By Denise Mann
WEDNESDAY, Jan. 13, 2009 (Health.com) — People who tend to get migraines are also at risk for depression, and the reverse is true as well—if you’re depressed, you’re more likely to get the killer headaches.
Now, a new study suggests that the link may be due to an underlying genetic propensity that increases the risk of both conditions, rather than one causing the other. (Some researchers have speculated that the stress of migraines might lead to depression, or that migraines are a symptom of depression.)
Anine H. Stam, MD, a neurologist at Leiden University Medical Center in the Netherlands, and colleagues made the discovery by looking at a unique group of people—2,600 Dutch citizens descended from just 22 couples. Because the study participants were so closely related, the researchers were able to trace genetic connections that typically can only be found by studying individual families or twins.
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The researchers found that people who experienced migraines were 43% more likely to be depressed than people who were migraine-free. And people who had migraines with aura (visual disturbances such as flashing lights) were even more likely to be depressed—they had a 70% greater risk than their headache-free peers. (The overall rates of migraine and depression in the study were comparable to those in the general population.)
The researchers calculated that 77% and 96% of a person's susceptibility to migraines with and without aura, respectively, is due to genetic rather than environmental factors (which is known as heritability). When they looked at the heritability of depression in people with or without the headaches, they found a strong genetic link between the two conditions, according to the study, which was published in the journal Neurology.
Next page: Not all experts are convinced
If the study findings are confirmed in larger populations, the next step would be to try to pinpoint the gene (or more likely, genes) that trigger migraine. More than 29.5 million Americans suffer from migraines, which are characterized by pain (usually on one side of the head), nausea or vomiting, and increased sensitivity to light or sound. About 15 million American adults are clinically depressed.
Seymour Diamond, MD, the executive chairman of the National Headache Foundation, says that despite the study's findings, the jury is still out on whether migraine and depression share an underlying genetic cause. “There may be a genetic link between some migraine types and depression, but this study needs more elaboration before you would say there is an absolute genetic link between the two conditions,” he says.
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Dr. Diamond also emphasizes that the study does not show that migraines are inevitable in depressed people, and vice versa. “This does not mean that if you have depression, you will have migraines, or if you have migraine, you will have depression,” he says. “There is a certain subgroup that this occurs in, and even that is not a given.”
Genetic testing for migraine susceptibility is still a ways off, but in the meantime, if you have symptoms of depression or migraine, discussing your family history with your doctor may increase your chance of receiving an accurate diagnosis, especially if your symptoms are borderline, says Andrew H. Ahn, MD, an assistant professor of neurology at the University of Florida College of Medicine, in Gainesville, Fla., who co-authored an editorial that accompanied the new study.
“For people with clear-cut migraine or depression, the presence of a family history does not add a lot to the diagnosis or care,” he says. “However, in those in whom the diagnosis is uncertain, obtaining a thorough and careful family history could be extremely helpful.“