Migraines accompanied by visual problems called auras double the risk that women will develop cardiovascular disease later, a new study by Harvard doctors suggests.
Dr. Tobias Kurth and colleagues at the Harvard School of Public Health and Brigham and Women's Hospital analyzed records from 27,800 women older than 45 who participated in the Women's Health Study. All were free of cardiovascular disease when they entered the study between 1992 and 1995.
Ten years into the Women's Health Study, there were 580 major cardiovascular events among the 5,125 volunteers with a history of migraines. The scientists discovered that women with migraine aura had more than double the heart risk of those without an aura.
An aura is a visual sensation -- such as lights flashing or lines zigzagging, with some reports of temporary blindness -- that lasts 20 minutes to an hour. Then, a penetrating headache comes on, which can also trigger nausea and vomiting. This can continue for hours, and in some cases up to three days.
Kurth said there were no solid clues to explain the link. One idea is that some people who suffer from migraines are born with a heart defect that increases the risk of blood clots that can travel to the brain and cause strokes.
Women with migraines who never experienced auras had no greater risk for heart disease or stroke than the rest of the population.
Kurth said the migraine risk was small, and there were more serious threats to heart health -- such as high cholesterol, smoking, diabetes and obesity -- that could be modified with lifestyle changes or treatment.
Having migraines with auras adds about 18 additional cases per 10,000 women a year, Kurth said.
Researchers are evaluating this association in males.
The Harvard study was published in the July 19 issue of the Journal of the American Medical Assn. two weeks after its editors announced stricter enforcement of a policy requiring study authors to disclose potential conflicts of interest.
According to JAMA editors, all six of the scientists involved in the study have done consulting work or received unrestricted research grants from makers of treatments for migraines or heart-related problems.
Kurth said they had decided not to note the affiliations because the current study had nothing to do with medicines for migraines and had not been funded by a pharmaceutical company.
Still, Dr. Catherine DeAngelis, JAMA's editor in chief, said she would have published the authors' associations with drug makers had she known about them.
On Tuesday, the Harvard scientists sent the journal an extensive list of all of their collaborations with the pharmaceutical industry.
"Authors should always err on the side of full disclosure," DeAngelis wrote in her response.