Date Published: January 20, 2017
Publisher: Public Library of Science
Author(s): S. Kilian, J. K. Burns, S. Seedat, L. Asmal, B. Chiliza, S. Du Plessis, M. R. Olivier, M. Kidd, R. Emsley, Brion Maher.
Childhood trauma is a recognised risk factor for schizophrenia. It has been proposed that childhood trauma interferes with normal neurodevelopment, thereby establishing a biological vulnerability to schizophrenia. Poor premorbid adjustment is frequently a precursor to schizophrenia, and may be a manifestation of neurodevelopmental compromise. We investigated the relationship between childhood trauma and premorbid adjustment in 77 patients with first-episode schizophrenia spectrum disorders. We also investigated possible mediating roles for other selected risk factors in the relationship. We found several significant correlations between different trauma types and both social and academic premorbid adjustment from childhood to late adolescence. There were no significant moderating effects for family history of schizophrenia or family history of psychiatric disorder. History of obstetric complications, substance abuse and poor motor coordination weakened some of the associations between childhood trauma and premorbid adjustment, while poor sequencing of motor acts strengthened the association. Our results confirm previous studies indicating an association between childhood trauma and premorbid adjustment. Results indicate a general rather than specific association, apparent with different types of trauma, and affecting both social and academic components of premorbid adjustment across childhood, early and late adolescence. Further, our results suggest a complex interplay of various risk factors, supporting the notion of different pathways to psychosis.
Schizophrenia is widely regarded as a neurodevelopmental disorder, with genetic and environmental risk factors interacting to contribute to altered brain development and later manifestation of the illness . Premorbid adjustment (i.e. an individual’s functioning across social and academic domains from childhood through to early adulthood prior to the onset of psychosis) has long been a focus of interest in schizophrenia research . Deficits in premorbid adjustment are reported consistently as a precursor to schizophrenia , and as such provide supportive evidence for the neurodevelopmental model [4–5]. For example, poor social adjustment during childhood has been proposed as an early manifestation of impairment of developmental trajectories that evolve into deficits in social cognition and later into schizophrenia .
In contrast to several previous studies [26,15, 17, 27–28] we did not find higher rates of childhood trauma in patients compared with matched controls. However, this may be explained by the fact that the rates of childhood trauma documented in both patients and controls in this study were generally higher than those reported in other studies. For example, in our sample 29.3% patients and 26.9% controls endorsed high levels of sexual abuse and 39.2% patients and 28.8% controls endorsed high levels physical abuse. In comparison, in a UK-based study, 16% of first episode psychosis patients and 13% controls reported severe sexual abuse and 24% patients and 13% controls reported severe physical abuse . In a study conducted in Switzerland, 12% patients reported sexual abuse and 17.7% reported physical abuse . Our findings are consistent with those of a meta-analysis that compared rates of childhood trauma across countries and found that that Lower and Middle Income Countries (LMIC) had higher rates than upper income countries . Notably, LMICs have higher rates of crime, poverty and unemployment—all of which are socio-economic factors known to influence childhood trauma rates [30–31]. Alternatively, the high rates of reported childhood trauma in our sample may relate to measurement with the CTQ. Although the CTQ is extensively used it is a subjective self-report instrument and unlike clinician-rated instruments more likely to lead to over-reporting. Our finding that physical neglect was the most commonly cited childhood trauma type in both patients and controls is consistent with other studies [15, 32]. Tikka  found this to be the case in both ‘at clinical high risk patients’ and controls, while Wang  found this for patients with both first-episode and chronic schizophrenia. However, another study found that emotional and not physical neglect was most frequently reported in patients with first-episode psychosis .
In conclusion, our results confirm previous studies indicating an association between childhood trauma and premorbid adjustment, and suggest that this association is apparent for different types of trauma, and for both social and academic components of premorbid adjustment across childhood, early and late adolescence. Further, our results suggest a complex interplay of various risk factors, supporting the notion of different pathways to psychosis. Our results suggesting that childhood trauma might act largely independently of pre-existing genetic liability, obstetric complications and substance abuse count against a simple cumulative model of the shared effect of adversities on the risk of psychosis. It may be that individuals with psychosis have different adversity profiles . Further studies exploring the ways in which putative risk factors for neurodevelopmental compromise and the evolution of psychosis interact with one another are warranted.