Abstract
The results of a community study of 1,718 individuals were used to test the hypothesis that migraine is a syndrome of headache and three features: a unilateral distribution; a warning that a headache is coming; and nausea accompanying a headache. A high proportion of individuals in the general population had experienced some of these features during the year immediately preceding the community survey. These three migrainous features were especially common among those with severe headaches. With each of these three features the prevalences increased with the severity of the headache. There was little evidence that the three features occurred in the same individual, during the twelve-month period, more frequently than would be expected on the basis of chance concurrences, depending simply on the separate prevalences of each feature. These epidemiological findings suggest the need for a more critical approach to the problems of defining migraine.