GENDER-SPECIFIC DECLINE AND SEASONALITY OF BIRTHS IN OPERATIONALLY DEFINED SCHIZOPHRENICS IN ITALY

All clinical records of schizophrenic patients included in the period 1979-1995 in the South Verona Psychiatric Case Register were reviewed and diagnoses operationally defined according to ICD-10 criteria using OPCRIT 3.1. Among the 335 scrutinized, 205 patients met the ICD-10 cr iteria for paranoid or undifferentiated schizophrenia. No seasonality of birth was found in these patients using a log-linear equiprobabilit y model. The incidence and seasonality of birth were then analysed on the subsample of 106 patients born in 1947-1974 for whom corresponding data for the Verona general population were available. Schizophrenic males displayed a significant excess of birth in November-January with respect to the Verona population (chi(2) = 10.93, p = 0.012). The tim e series of the incidence of schizophrenia by cohort of birth 1947-197 4 had a linearly decreasing trend, steeper in males than in females. T he significant increase in age at first ever psychiatric contact, obse rved in both males and females throughout the period considered, canno t completely account for the gender-specific decline of birth of schiz ophrenics. (C) 1997 Elsevier Science B.V.