Childhood adversity and psychosis: Examining whether the association is due to genetic confounding using a monozygotic twin differences approach

Purpose: To test whether the association between childhood adversity and positive and negative psychotic experiences is due to genetic confounding. Method: Childhood adversity and psychotic experiences were assessed in an ongoing sample of 226 twins from the general population. A monozygotic (MZ) twin differences approach was used to assess possible genetic confounding. Results: In the whole sample, childhood adversity was significantly associated with positive (beta =45; SE = 0.16; P = 0.008) and negative psychotic experiences (beta = 0.77; SE = 0.18; P < 0.01). Within-pair MZ twin differences in exposure to childhood adversity were significantly associated with differences in positive (beta = 71; SE = 0.29; P= 0.016) and negative psychotic experiences (beta = 98; SE = 0.38; P= 0.014) in a subsample of 85 MZ twin pairs. Conclusions: Individuals exposed to childhood adversity are more likely to report psychotic experiences. Furthermore, our findings indicate that this association is not due to genetic confounding. (C) 2012 Elsevier Masson SAS. All rights reserved.