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Seasonality of schizophrenia births in the Japanese population: increased winter births possibly confined to the north area

journal contribution
posted on 15.06.2005, 00:00 authored by M Tochigi, T Onai, K Narita, H Hibino, Mark RogersMark Rogers, T Umekage, K Kohda, T Otani, R Kanamori, N Kato, T Sasaki
A number of North American and European studies have observed a higher proportion of winter births in schizophrenia patients. Thus, seasonal fluctuation of unknown environmental factors may affect brain development in ways that alter susceptibility to schizophrenia. Specification of these factors may help elucidate the etiopathological mechanism of the disease, about which little is certain. A small number of studies have investigated this issue in Asian populations, and the findings are not as consistent as those of Western populations. No remarkable excess of winter births has been observed in Japanese or Korean studies, while some studies have reported a significant decrease of summer births. We further investigated the issue in Japanese patients with schizophrenia (n=3927). No significant excess of winter births was observed, but a decrease in the summer births was found in male subjects. This is largely consistent with previous Japanese studies; however, when the subjects were confined to those born in a colder and higher latitude area of Japan (n=1338), a consistent trend for both a winter increase, and a summer decrease, was found. However, the results did not consistently reach statistical significance, possibly due to the lack of statistical power. Environmental factors that correlate with latitude might play a role in the development of the seasonality of births in schizophrenia. Further studies in a larger sample size are required to test these possibilities.

History

Journal

Schizophrenia research

Volume

75

Issue

2-3

Pagination

433 - 438

Publisher

Elsevier

Location

Amstersdam, The Netherlands

ISSN

0920-9964

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2004, Elseiver