Comorbidity of major depression and migraine--a Canadian population-based study.

OBJECTIVE To estimate the prevalence of major depressive episodes (MDEs) in patients with migraine and to compare the strength of association with that of other long-term medical conditions. METHODS This study used a large-scale probability sample (over 130,000 sample) from the Canadian Community Health Survey (CCHS), a cross-sectional survey conducted by Statistics Canada. The CCHS screened for a broad set of medical conditions. Major depression was evaluated with the Composite International Diagnostic Interview Short Form for Major Depression, and the diagnosis of migraine was self-reported. The annual prevalence of major depression was calculated in the general population, in subjects with migraine, and in those with chronic conditions other than migraine. RESULTS The prevalence of major depression in subjects reporting migraine was higher than that in the general population or in subjects with other chronic medical conditions (17.6%, compared with 7.4% and 7.8%, respectively). CONCLUSIONS There is a strong association between major depression and migraine. The migraine-MDE association may account for a large fraction of the chronic condition-MDE association. The association between migraines and MDE differs from that of other chronic conditions, as the association persists into older age groups.