EPIDEMIOLOGY OF HEADACHE

This thesis is based on nine previously published papers. It represent s the first prevalence study of specific headache entities in a repres entative general population, where the diagnoses are based on a struct ured interview and examination by a physician using internationally ac cepted operational diagnostic criteria. The study population was a ran dom sample of 1000 men and women aged 25-64. The participation rate wa s 76%. The prevalences of the different forms of headache are assessed and the study provides descriptive data concerning symptomatology, pr ecipitating factors, impact of female hormones, use of medical service s and work consequences of the headache disorders and describes variou s factors associated with the disorders. Only half of migraineurs and one-sixth of subjects with tension-type headache consulted their gener al practitioner because of headache and even less consulted a speciali st. These consultation rates reflect the selection of cases that may b ias studies in clinic populations. The study supports the notion that migraine and tension-type headache are separate clinical entities and that migraine without aura and migraine with aura are distinct subform s of migraine. Migraine and tension-type headache are sex- and age-dep endent disorders with female preponderance and lower prevalence in old er age groups. The female preponderance may be explained by clinical f actors related to female hormones. There is no clear evidence of any a ssociation between sociodemographic variables and migraine or tension- type headache. Tension-type headache is related to a series of psychos ocial variables while migraine is not. The results suggest that migrai ne is primarily a constitutional disorder and tension-type headache a more complex phenomenon influenced by several psychosocial factors. Th e limitations of cross-sectional data in pointing out risk factors wit h sufficient certainty are stressed. Longitudinal follow-up studies ar e the most important challenge in Future epidemiological headache rese arch.