Age at onset in a cohort of schizophrenics in Nigeria.

Over a period of 3 years, 340 patients (199 men and 141 women) who met DSM-III-R criteria for schizophrenia and who knew their exact date of birth were interviewed to determine the age at onset of illness. The immediate family's first awareness of psychotic symptoms was used as the index of onset. Men had a significantly earlier mean age at onset (24 +/- 6) than the women (27 +/- 8). By the time they were 30 years of age, 83% of the men and 66% of the women had become ill. The findings are remarkably similar to those of an earlier report in the same cultural setting, and add to the evidence of sex differences in age at onset of schizophrenia.