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A prevalence study of 9000 Swedish school children conducted in 1955 showed that nearly 4% had migraine. The prevalence of migraine was 1.4% at 7 years of age and 5.3% at 15 years of age. From the age of 11 there was a gradual increase of migraine headache and a predominance among girls. A subgroup of 73 children with pronounced migraine and an average onset of 6 years was followed during a period of 40 years. The results showed that 23% of the children were migraine-free before the age of 25, boys significantly more often than girls. However, around the age of 50, more than half of the migraine group still had migraine attacks. A recall bias was found in that a number of the subjects in their middle-life (41%) could not remember that they had had aura symptoms previously. Of those who had become parents, 52% have in their present or previous families had one child or more who had developed recurrent headache, probably of the migraine-type.

The heritability of liability to self-reported migraine and nonmigrainous headaches was examined in two large cohorts from the Swedish Twin Registry consisting of 6448 (the older cohort) and 12,884 (the younger cohort) like-sexed twin pairs. Higher concordance rates were consistently found for lifetime migraine among the monozygotic twins than in the dizygotic twins, as well as for migraine headaches of the recurrent disabling type. In addition, a higher concordance rate was found among the monozygotic twins than in dizygotic twins in a "mixed" group of possible tension-type or mild migraine headaches (or both). The results of structural equation model-fitting analyses showed that genetic effects for migraine headaches were stronger for the females (estimates ranging from 49% to 58%) than for the males (39% to 44%) in the two cohorts. Unique nonshared environmental effects were greatest for the "mixed" group in both sexes (estimates ranging from 60% to 69%). The results are discussed in view of similar large-scale twin studies examining the heritability of liability to migraine.

No abstract

In 1955 a population study in Uppsala comprising about 9,000 school children showed that migraine increased from 1.4% at the age of seven to 5.3% at fifteen. With increasing age there was an increasing predominance of girls. A matched comparison between 73 children with more pronounced migraine and 73 control children showed a greater tendency in the migraine group to abdominal pain, motion sickness, sleep disturbance and orthostatic symptoms. In a longitudinal study lasting 23 years the 73 migraine children were followed-up until all were over 30 years of age. During puberty and as young adults 62% were free from migraine for at least two years. Of these, 22% again suffered migraine regularly. Thus, 60% had migraine attacks at 30. Girls seem to have a greater relapse rate than boys. Most of the girls with classical migraine were headache free during pregnancy. Every third family with one parent belonging to the migraine group and with children over four years of age had one child with migraine symptoms. Migraine seems to be more frequently inherited via the mother, and to girls.