A cognitive intermediate phenotype study confirming possible gene–early adversity interaction in psychosis outcome: A general population twin study

Aims: To investigate the interaction between childhood adversity and genetic risk in the formation of psychotic symptoms, using cognitive speed as indicator of genetic risk. Methods: In a cross?twin, cross?trait analysis of monozygotic twins in the general population, the association between childhood adversity and psychotic symptoms was examined, using a cognitive intermediary phenotype as genetic risk marker. Results: Psychotic symptoms in the proband twin were associated with childhood adversity and, independently, with a measure of cognitive speed in the co?twin. The association between childhood adversity and psychotic symptoms was much stronger (interaction: ?2=8.48, p=0.004) if cognitive speed was worse. Conclusion: Higher level of genetic risk associated with psychosis may moderate the impact of childhood adversity on the risk of adult psychotic symptom formation.