Summary: A national twin study published in Brain finds a modestly increased risk of stroke for people who experience migraine with aura, but no clear increase in stroke risk for those who have migraine without aura.
Source: Karolinska Institute.
Migraine with aura is linked to a slightly higher stroke risk, while migraine without aura shows no clear association, according to a Swedish twin study with a 12-year follow-up published in the journal Brain.
Migraine affects between 11 and 13 percent of the population and is up to three times more common in women. It typically begins in adolescence or early adulthood and is characterized by recurrent headaches often accompanied by nausea, vomiting, and sensitivity to light or sound. About one in three people with migraine experience an aura—transient neurological symptoms such as visual disturbances or sensory changes—before the headache phase. For decades, research has suggested that migraine, particularly migraine with aura, may increase the risk of stroke. Other factors reported to modify that risk include female sex, younger age (under 45), smoking, and use of hormonal contraceptives.
Large twin cohort and long follow-up
The researchers used the Swedish Twin Registry and followed more than 53,000 twins for an average of nearly 12 years. In this cohort, about 16.2 percent reported some form of migraine and roughly 6.7 percent reported migraine with aura. During the follow-up period, 1,297 of the participants experienced a stroke. Stroke diagnoses were identified through national patient and cause-of-death registers and included both ischemic and hemorrhagic subtypes.
When the investigators examined the relationship between migraine and stroke, their results were broadly consistent with previous research but indicated a smaller overall risk than some earlier studies suggested. After adjusting for age and sex, the hazard ratio for stroke among people with migraine with aura was 1.27 (95% confidence interval 1.00–1.62; P = 0.05), indicating a modestly elevated risk. By contrast, the age- and sex-adjusted hazard ratio for any migraineous headache was 1.07 (95% confidence interval 0.91–1.26; P = 0.39), a result that does not show a statistically significant increased risk.
“We found no increase in stroke risk for individuals with migraine without aura, and only a modestly higher risk for those with migraine with aura, which is lower than earlier estimates,” says Maria Lantz, a postdoctoral researcher at Karolinska Institutet’s Department of Clinical Neuroscience.
Familial factors and within-pair analyses
To explore whether shared genetic or early environmental factors might influence the association, the team performed within-pair analyses of twins. These analyses reduce confounding by familial factors because twins share genes and aspects of early upbringing. The within-pair analysis attenuated the association between migraine with aura and stroke (hazard ratio 1.09; 95% confidence interval 0.81–1.46; P = 0.59), suggesting that familial influences—heredity or childhood environment—could partly account for the observed link.
The relationship between migraine with aura and stroke was also examined across subgroups. Estimates tended to be higher among women and in participants younger than 50 years, but these stratified findings were not statistically significant in this study.
Importantly, the main results remained largely unchanged after adjusting for established cardiovascular risk factors such as smoking and high blood pressure, indicating that these factors did not fully explain the modest association seen with migraine with aura.
Clinical implications
These findings refine our understanding of how migraine relates to stroke risk. For people who experience migraine without aura, the study offers reassurance that there is no clear increase in stroke risk based on this large, population-based twin sample. For those with migraine with aura, the data indicate a modestly increased risk, but smaller than previously reported and potentially influenced by familial factors. Clinicians can use these results to inform risk discussions and to consider family history and other vascular risk factors when assessing patients with migraine with aura.
Funding and publication
The study was funded by Stockholm County Council through the ALF scheme and the Swedish Migraine Society. The research, titled “Migraine and risk of stroke: a national population-based twin study,” was published online in Brain on September 26, 2017, by Maria Lantz, Johanna Sieurin, Arvid Sjölander, Elisabet Waldenlind, Christina Sjöstrand, and Karin Wirdefeldt.