Middle-aged people who experience migraine headaches may be more likely to develop Parkinson's disease or other movement disorders later in life, a new study says. And people who have migraines with visual auras could have double the risk of developing the disease, according to the study, published today in Neurology.
"Migraine is the most common brain disorder in both men and women," said study author Ann Scher, Ph.D., of Uniformed Services University in Bethesda, Maryland, in a press statement. She said other studies have also linked migraines with cerebrovascular and heart disease.
“This new possible association is one more reason research is needed to understand, prevent, and treat the condition,” she said.
The study followed 5,620 people between the ages of 33 and 65 for 25 years. At the time the study was launched, 3,924 of the participants had no headaches, 1,028 had headaches with no migraine symptoms, 238 had migraines with no aura, and 430 had migraines with aura. The researchers wanted to see who might later show Parkinson’s symptoms or symptoms of restless leg syndrome (RLS), also known as Willis-Ekbom disease.
The researchers say that people who had migraines with aura at the start of the study were more than twice as likely to be diagnosed with Parkinson's as people who did not experience headaches. In fact, 2.4 percent of people who experienced migraines with aura developed Parkinson’s, compared to 1.1 percent of those without headaches.
Those who had migraines with aura had 3.6 times the odds of reporting at least four symptoms of Parkinson’s; those who had migraines with no aura had 2.3 times the odds of showing symptoms, which include tremors and difficulty communicating.
The researchers noted that women who had migraines with aura were more likely to have a family history of Parkinson's disease than people who had no headaches at all.
What causes migraines? Researchers aren’t quite sure. Scher said that a problem with the brain messenger chemical dopamine is common in patients with Parkinson's and RLS, and scientists suspect it may be the cause. She would like to see more research exploring the link between the two.
Dawn Buse, Ph.D., an associate professor of neurology at the Albert Einstein College of Medicine at Yeshiva University and a fellow of the American Headache Society, said researchers are still learning about what causes migraines.
“It is believed to be a neurologic disorder with a genetic predisposition which may interact with the environment,” she said.
Buse said that migraine attacks may be caused by changes in the brainstem and its interactions with the trigeminal nerve, which is an important pain pathway. The trigeminal nerve runs from the temples to behind the eyes and also controls the function of the jaw.
Serotonin and other chemicals that help regulate pain in the nervous system may be involved in the attacks as well. Researchers have speculated that serotonin levels drop during migraine attacks, causing the trigeminal system to release neuropeptides and other chemicals.
Buse said that Scher’s large sample size and long follow-up period of 25 years make hers a valuable study for other researchers to learn from.
However, Scher warns patients not to be fear that migraines mean they will necessarily develop Parkinson’s or RLS.
"While the history of migraine is associated with an increased risk for Parkinson's, that risk is still quite low," she said.