Childhood trauma and psychotic disorders: a systematic, critical review of the evidence.

There is controversy over whether childhood trauma (CT) is a causal factor in the development of psychosis. This review aims to identify and critically analyze the association between CT and psychotic disorders. Studies investigating CT and psychotic disorder were identified by searches of electronic databases and manual searches of references lists, and 46 studies were identified. Forty studies had no control group, only psychiatric control groups, or unmatched, nonpopulation control groups and thus had methodologies that were inadequate to determine the relationship between CT and psychosis. Six studies used appropriate control groups. Three studies found an association between CT and psychosis, 2 found potentially real associations that failed to reach statistical significance, and 1 found no association, tentatively suggesting a relationship between CT and psychotic disorders. Several methodological problems were found in the studies in the review, including the highest quality studies, which limit the strength of the conclusions that can be drawn from them. These were lack of statistical power, lack of attention to moderating or mediating variables, the way in which CT was measured, and the use of cross-sectional research designs. These problems, some of which may be unavoidable in CT research, suggest the need for new and innovative methodologies in the investigation of CT and psychosis. Directions for further research are explored.