SEATTLE— A study by Naomi Breslau, PhD, a Professor of Psychiatry at Henry Ford Hospital in Detroit, and colleagues challenged the widespread belief that major depression in migraineurs is simply a psychological response to migraine and showed that the migraine/depression link is bidirectional. The two disorders probably have common etiologies, suggested Dr. Breslau at the 44th Annual Scientific Meeting of the American Headache Society.

GROUP ASSIGNMENTS

The two-year study included 4,765 randomly identified Detroit-area residents ages 25 to 55—the age-group with the highest migraine incidence. These subjects responded to questions in personal and phone interviews about the number and type of headaches they had in the past 12 months. Based on their responses, eligible subjects were assigned to one of three groups.

Those who met the International Headache Society (IHS) criteria for migraine were assigned to the migraine group while those who reported non-migraine headaches similar in duration to and at least one third the severity of a migraine made up the severe headache group. The subjects in the latter group did not meet IHS criteria for migraine, Dr. Breslau stressed, nor did they report nausea, vomiting, or any other hallmark migraine symptoms with their headaches. Finally, subjects who said that they never had a migraine or severe headache formed the control group. Like the severe headache group, the controls did not report any migraine hallmarks. Subjects in all groups had to meet DSM-IV criteria for major depression to be diagnosed with that disorder.

HOW THE DISORDERS AFFECT EACH OTHER

The analysis of major depression’s effect on migraine risk included only the controls, since they were migraine-free initially. Their migraine incidence during the two-year follow-up was 9.3% when major depression was present at baseline versus only 2.9% in the absence of such depression. The sex-adjusted odds ratio for migraine among controls with baseline major depression was 3.4. Clearly, “[major] depression does predict migraine,” Dr. Breslau remarked. It does not predict severe headache, however.

When assessing major depression risk in the two headache groups, the investigators excluded the subjects with major depression at baseline. “We were not interested in [depression] recurrence,” explained Dr. Breslau. The exclusions markedly decreased the size of the two groups, by almost half, she acknowledged.

Analysis revealed an odds ratio of 5.8 for major depression among subjects with baseline migraine. In contrast, severe headache at baseline was associated with only a small increase in major depression risk that was not statistically significant.

Neither migraine nor severe headache influenced major depression recurrence during follow-up. “Once you have depression, it seems to follow its own course,” Dr. Breslau said. Migraine’s course likewise appeared to be independent of a history of major depression.

Notably, major depression at baseline did not have nearly as robust an effect on migraine as it did in the control group, producing only a small, nonsignificant increase in the risk. It did not exacerbate migraine-associated disability, she added.

A SHARED ETIOLOGY?

Major depression is not just a psychological response to migraine, as many in the medical community believe, asserted Dr. Breslau. If that were true, she said, then there should also have been an increased prevalence of major depression in the severe headache group since that group’s pain duration and severity were similar to those of the migraine group.

The fact that no such increase was observed supports the argument that migraine and major depression have a shared etiology. “Otherwise, you really have to come up with some very complex explanation as to how migraine could influence depression and then depression could influence migraine through another type of mechanism,” Dr. Breslau concluded.

—Timothy Begany

Suggested Reading
Breslau N, Rasmussen BK. The impact of migraine: epidemiology, risk factors, and co-morbidities. Neurology. 2001;56(6 suppl 1):S4-S12.

Breslau N, Schultz LR, Stewart WF, et al. Headache and major depression: is the association specific to migraine? Neurology. 2000;54:308-313.

Breslau N, Schultz LR, Stewart WF, et al. Headache types and panic disorder: directionality and specificity [erratum appears in Neurology. 2001;56:1124]. Neurology. 2001;56:350-354.

Return to table of contents