Researchers at the University of Toledo Health Science Campus, in Ohio, found women who had chronic headaches (more than 15 headaches per month) had a 4-fold increased risk of depression compared with women with episodic headaches (fewer than 15 headaches per month).
The investigators also found women in the chronic group were 3 times more likely to report a high degree of headache-related symptoms, including fatigue, insomnia, nausea, dizziness, pain, or problems during sexual intercourse.
Furthermore, among patients diagnosed with severely disabling migraine, the study showed the likelihood of major depression increased 32-fold if the patient also reported other severe physical symptoms.
The study is published in the January 9 issue of Neurology.
Although the link between migraine and depression has been reported in previous research, this is the first prospective study to examine the relationship between migraine, depression, and somatic symptoms.
"There's been a lot written on chronic headache and depression but not much written on chronic headache and somatic symptoms. If we can figure out how these 3 things tie together physiologically, it may give us greater insight into how to better manage these patients," the study's principal investigator, Gretchen Tietjen, MD, told Medscape.
The study included 1032 women from 6 headache clinics across the United States — 90% of whom were diagnosed with migraine. Of the total study group, 593 subjects reported episodic headache and 439 were in the chronic group.
Between June 2003 and December 2004, subjects completed a questionnaire that gathered information on demographics, age at headache onset, headache-related disability, somatic symptom, and depression severity. Investigators then measured the associations between headache frequency and headache-related disability with somatic symptom and depression severity.
According to the results, 72% of the entire study population reported having very severe headache impact, with a higher proportion in the chronic headache group — 88%, vs 60% in the episodic group.
In the overall study population, somatic symptom severity as measured by the Patient Health Questionnaire-15 (PHQ-15) was reported by study subjects as high in 31%, medium in 39%, low in 27%, and minimal in 4%.
Of the 14 nonheadache symptoms included in the PHQ-15, 11 were more common in subjects in the chronic headache group and 8 were significantly associated with chronic headache. These included: stomach pain; back pain; dizziness; pain or problems during intercourse; constipation, loose bowels, or diarrhea; nausea, gas, or indigestion; feeling tired or having low energy; and trouble sleeping.
Using the Patient Health Questionnaire-9 to assess depression, the study showed the prevalence of major depressive disorder for the entire group was 18%.
However, compared with those with episodic headache, chronic headache sufferers were 4 times more likely to report symptoms of major depression and almost twice as likely to present with symptoms of other depressive disorders.
"Sometimes symptoms of depression or other physical symptoms are not that obvious and often don't emerge in the course of a brief evaluation. In our headache clinic, I've been surprised at how many times, once I begin talking to a patient, they meet depression criteria. A screening tool provides a quick and effective way to pick up these kinds of symptoms and could ultimately result in better management of these patients," said Dr. Tietjen.
This study, said Dr. Tietjen, is the first from the research consortium of the American Headache Society Women's lssues section on depression, somatic symptoms, and domestic violence in headache.
Future studies will include examination the relationship of abuse, particularly childhood abuse, and migraine.
"There's a lot of interesting literature showing that traumatic events early in life can reset your stress thermostat, so that later on if you have stressors it makes you more likely to develop a lot of these chronic conditions, including migraine," she said.
In addition, Dr. Tietjen and her team also plan to look at whether there are genetic differences in patients with migraine, severe physical symptoms, and major depression.
"We plan to look at these same parameters in greater detail to see whether polymorphisms in the serotonin genes may cause some people to have a greater susceptibility to these conditions," she said.