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Can sexual abuse during childhood lead to the later development of psychotic illnesses?
There has been increasing awareness of the prevalence of childhood sexual abuse (CSA) and the psychological damage that this can cause. In recent years there have been many cases of alleged abuse within institutions that have led to litigation for compensation. One issue that has arisen in these cases and is of significance in clinical practice is whether CSA is a causative factor in the later development of schizophrenia or psychotic illnesses presenting with delusions and hallucinations.
In a recent case in Birmingham, UK,1 involving a man in his thirties who was abused by a Catholic priest, the causation of schizophrenia was claimed to be the CSA that he had suffered. The judge stated: “The likelihood as it seems to be is the terrible abuse to which ‘A' was subjected led to his both suffering post traumatic stress disorder and that disorder of the mind which is symptomatic of schizophrenia”. Based on the expert evidence of psychiatrists presented in court, the judge accepted that the claimant was suffering from schizophrenia; he also clarified that “what is important is that his adult psychiatric problems, however they are classified, were caused by his childhood sexual abuse difficulties” and awarded a large sum of money to the CSA victim who developed symptoms of schizophrenia in adulthood.
Due to variations in the definition of abuse, studies in the last three decades have found the prevalence rates of CSA vary widely from 2.9–27% among women and 0–16% among men.2 These rates are also complicated by possible under reporting of cases because of stigma, guilt, embarrassment, suppression of painful memories and the private nature of the issue.
There have been large numbers of studies looking at rates of CSA in various psychiatric conditions. The majority of these have been retrospective studies of either the general population or they addressed rates of CSA among people with particular psychiatric conditions. There is also a difficulty interpreting studies due to the definition of CSA, ranging from non‐genital contact to serious and sustained penetrative sexual intercourse and wide variations in the duration of abuse. Several studies have supported the strong relationship between CSA and adult psychopathology among both women and men,2,3,4 and concluded that the longer and more serious in nature of the abuse, the greater the psychological impact on victims. In essence, sexual abuse that continues for a longer period of time and involves penetration, intrafamilial abuse, greater age gap and aggression4,5,6 is more like to cause psychopathology and psychiatric illnesses.
The general finding is that there are increased rates of CSA in almost all psychiatric conditions: childhood mental disorders, mood disorders, eating disorders, personality disorders, drug and alcohol abuse, dissociative disorders and posttraumatic conditions.2,3,5,6,7,8,9,10,11 There are also studies that found an association with schizophrenia and psychotic illnesses, but the findings are not consistent.4,7,8,9,12,13
There is also evidence that among people diagnosed with schizophrenia or psychotic illnesses there is a higher rate of CSA reported.4,7,8 A recent international literature review of studies that involved CSA and psychotic illnesses or schizophrenia7 found that there were very few articles in this area. The authors concluded that CSA increases the risk of developing psychotic illnesses and raises the importance of “asking about childhood trauma when trying to understand or assist people diagnosed with psychosis or schizophrenia”, and also highlighted the training needs of clinical staff. In summation of this review the authors concluded that CSA is a causal factor for psychotic illness and schizophrenia, in particular for hallucinations.7
An Australian prospective study,9 involving 1612 CSA cases, showed a mild increase in rates of schizophrenic disorder, but the authors concluded that the strength of association was not enough to support a causal link between CSA and psychotic illness. They identified their limitations and described this as a “systematic bias against establishing higher rates of disorder in victims of CSA is introduced by the 5% of the general population controls likely to have been themselves victims of penetrative CSA”. They also acknowledged that “the average age of subjects in their study was in the 20's and many have yet to pass the peak years for developing schizophrenia and related disorders”. They do not exclude an association but stated that care must be taken in linking CSA as a causal factor in the development of schizophrenia.9
Another more recent study of 8580 adults in the UK13 concluded that problems with victimisation contribute to the vulnerability to psychotic illness. A prospective study of 4045 adults from the Netherlands4 suggested that in the general population people who have been abused were more likely to go on to develop a psychotic illness.
A New Zealand study3 found that events subsequent to the CSA are critical in determining the long‐term impact on mental health and self‐esteem and they can become the mediating factors that could minimise the adverse outcome. This study highlighted the needs of psychological support or treatment for the victims of abuse to ameliorate the serious damaging effects that abuse has inflicted on them.
In other large population studies of psychological morbidity and CSA there has often been no mention of psychotic illnesses, or there is no difference in lifetime prevalence of schizophrenia and related disorders, when comparing abused groups to non‐abused groups.5,10
If one is considering whether CSA causes schizophrenia on the basis of the stress diathesis model for the development of schizophrenia, the question is whether CSA acts as a general stressor for all psychiatric conditions, or is CSA a causative factor for schizophrenia in which there may be a more genetic or hard‐wired factor in its development? Rutter and Maughan14 state that there is good evidence that there are statistical connections between adverse childhood experiences and adult psychopathology and, furthermore, there is evidence that at least part of the risk is environmentally mediated. He emphasises the interactive nature of the various developmental processes and the difficulty in identifying a single risk factor as causative.
One of the major methodological difficulties in looking for causation is that there tends to be clustering of risk factors. The population of people who suffer CSA are more likely to have suffered other aspects of abuse, together with being at higher risk due to family histories of mental illness and social deprivation. Similarly children who have sexual abuse recognised in childhood may be placed in care, which in itself may be an additional risk factor. Victims of CSA are also more likely to abuse alcohol or drugs, all of which put them at higher risk of developing psychotic illnesses in later years. Without a long‐term prospective study of large numbers of children who were sexually abused, it is very difficult to be certain whether CSA is an additional risk factor in schizophrenia in these children compared with children from similar backgrounds who were not sexually abused.
With currently available literature there is no definitive evidence to support the proposal that CSA is a major risk or causal factor for the later development of schizophrenia or psychotic illnesses, as study findings are inconsistent and there is an absence of studies with the power and design to prove such a link. There is discussion as to whether it may alter the presentation of schizophrenia or psychotic illness in terms of content, prognosis or treatment. There is some evidence that people who were sexually abused are more likely to have certain types of hallucinations (command hallucinations) and thoughts related to sexual abuse.7,8,12 The degree to which post‐traumatic symptoms are part of the presentation, and flavour the symptomatology, may also be important.
The adverse effects of CSA can be long lasting. CSA victims are therefore more likely to be vulnerable to particular kinds of stress in all possible ways, which can precipitate the relapse of any psychiatric illnesses including psychotic illnesses or schizophrenia. The psychological effects of guilt, hopelessness and helplessness may also influence the prognosis of any severe mental illness. Therefore, in people with schizophrenia the traumatic experience of sexual abuse may have an impact on prognosis and care should be taken in addressing these complex and sophisticated needs. There is also the risk of relapse of psychotic symptoms when considering psychological intervention to manage the history of abuse. This can lead to difficult decisions about the extent to which these should be addressed when providing individual psychological support to a patient with a psychotic illness.
Patients with histories of severe abuse and borderline personality disorder presenting bizarrely with transient delusional symptoms may be difficult to classify in regard to whether or not they are suffering from psychotic illness or schizophrenia, and this may overlap with post‐traumatic stress disorder or dissociative disorder. In individual cases, the disclosure of sexual abuse by the patient or as part of a police enquiry may trigger a brief psychotic episode; also, patients suffering from schizophrenia may relapse following such revelations and this may cause diagnostic uncertainty.
The recognition of CSA in child care institutions has led to large numbers of people from vulnerable groups who have been in care claiming compensation for abuse. One would predict within these groups the prevalence of schizophrenia would be above the expected rate in the general population due to well‐recognised risk factors for schizophrenia. The difficulty in a legal case is to determine—on the balance of probabilities—whether a person would not otherwise have developed schizophrenia if not for the abuse. This is particularly the case when patients may have been taken into care where they were abused or neglected due to family disturbances or social deprivation, or when associated with a family history of psychiatric disorder and substance abuse.
The current level of research does not allow us to be confident in reaching the conclusion that CSA is a causal factor in schizophrenia, but neither does it allow us to rule out the possibility that it might be. However, CSA is a common factor in people with schizophrenia and clinicians should note the significance of serious childhood trauma while not necessarily assuming it is the cause of the patient's illness.
Declaration of interest: None