Seasonality of mania: a Tasmanian study.
OBJECTIVE
The aim of the study was to examine the seasonal incidence of mania in a new Southern Hemisphere location.


METHODS
Using the Tasmanian psychiatric database, monthly admission rates were compared with expected admission rates for mania for the period 1983 to 1989. ICD-9 criteria for mania single episode (296.0) and mania recurrent episodes (296.1) were used, excluding individuals with a bipolar disorder (296.4 to 296.89).


RESULTS
One thousand three hundred and twenty-eight persons were admitted during this period. There was a significant monthly variation with admissions occurring most commonly in the summer, but this was not consistent during the seven year period.


CONCLUSIONS
There was a statistically significant but inconstant summer excess. The inconstancy of the finding suggests that the phenomenon is not a simple consequence of light duration, and closer examination of these inconsistencies may lead to further elucidation of the phenomenon.
Jones
I
I
Department of Psychiatry, University of Tasmania, Hobart.
Hornsby
H
H
Hay
D
D
D000293:Adolescent; D000328:Adult; D000368:Aged; D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008027:Light; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data; D012008:Recurrence; D012621:Seasons; D013648:Tasmania / Q000453:epidemiology