Negative symptoms and their predictors in schizophrenia within the Northern Finland 1966 Birth Cohort

Negative symptoms are a major scientific and therapeutic challenge in schizophrenia. We report the occurrence and predicting factors of negative symptoms at two time points in a population-based birth cohort. The negative symptoms of subjects with Diagnostic and Statistical Manual of Mental Disorders, third edition, revised (DSM-III-R) schizophrenia (n = 46) were scrutinized at the first hospitalization due to psychosis from hospital records (first-episode psychosis) and with an interview approximately 10 years later (follow-up phase). Developmental and sociodemographic predictors of negative symptoms in first-episode psychosis, follow-up phase and at both measurements were analysed. Forty-one percent of the subjects had negative symptoms at the first episode, 39% in the follow-up phase, and in 24% the symptoms persisted at both measurements. Smoking at the age of 14, definite psychosocial stressor and not being married predicted more negative symptoms whereas good school performance and using less alcohol at age 14 predicted fewer persistent negative symptoms. These findings are new. However, we were not able to identify any major premorbid phenotype or endophenotype predicting negative symptoms which support the view that negative symptoms might mainly be a specific part of the illness.