Two seemingly unrelated problems might share a genetic component that may make some people more likely to suffer from both migraine and depression, Dutch researchers report.

The connection between migraine and depression has been examined before, but these researchers show that genetics may be the missing link between these two conditions.

"Migraine and depression co-occur far more frequently within subjects than to be expected by chance," said lead researcher Dr. Gisela M. Terwindt, an assistant professor of neurology at Leiden University Medical Center. "This relationship is bidirectional; migraine patients have an increased risk to develop depression and, vice versa, depressed subjects have an increased risk of getting migraine attacks," she said.

The report is published in the Jan. 13 online edition of Neurology.

For the report, Terwindt's team collected data on 2,652 people who took part in the Erasmus Rucphen Family study and were all descendants of 22 couples who lived in Rucphen in the 1850s to 1900s.

Among these people, 360 suffered from migraine, 151 of them had migraine with aura, and 977 had depression. In the latter type of migraine, the headache is preceded by flashes of light. Twenty-five percent of those with migraines also suffered from depression, compared to 13 percent of those without migraines, the researchers found.

Using this data, Terwindt's group was able to estimate the genetic contribution to both migraine and depression. They found that genetics explained 56 percent of all migraine. For migraine with aura, genetics accounted for 96 percent.

In addition, when they looked at the genetics of having both migraine and depression, the researchers found a shared genetic component, particularly for migraine with aura, Terwindt said. "Migraine patients have, at least partly, a genetic predisposition for depression," she noted.

In the future, knowing the genetics of these conditions may lead to better treatment and possibly prevention, she said.

"Identification of common genetic factors may significantly improve the insight into the molecular basis of both migraine and depression," Terwindt said. "This may help in the future to get more insight in the common pathophysiological process underlying both of these disabling disorders. This will, hopefully, lead to prevention of chronic migraine and development of tailored prophylactic treatments."

Dr. Gretchen E. Tietjen, chairwoman of neurology and director of the Headache Treatment and Research Program at University of Toledo Medical Center in Ohio, said that while genetics play a part in both migraine and depression, it may well take an environmental trigger to actually produce either condition.

Tietjen recently published a series of studies that found that children who experienced abuse or neglect were more likely to suffer from migraine and depression as adults.

"Physical, emotional or sexual abuse, and physical and emotional neglect were strongly tied to depression and other conditions that are found with migraine," she said.

Tietjen noted that stress in early life can permanently change the brain.

"Genetics is really important, and environment probably is important for turning some of these things on," she added.