Some sufferers have twice the chance of heart attacks, strokes, studies say
David Kohn
Beth Leslie had gotten occasional migraines for years. She thought of them as a painful imposition, nothing more.
Then, one day two years ago, her world tipped sideways. “Everything was spinning. I just kept my eyes closed, because whenever I’d open them I’d get dizzy,” says Leslie, a 24-year-old veterinary technician who lives in Bowling Green, Ohio. “It really freaked me out.”
She went to the hospital, where a doctor told her she’d probably come down with some sort of virus. After two days, Leslie’s condition hadn’t improved, and her boyfriend started pressing the doctors. They agreed to give her a brain scan, and found she’d suffered a stroke, one that centered on her cerebellum, the part of the brain in charge of balance.
Leslie was shocked. Like most people, she’d thought of stroke as a disease of old age. But for those who get migraines, the rules appear to be different. Until recently, scientists saw migraine suffering as a physiological thunderstorm that left few lasting effects. But new research suggests some migraines aren’t so innocuous.
Recent studies show those who suffer from something called migraine with aura have double, or perhaps triple, the risk of stroke or heart attack, compared with people who don’t get migraines at all.
In these people — Leslie is one of them — the headache is preceded by a range of symptoms: slurred speech, forgetfulness, feeling hot or cold, and ghostly lights blinking across the field of vision. That last one is the aura. A third of those who experience migraines have these symptoms; generally, this sub-group also has more frequent, and more excruciating, migraines.
“I don’t think migraine is seen as a serious disorder. That’s a mistake,” says migraine researcher David Dodick, a neurologist at the Mayo Clinic in Phoenix. “Headache is just one manifestation of migraine. It’s a systemic illness.”
The mysteries of migraines
Thirty-five million Americans — 1 in 10 of us — get migraines. They tend to occur regularly, with severe pain on one side of the head. Migraine attacks often include other symptoms, such as nausea and sensitivity to light and sound.
Researchers disagree on whether people who get migraines without aura are at higher risk for strokes and heart attacks. So far, almost all of the research of migraine and cardiovascular risk has occurred in those who get auras.
And one knows for sure what accounts for the higher rates of strokes and heart attacks in those who do suffer from migraine with aura, but scientist have several theories that may offer insight.
Some researchers blame migraines on chronic exposure to certain neurotransmitters. Most scientists think migraine sufferers’ brains are hyper-excitable — that is, their neurons tend to start firing uncontrollably, with the outburst spreading across the brain over the course of a few hours.
This electrical storm causes the brain to release several neurotransmitters, including two chemicals called Substance P and Calcitonin Gene-Related Peptide (CGRP), that produce inflammation and pain in the blood vessels surrounding our brains.
Researchers suspect that over years of repeated migraines, the inflammation from Substance P and CGRP may weaken blood vessels, not only in the head but throughout the body. This damage may raise the risk of stroke or heart attack. During a stroke, the vessels that supply the brain rupture or become blocked; during a heart attack the same thing happens to the vessels around the heart.
In a study of 175 people completed last year, University of Toledo neurologist Gretchen Tietjen — who treated Leslie after her stroke — found that nearly a third of those with migraines had signs of blood vessel damage, almost five times higher than the controls.
Tietjen says that while there’s no conclusive proof that Leslie’s migraines played a role in her stroke, they easily could have.
But another group of scientists think the culprit isn’t neurotransmitters, but the vascular system itself. Dodick and others argue that the blood vessels of people who get migraines are inherently dysfunctional, contracting and expanding abnormally in reaction to physical and emotional stress.
“People with migraine probably have unusually reactive blood vessels,” says neurologist Richard B. Lipton, a leading migraine researcher at the Albert Einstein College of Medicine in the Bronx.
In the head, these vascular spasms could trigger migraines. When the veins and arteries in the temple and skull expand and contract too much, they may press on nerves, leading to the excruciating pain.
In people who get migraines, these blood vessel seizures may occur throughout the body, without patients much noticing. Over years, these spasms may damage the vascular system.
Link between migraine and heart defect?
Then there’s the hole-in-the-heart theory. Researchers have known for years that having a gap in the wall between two chambers of the heart — a surprisingly common defect (it occurs in 10 to 20 percent of people) — increases the risk of stroke. It’s not clear why: The defect, known as a patent foramen ovale, or PFO, may allow blood to bypass the lungs, which constantly filter small clots and impurities from the blood. These clots may end up lodged in veins and arteries in the head, triggering strokes.
Over the past five years, scientists have found that PFOs seem to occur in more than half of people who get migraines. In some migraine patients, closing the PFO with surgery seems to lead to a disappearance of headaches.
Some researchers suspect the unpurified blood leaking through the PFO contains inflammatory molecules, which set off that electrical storm when they travel up to the brain. (This may be why people with migraine get headaches after eating certain foods like red wine, olives and chocolate. These “trigger” foods may contain the offending chemicals, which in normal people are constantly removed from the blood.)
‘A very complex system’
But none of these hypotheses have been proven, and the links between migraine and cardiovascular disease remain murky.
“There’s no clear mechanism that convinces me,” says Tobias Kurth, a neuro-epidemiologist at the Harvard University School of Public Health. “It’s likely a very complex system.”
Kurth, who has spent several years examining connections between migraine and stroke, thinks there may be several lines of connection between stroke, heart disease and migraine.
At the same time, he says, even those who get frequent migraines shouldn’t panic. In the general population, stroke and heart attack are quite rare. They’re even less common if you’re young and healthy. While th e stroke risk might double from 15 per 100,000 in the general population to 30 per 100,000 for those who migraine with aura, the risk is still relatively small, pointed out Lipton in the journal Neurology Today.
“A doubling of risk sounds scary, but in absolute terms, it’s still low,” says Dr. Stephen Silberstein, a migraine specialist at the Jefferson Headache Center in Philadelphia.
But if you get migraines, and you smoke, are overweight, or have untreated high blood pressure, then your risk climbs significantly. And each risk compounds the others exponentially.
In a 2007 study published, Kurth found that women who have migraine with aura, smoke and take oral contraceptives (also a stroke hazard), were 10 times more likely to have a stroke than women without these risks. Leslie, for example, was taking birth control pills when she had her stroke.
Changes in treatment
Even without a clear causal link, the new findings may change how doctors treat migraines. Rather than seeing the condition as a painful but harmless hassle, doctors are increasingly trying to prevent it, just as they do obesity or high blood pressure. A range of medicines, including blood pressure drugs and antidepressants, can help prevent headaches. And many patients also find relief through changes in lifestyle and diet.
Although there’s no clear proof, some scientists, including Tietjen, suspect that in migraineurs, preventing headaches could lower the risk of stroke and heart attack.
“I think there’s ongoing, progressive damage to the cardiovascular system,” she says. “If you can treat patients early on, maybe you can keep it from progressing.”
Dodick agrees. “The evidence points in that direction,” he says. “So it makes good sense to be aggressive with preventive measures.” He notes that only 15 percent of people who get frequent migraines take preventive medicine.
Leslie, who has since fully recovered from her stroke, is now in this minority. She takes Elavil, an anti-depressant, for migraine prevention. She no longer takes oral contraceptives, and last year she had surgery to close a PFO doctors discovered after her stroke. She almost never gets a headache.
“It still surprises me that I had a stroke,” she says. “But I’m doing everything I can to stay healthy now. I’ve come a long way.”
David Kohn is a health and science writer. His work has appeared in The New York Times, Popular Science, on BBC's The World and on National Public Radio.
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