Age-at-onset and schizophrenia: reversed gender effect

Abstract

Objective: This study seeks an explanation for reversed gender effect on age-at-onset (AAO) in schizophrenia. The hypothesis is older AAO in males would be detected in a sample where higher infant mortality (IMR) prevailed. Method: Case records of International Classification of Diseases-10 (ICD-10) schizophrenia patients from two states (n=70 each) with an IMR of 13 and 67 per thousand were reviewed and AAO was obtained by using the recorded age and duration of illness. Results: In the sample from the state with lower IMR, AAO did not differ between the two sexes. However, men had older AAO than women in the state with fivefold higher IMR. Conclusion: Gender differences in AAO may be a function of perinatal complications. In places where infants with perinatal complications are less likely to survive, hence high IMR, a small group of potentially youngest AAO schizophrenic males may be eliminated thus changing the gender effect on AAO.