title: Season of birth in Japanese patients with schizophrenia.
abstract: A number of North American and European studies have observed a higher proportion of winter births in schizophrenia patients. Fewer studies have investigated this issue in Asian populations, and the findings are not as consistent as in the studies of Western populations. A statistically significant excess of winter births has not been observed in Japanese or Korean studies, while some of the studies found a decreased number of summer births among their patients. We further investigated the issue in Japanese patients with schizophrenia (n=2985). No significant excess of winter births was observed. Spearman correlation between schizophrenia births and ambient temperature was not significant. However, a decrease in the summer births was found, consistent with most of the previous Japanese studies. When analyzed by gender, a decrease in summer births was found in males, but not in females. In addition, a trend towards an increase in winter births was observed and Spearman correlation between low ambient temperature and schizophrenia births was significant in male subjects. More significant seasonality of birth in male patients than in female patients might be related to more susceptibility to pre- or perinatal disturbances in neurodevelopment in males than in females.
authors.affiliation: Department of Psychiatry, Showa University Fujigaoka Hospital, Kanagawa, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Tatsumi
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Sasaki
authors.forename: Akira
authors.initials: A
authors.lastname: Iwanami
authors.forename: Asako
authors.initials: A
authors.lastname: Kosuga
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tanabe
authors.forename: Kunitoshi
authors.initials: K
authors.lastname: Kamijima
mesh_terms: D017668:Age of Onset; D001723:Birth Rate; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000453:epidemiology*; D012621:Seasons; D017678:Sex Distribution; D018709:Statistics, Nonparametric; D013696:Temperature