The influence of risk factors on the onset and outcome of psychosis: What we learned from the GAP study

The GAP multidisciplinary study carried out in South London, recruited 410 first episode of psychosis patients and 370 controls; the aim was to elucidate the multiple genetic and environmental factors influencing the onset and outcome of psychosis. The study demonstrated the risk increasing effect of adversity in childhood (especially parental loss, abuse, and bullying) on onset of psychosis especially positive symptoms. Adverse life events more proximal to onset, being from an ethnic minority, and cannabis use also played important roles; indeed, one quarter of new cases of psychosis could be attributed to use of high potency cannabis. The “jumping to conclusions” bias appeared to mediate …