Is migraine in unipolar depressed patients a bipolar spectrum trait?

Background: It is well known that affective disorders and migraine often coexist in the same patients, and some information is available indicating that migraine is particularly prevalent in bipolar II disorder. The aims of this study were to compare the clinical features in unipolar depressed patients with and without comorbid migraine to bipolar patients. Methods: Semi-structured interview of 201 patients with major affective disorders, using DSM-IV criteria for affective disorders combined with Akiskal's criteria for affective temperaments, and IHS-criteria for migraine. Results: Compared to the group of patients having unipolar depressions without comorbid migraine (n=51) the group with unipolar depression and migraine (n=63) had a higher number of depressive episodes (4.5 vs. 2.5, P=0.017), significantly higher prevalences of affective temperaments (46% vs. 16%, P=0.001), irritability (70% vs. 45%, P=0.008), seasonal variation (22% vs. 5%, P=0.017), agoraphobia (44% vs. 26%, P=0.036), asthma (25% vs. 6%, P=0.006) and migraine in family (59% vs. 29%, P=0.002). The clinical features of unipolar depressed patients with comorbid migraine resemble the bipolar II patients (n=51) in this sample. Limitations: Non-blind, cross-sectional assessment. Conclusions: These results indicate that there may be important clinical differences between unipolar depressed patients with and without comorbid migraine, possibly indicating that migraine in depressed patients is a bipolar spectrum trait.