Gender differences in age at onset of schizophrenia

Objective: To evaluate the gender differences in age at onset of schizophrenia. Design: Prospective case control study. Place and duration of study: Department of Psychiatry, Aga Khan University Hospital, Karachi between January to December 2002. Patients and methods: Sixty patients admitted consecutively to psychiatry ward and meeting the inclusion criteria were enrolled for the study. Age at onset of illness was defined as age at onset of gross psychotic symptoms, age at first contact with psychiatrist and age at index admission. Statistial method included two independent samples t-test. Data was dichotomized into those with family history of schizophrenia versus those without family history of illness and then Chi-square test of association was applied. Results: The mean age of onset of illness was 23.96 years in females and 24.13 years in males. In all other measures used to assess the onset of illness, females were overrepresented at the younger age group. 56.7% patients had a family history of psychotic disorder. Among them the mean ages at onset of illness were 20.59 years in females and 21.85 years in males ( χ 0.04 df=58). The illness occurred at a younger age in those with positive family history of schizophrenia (21.22 years) than those without it (25.14 years) with dissipation of gender difference in the former. Conclusion: There was no significant gender difference in age at onset of disorder in this study. Family history of schizophrenia appears to be the most significant factor that eliminates the gender differences in age at onset of schizophrenia.