Possible risk factors and precipitants for migraine with aura in discordant twin-pairs: a population-based study.

The aim of the present study was to detect possible risk factors in migraine with aura (MA) by analysis of discordant twin-pairs. In a recent population-based twin study we established that environmental factors account for approximately 50% of the variation in liability to MA. A cohort of 5,360 same-gender twin-pairs from the general population was screened for migraine. All twin-pairs with possible migraine were interviewed by a physician. A questionnaire provided information about living conditions and lifestyle. Of the 169 discordant twin-pairs 51 were monozygotic and 118 were dizygotic twin-pairs. Several putative risk factors-schooling, education, marital status, smoking status and alcohol consumption-showed no association with MA. The presence of migraine without aura or tension-type headache did not increase the risk of MA. Stress and mental tension, and bright light precipitated attacks of MA in, respectively, 44% and 28% of the twins.