .
Child maltreatment is a consequence of psychological traits and psychopathological problems of the parents. Various research studies focusing on abusive parents, in comparison with non-abusive parents, have found a greater presence of symptoms like depression, anxiety, low levels of personal self-esteem [47-49], lack of skills to adequately handle situations of stress , antisocial behaviour , personality disorders , dissociative symptoms  schizophrenia  impulsive tendencies [53,40] and difficulties controlling reactions of tension . However, there is a low frequency of psychiatric diagnoses among the perpetrators of child maltreatment. At present, the authors accept that in 10% to 15% of the cases of maltreatment the parents show some kind of mental disorder [50,55].
Child abuse and neglect is limited to the lowest social classes. It is a mistaken belief to think that child maltreatment is only a question of educational or economic deficiencies. The data shows that child abuse and neglect exists in all countries and, although it is not distributed proportionally, it occurs in all social classes [56,41].
Child abuse and neglect is understood as an extension and generalisation of the physical abuse. At present, different forms of child maltreatment have been recognised (emotional maltreatment, child neglect, etc.) which go beyond physical abuse. An adequate understanding of the different forms of maltreatment is necessary in order to encourage good detection and prevention of ill-treatment.
Child abuse and neglect is transmitted from parents to children and so on. The notion of intergenerational transmission of child abuse and neglect upholds that all children who are maltreated will maltreat their children in the future or, on the contrary, all parents who maltreat their children were maltreated in their childhood. The current accepted rate of intergenerational transmission of child abuse and neglect among researchers is around 25% (+/- 5) of the cases. Most of the people who were maltreated as a child (around 70%) do not reproduce this problem with their children .
3. Incidence of the problem
Children in a situation of vulnerability constitute a social problem that affects all societies of the world. Throughout history, violence against children has been practiced in many ways: physically and emotionally, through sexual and labour exploitation. Therefore, child maltreatment is not a new phenomenon; it has been around since the beginning of time. History documents that the problem of child abuse and neglect is present from the start of civilisation and that, despite this, abusive conducts have for a long time gone “unnoticed” for families and for communities [58-60].
From the social discovery of the abuse phenomenon, different governments and societies have aimed to carry out research to discover the real scope of the problem.
The most contrasted data on this matter comes from the United States and Great Britain. For instance, according to the governmental statistics published in the United States [12,61], it is estimated that 1.8 million U.S. children may be the victims of child maltreatment every year, of which around 800,000 are cases that are actually confirmed. This data was collected from the Child Protection Services, to which we should add the cases that are not detected by these sources and/or are not reported.
In the United States, the rate of victimisation for every 1000 children is 12.4, whereby it is children under three who display the highest rates of victimisation; that is to say, 16 children are maltreated per 1000 . In Great Britain, the rate of child abuse and neglect, in children under 18 years of age is 2.8 children per 1000, whereby the highest percentages are found in children under one (7.1 per 1000) .
Besides the negative consequences it has on the victim, child abuse and neglect also has important consequences for society. The price paid for child maltreatment is very high; it has a direct cost (e.g. hospitalisations, social and judicial action, victim support programmes, child protection measures, etc.) and an indirect cost (pain, decrease in the quality of life, a less healthy and positive society, etc.). For instance, it is estimated that in the United States, child maltreatment annually generates costs to the value of 56 billion dollars .
4. Psychopathological consequences of the child abuse and neglect
Child maltreatment can produce a decline in biological, psychological and social function in children and adolescents. Maltreatment in childhood and adolescence is recognised as an important psychopathological risk factor and is associated with poor psychological function in childhood [64-71] and in adolescence [68,72-75] and in adulthood [76-78].
As we have already mentioned, many different difficulties exist to adequately classify the phenomenon of child abuse and neglect. In this respect, it would be wrong to think that current knowledge has allowed us to identify clearly differentiated consequences for each type of child maltreatment. There is a high degree of co-morbidity between the different types, to the extent that many children experience more than one form of maltreatment and demonstrate common consequences [79-80]. Furthermore, it still needs to be clarified whether child maltreatment produces psychopathology in children or whether it generates general vulnerability towards psychopathology in such a way that other factors would be responsible for the type of psychopathological deviation eventually adopted.
Despite these limitations, many studies have found an association between different types of child maltreatment and various psychopathological symptoms in adolescence and at the beginning of adulthood. We will now briefly focus on the psychopathological consequences associated with each type of maltreatment.
4.1. Psychopathological consequences of physical abuse
Being physically abused in childhood is a risk factor associated with psychopathological problems in adolescence and adulthood. Numerous research studies have demonstrated that physically abused adolescents and adults who were subjected to physical abuse in childhood have a high risk of displaying mental health problems [81-88].
By way of example, various studies have found that children and young people who are the victims of physical abuse and children and young people who are part of a violent family context, in comparison with children and young people who do not display these characteristics, display more emotional problems [69,84,89-91]. The research reveals that physical abuse is associated with a variety of emotional problems such as somatisation, depression, anxiety, hostility, paranoid ideation, psychosis, posttraumatic symptoms and dissociative disorder. This relationship is moderated by aspects such as the presence of multiple types of abuse and the gender of the perpetrator. The data obtained in the various research studies indicates that the combination of physical and sexual abuse has greater emotional consequences for the victims, generating above all, depression and anxiety [92-94].
An important association exists between being physically abused in childhood and an increase in the manifestation of self-harming behaviour and suicides in adolescence and adulthood [94-101]. However, different research studies have demonstrated that this correlation varies depending on the victim’s gender, the type of abuse and the level of parental conflict. For instance, it has been suggested that physical abuse in itself does not produce suicidal behaviour; however, when physical and sexual abuse are experienced together, this behaviour seems to be produced more frequently .
Much of the literature on child abuse and neglect has related physical abuse with delinquency and aggressive behaviour in adolescence. A close relationship has also been found between physical abuse and conduct disorder which, in turn, has been associated with delinquency and aggressive behaviour .
4.2. Psychopathological consequences of child neglect
Having suffered child neglect in childhood has been associated with poor psychological function in childhood, adolescence and adulthood.
The results of studies such as the Minnesota Mother-Child Project  verify that children who were victims of physical neglect displayed serious social-emotional problems, and most of these problems had an internalising nature. In the same way, in other studies, it has been found that physical neglect and a lack of supervision in childhood is associated with an increase in the risk of producing self-harming behaviour and suicidal tendencies [72,101], suffering from personality disorders with high symptoms of anxiety, depression  and dissociative disorders in adolescence and adulthood .
4.3. Psychopathological consequences of sexual abuse
Research on sexual abuse suggests that children and adolescents who develop in an abusive environment run the risk of suffering psychological difficulties that are characterised by emotional dysregulation. In particular, it has be found that children who are the victims of sexual abuse show internalising and externalising difficulties, posttraumatic stress disorder symptoms, personality disorders and problems in interpersonal relations with peers [61,106-110].
One of the most worrying aspects for the physical and mental health of the abused adolescent in their childhood is the strong association that exists between sexual abuse and suicidal conduct in this evolutionary stage . The percentage of attempted suicides in the adolescent population of victims of sexual abuse ranges between 7.3 and 11.2% in girls and 3.2 and 4.5% in boys [99,112].
By way of example, in one of the most relevant research projects carried out recently in this field by Martin et al. , in which 2,485 adolescents participated, of which 7.4% had been the victim of sexual abuse, they discovered that 27.1% of the sample admitted having suicidal ideation (21.8% of boys and 33.6% of girls); 13.7% had planned to commit suicide (11.3% of boys and 16.4% of girls) and 4.5% of boys and 7.3% of girls had attempted suicide.
4.4. Psychopathological consequences of emotional maltreatment
At present, sufficient evidence is available to confirm that emotional maltreatment in childhood is associated with mental health problems and adaptation problems in adolescence and adulthood [95,113-116].
Emotional maltreatment has been identified as a strong predictor of most psychological problems including personality disorders, anxiety, depression, dissociative symptoms, posttraumatic stress, physical symptoms, suicidal behaviour, sexual dysfunction, eating disorders and low self-esteem [32,74-75,95,114-123].