Migraine is more frequent in individuals with optimal and normal blood pressure: a population-based study.

Background: The notion that hypertension causes headache is widely accepted despite the absence of confirmation by well-designed studies.

Objective: To investigate the association between headache, characterized as tension type and migraine like, with blood pressure and hypertension.

Methods: In a cross-sectional study we evaluate this association in a sample of 1174 individuals older than 17 years, representative of inhabitants of Porto Alegre, RS, Brazil. Headache and its subtypes were defined according to International Headache Society criteria. Hypertension was defined as the mean of two blood pressure readings >or=140/90 mmHg or use of antihypertensive drugs.

Results: Headache in lifetime, in the last year, and defined as episodic and chronic tension-type headache was not associated with hypertension. Individuals with optimal or normal blood pressure (Sixth Joint National Committee criteria) complained of migraine more frequently than the participants with high-normal blood pressure or hypertension. This association persisted after adjustment for several potential confounding factors (risk ratio, 0.56; confidence interval, 0.41-0.77).

Conclusion: Our findings confirm that high blood pressure is not associated with the complaint of headache in the population. Individuals with migraine-like episodes of headache may have lower blood pressure than individuals without headache.