MONTH OF BIRTH AND SCHIZOPHRENIA IN TAIWAN - EFFECT OF GENDER, FAMILYHISTORY AND AGE AT ONSET

Schizophrenic patients have been shown to have a moderate excess of wi nter births in the areas where seasonal variations in weather are larg e. In this report, we examined the seasonality of schizophrenic births in Taiwan, which has a subtropical climate. Using nationwide hospital ization data (2429 male and 1320 female schizophrenic patients), we ap plied the life table method to compare the risk of schizophrenia among 12 cohorts of month-of-birth for males and females, respectively. Dif ferences among the risks of the 12 cohorts were tested using the logra nk test. The samples were further stratified by family history and age at onset. There was a significant association between the risk of bei ng admitted as a schizophrenic and month of birth for both males and f emales. The cohorts born in November and January had the highest risks . After stratification, the association was significant only for non-f amilial, male, and early onset schizophrenic patients. The results ind icate that seasonally varying factors might increase the risk of schiz ophrenia, especially in those without a family history of the disease. Men are more vulnerable to such factors than women, and the schizophr enics resulting from such insults tend to be early onset.