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 (β=45; SE=0.16; P=0.008) and negative psychotic experiences (β=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 (β=71; SE=0.29; P=0.016) and negative psychotic experiences (β=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.