The relative influence of environment and genes in episodic tension-type headache.

Objective: To examine the relative importance of genetic and environmental influence for the development of tension-type headache by analyses of twins.

Methods: The authors screened by questionnaire a population of 5,360 twins born during 1953 to 1960 from the general population for migraine and headache symptoms. The response rate of the questionnaire was 87%.

Migraine without aura and migraine with aura are distinct disorders. A population-based twin survey.

Objective: To investigate the co-occurrence of migraine without aura (MWOA) and migraine with aura (MWA) in a population-based twin survey.

Background: Migraine without aura and MWA are multifactorial disorders. If MWOA and MWA share common genes, co-occurrence should be observed more frequently than expected, ie, the product of the prevalence in the general population.