Head-HUNT : the epidemiology of headache in Nord-Trøndelag

Headache is a general health problem that couses individual suffering as well as public expense. Research may inncrease the knowledge about headache mechanisms and improve the strategies for headache treatment. This thesis deals with the accuracy of questionnaire-based headache diagnoses, headache prevalence, and headache associations. All studies are based on data from The Nord-Trondelag Health Studies (HUNT-1 and HUNT-2), the largest medical surveys ever performed in Norway. A total of 51,383 individuals responded to a headache questionnaire in HUNT-2, and these constituted the "head-HUNT" study.The accuracy of the questionaire-based headache diagnoses was evaluated by comparing them to diagnosis made in a clinical interview ("gold-standard"). The agreement for migraine diagnosis was acceptable, and the headache sufferers were divided into two haedache types; migraine and non-migrainous headache. In addition, headache sufferers were also grouped according to headache frequency.We found that nearly four in ten individuals in Nord-Trondelag County had suffered from headache during the last year. The 1-year prevalence of migraine was evaluated sccording to a modified version of the migraine criteria of the International Headache Society, and overall more than one in ten had suffered from migraine. For frequent (>6 days per month) and for chronic headache (>14 days per month), the 1-year prevalence was 8% and 2%, respectively. Headache was more frequent among womwn in all age groups, and the prevalence peaked in the fourth decade of life.High prevalence of headache aomong patients with hypothyroidism has been found in clinical-based studies. In contrast to prior knowledge, we found low headache prevalence among women with high thyroid-stimulating hormone (TSH) values. There is no obvious explanation, but possibly, high TSH may prevent headache becouse hypothyroid subjects are less sensitive to β-adrenergic stimulation.Low socio-economic status (SES) defined by education level or occupation was associated with increased risk of frequent headache. Our reslults indicated that other factors associated with low SES, such as stress, poor diet or poor medical care may influenced headache risk (the social causal model).Previous studies exploring the relation between blood pressure and headache have shown conflicting results. In the first prospective study we found that high blood pressure was associated with reduced risk of non-migrainous headache. One possible explanation may be the phenomenom of "hypertension-associated hypalgesia".The thesis confirmed that migraine and other headaches are common complaints, especially among younger women. Pointing out headache assciations and risk factors for headache may generate new hypothesis about the pathogenesis of headache, and consequently, better headache treatment. The attendance rate in Head-HUNT was high, and hopefully, this thesis is followed by further prospective studies of the population in Nord-Trondelag.