Many studies have found stroke as a risk factor for migraines, but a recent study from Brain has argued the opposite.
Migraines, complex headache disorders, are known to affect 11% of the population and females predominantly at a ratio of 3:1. (From paper) Importantly, migraines are a common recurring disorder that plague a significant part of the population, which make it an accessible biomarker for classifying disease risk. Consequently, the published study is an important one, for it gives us a sense of feel for how important migraines are to predicting strokes.
Stroke, a likewise complex disorder, is characterized by either blockage or bursting of a cerebral artery and normally leads to physical or mental impairment. As simple as it sounds, there are many factors that contribute to risk of stroke. However, according to this paper, migraine is probably not one of them. To many physicians, this finding is not intuitive and this recent study runs countercurrent to the prevailing idea that migraines are a key contributor to stroke.
The paper used the International Classification of Headache Disorders on a cohort of Swedish twins (both monozygotic and dizygotic) to generate their data. They also compared migraines with aura vs. migraines without. Auras are feelings that precede the migraine. You can think of them kind of like the silence that precedes a thunderstorm.
Ultimately, their results showed that there was not much of an association between migraines without aura and risk of stroke. However, for migraines with aura, they found 27% increased chance of stroke which was consistent with previous studies. Even then, a small cohort of patients were analyzed by within-pair analyses (which I think would control for more factors maybe?) and the correlation of risk was attenuated.
Overall, I thought this paper was quite interesting, as we don’t normally consider degrees of risk when we think about risk factors for disease. I don’t believe that people inherently have a gift for juggling percentages, which makes studies like these all the more interesting for picking away at the nuances of common killers like stroke. I really appreciate the study done on such a common disease and look forward to reading papers like these that are relatively “more understandable” to get a better idea of brain pathology in the near future.
- Maria Lantz, Johanna Sieurin, Arvid Sjölander, Elisabet Waldenlind, Christina Sjöstrand, Karin Wirdefeldt; Migraine and risk of stroke: a national population-based twin study, Brain, Volume 140, Issue 10, 1 October 2017, Pages 2653–2662, https://doi.org/10.1093/brain/awx223