Brain lesions, or changes in the white matter of the brain, may develop at a higher rate in women who get migraines than in women who don't, according to a new study in the Journal of the American Medical Association.
The study researchers had previously found in 2004 that while some people who don't get migraines also have these brain changes, there is a higher prevalence of the changes, called white matter hyperintensities, in women with migraines than in those without.
Their new findings reveal that these changes develop more often in women affected by migraines.
"After [nine] years follow-up, the prevalence of white matter changes is still higher in female migraine patients, but also the number of new lesions was higher," study researcher Dr. Mark C. Kruit, M.D., of Leiden University Medical Center, told HuffPost.
However, he added that there were no cognitive differences found between people with migraine and those without, and the white matter changes that were found were small, so people with migraines should not be worried by the new findings.
Kruit noted that brain lesions -- while scary sounding -- can also be thought of as small spots of scars in the brain. The same risk factors for conditions like ischemic stroke, such as high blood pressure or cigarette smoking, are also considered risk factors for these white matter hyperintensities. A review of studies in the British Medical Journal in 2010 showed that white matter hyperintensities are linked with higher risks of death, dementia and stroke, and possibly cognitive functioning and brain processing speed.
"Therefore most often white matter hyperintensities are considered to be 'ischemic' in origin. However, sometimes similar lesions have an inflammatory, infectious or toxic cause," Kruit said. "It is unknown what the exact cause of the [white matter hyperintensities] in migraine patients is."
The new study, which was conducted by Kruit along with his colleagues Drs. Inge Palm-Meinders and Hille Koppen, in collaboration with the U.S. National Institute on Aging, included 295 people with migraine and 140 people without migraine. Of the 295 people with migraine, 203 underwent MRI brain scans, and among the 140 people without migraine, 83 underweight MRI brain scans. Researchers followed up with them nine years later.
They found that women with migraines were more likely to have developed new lesions over the nine-year follow-up period. Specifically, 77 percent of the women with migraine experienced brain white matter changes by the end of the study period (112 out of 145) compared with 60 percent of the women without migraine (33 out of 55).
"These figures mean that female migraine patients are [two] times more likely to develop new lesions, compared to female controls," Kruit said.
The researchers noted that people who had migraines, but who only had a few attacks over the study period, still experienced the brain changes. "Based on this, it seems that the effect on the brain is mainly attributable to the disease migraine, rather than to having repetitive migraine attacks," the researchers wrote in a release.
They also found an association between infarcts (which are clusters of dead brain cells) and migraines. In 2004, researchers noted that 8 percent of people with migraines had infarcts (which is already seven times higher than people who don't have migraines). But in the new study, new brain infarcts developed in 5 percent of people with migraines, while no new brain infarcts developed in people without migraines.
However, there was no link found between migraine frequency, migraine aura or migraine management and the brain lesions, nor did researchers find any real cognitive differences between people with and without migraine, Kruit said.
"The findings imply that small white matter hyperintensities in most patients with migraine should not be a reason for alarm," wrote Dr. Deborah I. Friedman, M.D., M.P.H., of the University of Texas Southwestern Medical Center, and the Mayo Clinic's Dr. David W. Dodick, M.D., in an accompanying editorial.
"However, given the relationship between migraine and several acquired and genetic vasculopathies, it is possible that certain subpopulations of patients with migraine with white matter hyperintensities may be at an increased genetic risk for significant white matter disease and neurological morbidity, including stroke, transient ischemic attack, cognitive impairment, and other neurologic outcomes," they wrote.
This is not the first time migraine has been linked with a risk factor for stroke. A review of studies in the American Journal of Medicine in 2010 showed a doubled risk of stroke due to blood clot among people who get migraines, Reuters reported.
The researcher of that study, Dr. Saman Nazarian, who is an assistant professor at Johns Hopkins University School of Medicine, told Reuters that it's not completely clear why migraines seem to be linked with the increased stroke risk, but that people who get migraines should just be extra careful about making sure they keep the stroke risks they can control, like blood pressure, low.