Season of birth in mental disorders in Tokyo, Japan, by year of birth, year of admission and age at admission.

Seasonal distribution of births of schizophrenics and manic-depressives born in Tokyo between the years of 1841 and 1940 and first admitted between 1879 and 1973 was examined by year of birth, year of first admission and age at first admission. In both mental disorders, a fall-excess of births could be seen among those born up to the latter part of the 19th century, after which the distribution changed to show a spring-excess. The distributional pattern seemed to depend upon both year of birth and year of admission, rather than on age at first admission.