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.