Psychological mediators of the association between childhood adversities and psychosis: A systematic review

This is the first review to identify, summarise and critically evaluate studies that examined psychological mediators of the relationship between childhood adversities and psychosis. A database search (PsychINFO, MEDLINE, Web of Science, CINAHL) was conducted to identify eligible studies published between January 1980 and September 2017. A narrative synthesis and appraisal of methodological quality and statistical appropriateness of the primary studies was conducted. We identified 37 papers, comprising 9057participants with psychotic disorders and 63,059 non-clinical participants. Despite great variation in the mediators considered and the methodological and analytic quality of the primary studies, our synthesis suggests that the relationship between childhood adversity and psychosis is mediated by several "families" of mediating variables including post-traumatic sequelae (e.g. dissociation, PTSD symptoms), affective dysfunction and dysregulation, and maladaptive cognitive factors (e.g. self-esteem and beliefs and concepts about the self and others). More tentative evidence was observed for the role played by appraisals of subsequent circumstantial factors (e.g. "life hassles"). Substance misuse was not found to be a prominent mediator of the relationship between childhood adversity and psychotic experiences, but further high quality corroborative studies are required. The importance of the five different (but not independent or mutually exclusive) families of mediators considered by the present evidence synthesis should be examined by future research employing appropriate modelling methods to better disentangle the contribution of these different processes. Nonetheless, they represent potentially valuable intervention targets that clinicians should consider whilst developing treatment plans for trauma survivors with distressing psychotic symptoms.