Influence of season and latitude in a community sample of subjects with bipolar disorder.
OBJECTIVE
To report on the prevalence of seasonal bipolar disorder (BD) and the impact of latitude in a community sample in the province of Ontario.


METHODS
This study used the telephone-administered Depression and Seasonality Interview. Exact latitude was determined for each participant.


RESULTS
Overall, 14 of 62 (22.6%) subjects with BD had the seasonal subtype of BD. Latitude did not appear to influence the proportion of subjects with the seasonal subtype.


CONCLUSIONS
We identified a seasonal pattern of illness in a proportion of subjects with BD.
Schaffer
Ayal
A
Department of Psychiatry, University of Toronto, Mood Disorders Program, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario. ayal.schaffer@swchsc.on.ca
Levitt
Anthony J
AJ
Boyle
Michael
M
D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D015995:Prevalence; D012111:Residence Characteristics; D012621:Seasons