Social isolation. A Swedish conscript study examined the interaction of premorbid personality and social isolation. Young men who felt they were more sensitive than their peers, had fewer than two close friends, and did not have a girlfriend had an increased risk of later developing schizophrenia. Again this raises the question of whether social isolation is an expression of a schizoid or schizotypal personality or whether it is an independent risk factor. Perhaps both may be true: individuals with a schizoid/schizotypal personality may be less able to form social relationships, and then the social isolation itself may lead to increasing deviance.
A study found that single people had a slightly higher risk of developing psychosis if they lived in a neighborhood with few other singles, suggesting that single status might produce perceived/actual social isolation if most others live with a partner. Whether social isolation increases the risk for schizophrenia (or whether a close relationship may be protective) has also been raised, where marriage was shown to have a protective effect for males – and not simply a consequence of better-adjusted males being able to marry.
Stressful life events Some prospective studies have found an association between life events and onset of psychosis. Stressful life events in the 3 weeks preceding onset or relapse seemed important (although the effect size was greater in affective psychosis than in schizophrenia). But some events may have been precipitated by inherited personality characteristics.