Abstract

Background

Stressful life events (SLEs) are associated with psychotic experiences. SLEs might act as an environmental risk factor, but may also share a genetic propensity with psychotic experiences.

Aims

To estimate the extent to which genetic and environmental factors influence the relationship between SLEs and psychotic experiences.

Method

Self- and parent reports from a community-based twin sample (4830 16-year-old pairs) were analysed using structural equation model fitting.

Results

SLEs correlated with positive psychotic experiences (r = 0.12–0.14, all P<0.001). Modest heritability was shown for psychotic experiences (25–57%) and dependent SLEs (32%). Genetic influences explained the majority of the modest covariation between dependent SLEs and paranoia and cognitive disorganisation (bivariate heritabilities 74–86%). The relationship between SLEs and hallucinations and grandiosity was explained by both genetic and common environmental effects.

Conclusions

Further to dependent SLEs being an environmental risk factor, individuals may have an underlying genetic propensity increasing their risk of dependent SLEs and positive psychotic experiences.