Seasonal affective disorder and latitude of living.
OBJECTIVE
Since the importance of latitude of living for the prevalence of Seasonal Affective Disorder (SAD) is unclear, the study aims to test the latitude hypothesis by comparing SAD in two rather similar groups of students living at latitudes far apart.


METHODS
Two groups of students, 199 in Tromsø, Norway (690 N) and 188 in Ferrara, Italy (440 N) were asked to fill in the Seasonal Pattern Assessment Questionnaire.


RESULTS
Global Seasonality score (GS-score) was significantly higher in Italian than in Norwegian students, in females and in students with sleeping-problems. Norwegian students had significantly higher SAD prevalence in winter and in spring. Most people in both countries felt worst in October and November, and the prevalence of Autumn SAD was not significantly different between the two countries.


CONCLUSIONS
The hypothesis that SAD is linked to amount of environmental light and latitude of living was not supported.
Brancaleoni
Greta
G
Department of Clinical Psychiatry, Institute of Clinical Medicine, Faculty of Medicine, University of Tromsø, and Psychiatric Department, University Hospital North, Norway.
Nikitenkova
Elena
E
Grassi
Luigi
L
Hansen
Vidje
V
D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D009664:Norway / Q000453:epidemiology; D016574:Seasonal Affective Disorder / Q000453:epidemiology*; D055815:Young Adult