The migraine results also indicated that there was no increased risk of stroke associated with overall migraine and migraines without aura or non-migraine headache, according to lead study author Tobias Kurth, MD, ScD of the Division of Preventive Medicine at Brigham and Women's Hospital at Harvard Medical School.
Previous retrospective studies have produced mixed results on the effect of headache and migraine on risk for stroke.
To gain further insight into this question, Dr. Kurth and colleagues performed a prospective analysis of almost 40,000 women enrolled in the Women's Health Study, an ongoing trial examining the effects of aspirin and vitamin E on cardiovascular disease and cancer.
During an average of 9 years of follow-up, women who had migraine with aura had a 50 percent increased risk for total stroke and a 70 percent increased risk for ischemic stroke, compared to women without migraine. The risk was higher in women under 55 years of age. There was no increased risk for women who had migraine without aura, or non-migraine headache.
Aura is a sensory phenomenon that may precede the onset of migraine. Ischemic stroke is due to loss of blood supply to part of the brain. Both are neurovascular conditions, but the mechanism by which aura might influence ischemic stroke is still not resolved.
"In contrast to the established association between lipid levels and coronary heart disease, epidemiologic studies have not clearly established lipid levels as risk factors for ischemic strokes," said Kurth. His group examined this question in almost 28,000 women who provided blood samples in the Women's Health Study.
After nine years of follow-up, women with total cholesterol above 240 milligrams/deciliter had a 47 percent increased risk for ischemic stroke compared to women whose cholesterol was lower than 200 mg/dL. Stroke risk was almost twice as high for women with triglyceride levels above 200 mg/dL compared to those with levels below 150 mg/dL. Increased risk was also associated with an elevated ratio of total cholesterol: high-density lipoprotein cholesterol (HDL), or decreased HDL.
Previous studies have suggested an increased risk of ischemic stroke in men with a high total cholesterol: HDL ratio, and this study extends these findings to women. Stroke is the third leading cause of death in the United States, accounting for more than 150,000 deaths per year.
The American Academy of Neurology, an association of more than 18,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer's disease, epilepsy, Parkinson's disease, autism and multiple sclerosis.
For more information about the American Academy of Neurology, visit its website at www.aan.com/press/.
Editor's Notes: Dr. Kurth will present this research during scientific sessions at the 56th Annual Meeting at 3:45 p.m. PT (6:45 p.m. ET) on Tuesday, April 27 in Room 307 of the Moscone Convention Center. He will be available for media questions during a briefing at 3:00 p.m. PT (6:00 p.m. ET), Monday, April 26 in the on-site Press Interview Room, Room 214.