A national study found that the poor are 60 percent more likely than higher-income Americans to suffer from migraines, debunking long-held perceptions that the intense and often disabling headaches are a rich person's disease, scientists said yesterday.
The study -- based on responses from more than 20,000 people of all races, income groups and geographic regions -- also found that women are three times more likely than men to get migraines. The reasons why remain largely a mystery.
Researchers, however, noted that almost 6 percent of men reported they suffered from at least one migraine a year, a large enough figure to deflate the widely held belief that women hold a near-monopoly on the affliction.
"Our hope is that there will be more recognition of migraines," said Dr. Walter F. Stewart, associate professor of epidemiology at the Johns Hopkins School of Hygiene and Public Health, said yesterday. "It is a very common, acutely disabling condition."
Although the study was limited to a statistical analysis of who gets migraines, Dr. Stewart speculated that the stress of surviving on limited money may predispose poor people to migraine headaches.
Also, he said the poor are less likely to visit a doctor for treatment. As a result, many may never get helpful medications that can stave off headaches for months at a time or learn to reduce symptoms by altering their diet or reducing stress.
Migraines, caused by a chemical imbalance in the brain, are marked by a throbbing, often one-sided pain that can be accompanied by nausea, vomiting, visual distortions and unusual sensitivity to light, noise or smells. They can be triggered by stress, hormonal changes or certain foods such as red wine, chocolate, cheese or citrus fruits.
Researchers at Hopkins and the Albert Einstein College of Medicine in New York estimated that 8.7 million women and 2.6 million men suffer from migraines -- projections based on questionnaires filled out by 20,468 people across the country. Subjects were between the ages of 12 and 80.
The study, appearing in today's Journal of the American Medical Association, is the first to focus on differences in migraine prevalence according to sex, age, race, geography and income.
Among the key findings:
* 17.6 percent of the women and 5.7 percent of the men said they had migraine symptoms at least once a year, a threefold difference.
* The migraine rate was 60 percent higher among Americans making less than $10,000 a year than it was among people earning more than $30,000.
* Rural and urban people suffered equally.
* Most sufferers have one or more attacks per month, and men and women who get migraines are equally likely to miss work or school.
While the male-female difference confirmed earlier studies, Dr. Stewart the research team was surprised by the differences among income groups.
"There's been a belief that migraine is a condition much more common among higher income groups," Dr. Stewart said. "You obtain this perception from the kinds of patients who come into ** your office. What we found was completely contrary to that."
Migraines can also drive people into lower-income brackets when headaches make it impossible for them to hold jobs or concentrate on school, said Dr. Richard B. Lipton, a neurologist from the Albert Einstein College of Medicine.
"On the day we discovered the income differences, I saw two patients," Dr. Lipton said. "One was a lawyer losing time due to migraines. She just messed up a major trial and was in a lot of trouble. I also saw a physics student who dropped out of college, because she was having migraines."
What causes women to suffer more frequently than men remains a mystery, although the researchers said hormonal cycles may be a minor reason.
While boys get migraines at an earlier age than girls do, the headaches are more likely to strike girls once they start menstruating in their early teens. The gap widens until age 42, when women are 3.5 times more likely to get migraines, but narrows after women enter menopause.
"But even when we look at age 75, when circulating hormones are no longer a factor, women are still twice as likely to suffer from migraines as men," Dr. Lipton said. "Most of the gender difference is not well understood."