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.