Millions of women suffer from chronic headaches, with 90 percent of them experiencing migraines. As if that isn't difficult enough to deal with, a study showed that women with chronic headache were four times likelier to report symptoms of major depression than were those with episodic headache.

The women who reported the symptoms of major depression were three times more likely to have symptoms related to the headache, like low energy, trouble sleeping, nausea and other pains and problems. These painful physical symptoms could cause or provoke major depression, and depression can heighten pain perception.

While the cause of the link between headache and depression isn't entirely known, it is certain that one is related to the other, making the research and treatment of both all the more important.