Overall, the risk of a stroke is 78 per cent higher in women who have migraines. The chances of an ischaemic stroke - one caused by a blockage of a blood vessel in the brain - are three and a half times higher in women who have migraines; and if they use a high-dose contraceptive pill and smoke, it is over 34 times higher. There was also an increased risk in women with high blood pressure.
Stroke is relatively uncommon in women under 45, but scientists from Imperial College School of Medicine and the Radcliffe Infirmary in Oxford say the size of the increased risk is "worrisome". The risks of a haemorrhage stroke, one caused by a burst blood vessel in the brain, were unaffected by a history of migraine.
Dr Limmie Chang, of the cardiovascular studies unit at Imperial College, who led the research published in the British Medical Journal, wrote: "The data presented here suggest that women who have migraine should be advised strongly not to smoke and that their blood pressure should be carefully monitored and controlled."
The study, conducted in five European countries, examined 291 women aged 20 to 44 who had suffered a stroke. One- quarter had a history of migraine and a further quarter had a family history of the condition, a factor that also increased the risk of a stroke, although they were not personally affected.
The researchers found that up to 40 per cent of the strokes developed from a migraine attack. More than two-thirds of women with a history of migraine said they had had a headache in the three days before the stroke, compared with one-quarter of those with no history of migraine. However, in some, the headache stopped before the symptoms of ischaemic stroke appeared.
Smoking and the contraceptive pill are both known to increase the risk of blood clots forming which, if they become lodged in the small arteries supplying blood to the brain, can cause a stroke. For women taking the contraceptive pill, a change in the type or frequency of migraine associated with it appeared to make no difference to the risk.Reuse content