title: Blood pressure as a risk factor for headache and migraine: a prospective population-based study.
abstract: OBJECTIVE
  During the past decade, several population-based studies have found an inverse association between blood pressure (BP) and headache. However, most of them have a cross-sectional design or lack a validated definition of a headache-free population at baseline. Therefore, additional population-based studies using a clearly defined headache-free population and a prospective design are warranted.
  
  
  METHODS
  Data from two large epidemiological studies, the Nord-Trondelag Health Survey 1995-1997 (HUNT 2) and 2006-2008 (HUNT 3), were used to evaluate the association between BP (systolic, diastolic and pulse pressure) at baseline and headache (migraine and tension type headache) at follow-up.
  
  
  RESULTS
  An inverse relationship was found between all three BP measures at baseline in HUNT 2 and any headache in HUNT 3, more evident for systolic BP [odds ratio (OR) 0.90 per 10 mmHg increase in systolic BP, 95% confidence interval (CI) 0.87-0.93, P < 0.001] and pulse pressure (OR 0.84 per 10 mmHg increase in pulse pressure, 95% CI 0.80-0.89, P < 0.001) than for diastolic BP (OR 0.92 per 10 mmHg increase in diastolic BP, 95% CI 0.87-1.00, P = 0.036). The most robust finding, evident for both sexes, was that increased pulse pressure was linked to decreased prevalence of both migraine and tension type headache.
  
  
  CONCLUSIONS
  An inverse relationship between BP and subsequent development of headache was confirmed in this large-scale population-based cohort study. Nevertheless, further research is needed to investigate the underlying mechanisms explaining these findings.
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: C F
authors.initials: CF
authors.lastname: Fagernæs
authors.forename: I
authors.initials: I
authors.lastname: Heuch
authors.forename: J-A
authors.initials: JA
authors.lastname: Zwart
authors.forename: B S
authors.initials: BS
authors.lastname: Winsvold
authors.forename: M
authors.initials: M
authors.lastname: Linde
authors.forename: K
authors.initials: K
authors.lastname: Hagen
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000453:epidemiology*; D009664:Norway / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D018781:Tension-Type Headache / Q000453:epidemiology*
keywords: blood pressure; headache; hypertension-associated hypalgesia; migraine