Premorbid adjustment and personality in people with schizophrenia†

BACKGROUND: Schizoid personality and poor social adjustment have been thought of as common antecedents of schizophrenia but the existing literature is inconclusive. We have carried out a large cohort study with improved methodology. METHOD: The premorbid personality and adjustment of 50,054 Swedish men were assessed on entry into the army at the age of 18. Individuals who developed schizophrenia or another psychosis after 15-year follow-up were identified. Odds ratios for variables independently associated with the later development of schizophrenia were calculated, adjusting for potential confounders. RESULTS: Four variables reflecting early problems with interpersonal relationships were strongly associated with later schizophrenia and, to a lesser extent, non-schizophrenic psychoses, but also occurred commonly in the cohort as a whole. These associations with schizophrenia persisted after early-onset cases were excluded, though their predictive value was low (3.0%, 95% CI 1.5-4.5). CONCLUSIONS: Some aspects of premorbid personality and adjustment may act as risk factors for schizophrenia. The results appear to be most consistent with a multi-factorial aetiology for schizophrenia and offer tentative support for a psychological disturbance mediating genetic and environmental effects on the causal pathway to the illness.