Wednesday, January 13, 2016
Depression is much more common in the winter in Canada
Discussions about winter depression in this country tend to gravitate towards the concept of Seasonal Affective Disorder (SAD). SAD is not officially recognized as a disorder in DSM-5, but is instead a subtype of Major Depressive and Bipolar Disorders. The way in which the sub-type is defined in the manual is based on episodes having a characteristic time of onset and resolution. They are not required to occur in the winter and they are not even required (in the case of Bipolar I disorder) to be depressive episodes. Most studies of this condition have used instruments that assess seasonal variation in mood, not depressive episodes. But it is important to know whether there is actually more major depression in the winter months. We've recently looked at this question in national datasets and the results are striking (click here). The paper is published in the journal Epidemiology and Psychiatric Sciences. There is a 70% higher odds of depression in the winter months compared to the summer months. This presents a real problem for the health system(s) in Canada to deal with, since it implies a need for greater availability of services in the winter months - and I know of no efforts to deliver seasonal services for depression.