This critical note aside, in recent years, there has been a small number of large population-based studies that provide data more relevant to this question,5,18–21
and these are summarized in .
Summary of Recent Population-Based Studies of Childhood Trauma and Psychosis
Using data on 8580 subjects aged 16–74 from the British National Survey of Psychiatric Morbidity, Bebbington et al18
found that those who met criteria for a definite or probable psychotic disorder (n
= 60) were over 15 times more likely to have been sexually abused at some point in their lifetime (not restricted to childhood). When the interrelationship between other negative life events and level of depression were controlled, the odds ratio was markedly reduced, though still significant (Adj. OR 2.9). However, the measure of sexual abuse was crude (a single question), no account was taken of timing, duration, or severity of abuse, and childhood and adult exposure were not distinguished.
In their analysis of data on 4045 subjects aged 18–64 drawn from the Netherlands Mental Health Survey and Incidence Study, Janssen et al19
found that those who had experienced emotional, physical, or sexual abuse or neglect before the age of 16 were more likely to report experiencing psychotic symptoms during a 3-year follow-up period. The effect was strongest for the most severe psychosis groups and held after adjusting for a range of potential confounding variables (eg, need for care level psychosis: Adj. OR 7.3). However, the number of subjects with psychotic symptoms was very small, particularly those with the most severe symptoms (n
= 7), meaning the confidence intervals for each odds ratio were very wide, and while there was evidence that the risk of developing psychosis increased in a dose-response fashion with increasing severity of abuse, no formal test for trend across levels of abuse severity was reported. In a more recent study using a similar design, Spauwen et al,21
using data on 2524 subjects aged 14–24 from the Early Developmental Stages of Psychopathology study, found that the experience of any lifetime trauma (from a list of 9 events, not restricted to childhood) was associated with the development of 3 or more (but not fewer) psychotic symptoms during an average follow-up period of 42 months (Adj. OR 1.9). The trauma exerting the strongest independent effect was natural catastrophe (Adj. OR 15.1) followed by physical threat (Adj. OR 2.1). The risk of developing 3 or more psychotic symptoms was elevated in those who reported sexual abuse (Adj. OR 1.6) but not significantly and by much less than in the studies by Bebbington et al18
and Janssen et al.19
However, as in the study by Bebbington et al,18
the measure of trauma was relatively crude, again with no account taken of timing, duration, or severity.
In the only study in which the occurrence of sexual abuse was determined using contemporaneous records, Spataro et al5
compared rates of subsequent hospital admissions in those who had been sexually abused before the age of 16 (n
= 1612), according to official records, with admission rates in a large population-based control sample (n
= 3 139 745). They found no association between child sexual abuse and later admission to hospital with a diagnosis of schizophrenia (relative risk 1.2). However, as the majority of cases of sexual abuse go unrecognized, meaning many cases of sexual abuse will have been included in the control sample, the potential for this study to detect a difference was limited. Further, by definition, the cases of abuse included were the subject of some form of state intervention, and this may have had protective effects on later risk of psychopathology.
In another recent large population-based study (n
= 17 337), Whitfield et al20
found that respondents reporting a history of hallucinations were more likely to have been both physically (Adj. OR 1.7) and sexually (Adj. OR 1.7) abused during childhood. The sample size is a strength, but the study is cross-sectional and the measure of hallucinations extremely limited (ie, a single question, see ). Nonetheless, this is in line with findings from a number of previous (much smaller) studies, which have reported higher rates of hallucinations in patients with a psychotic illness (or in clinical populations more generally) who had experienced various forms of trauma in childhood compared with those who had not.22–24
The evidence regarding delusions is more equivocal. Janssen et al,19
for example, reported higher rates of both hallucinations and delusional ideation in those who had experienced childhood abuse, but others have found no association between early trauma and delusions.16
Only a small number of studies have investigated other symptoms, such as negative symptoms,25,26
and no clear patterns emerge.
The findings from the recent, more robust, studies of childhood trauma are suggestive of a link with adult psychosis. However, the findings have not been altogether consistent and a number of complicating conceptual and methodological issues remain.