A new study suggests that people with high blood pressure are not as likely to suffer from migraine headaches.

Researchers analyzed the blood pressure, as well as the frequency of headaches and the history of taking blood-pressure medication, of more than 51,000 Norwegians. They found that those with high blood pressure were as much as 40 per cent less likely to get headaches or migraines.

The study, to be published Tuesday in the medical journal Neurology, concludes that people with high blood pressure have stiff arteries, and it may be that they protect against migraines by affecting a part of the brain known as the baroreflex arch.

"The baroreflex arch helps maintain blood pressure, but when it is affected, it can cause hypoalgesia, a condition that makes a person less sensitive to pain," study author Dr. Erling Tronvik, of the Norwegian National Headache Centre at Trondheim University Hospital in Norway, said in a statement.

According to Tronvik, the findings support earlier studies that have linked increasing blood pressure to decreasing chronic pain throughout the body.

Migraine is a type of headache that sufferers find particularly debilitating. They often start off with an "aura" stage, where symptoms can include vision problems, numbness and dizziness. The headache itself can induce nausea, vomiting and sensitivity to light and sound, and can last from a few hours to a few days.

Migraine Canada estimates that about 3 million Canadians suffer from migraines, with women outnumbering men three to one. Sufferers alleviate their symptoms with a variety of treatments, from sequestering themselves in a dark, quiet room to sleep, to taking over-the-counter or prescription-strength pain medications.

Abstract:

High pulse pressure protects against headache

Prospective and cross-sectional data (HUNT study)

E. Tronvik, MD, L. J. Stovner, MD, PhD, K. Hagen, MD, PhD, J. Holmen, MD, PhD and J-A Zwart, MD, PhD

Background: Many antihypertensive drugs are also used as migraine prophylactics, but the relationship between blood pressure and headache is not been well understood. The objective of the present study was to explore the association between blood pressure and headache prevalence, and the effect of antihypertensive medication on this relationship, using both cross-sectional and prospective data from a large population.

Methods: We used data from two large epidemiologic studies, the Nord-Tr�ndelag Health Survey 1984-1986 (HUNT-1) and 1995-97 (HUNT-2), to evaluate the association between blood pressure (systolic, diastolic, mean arterial, and pulse pressure) and migraine and nonmigrainous headache.

Results: Increasing systolic blood pressure was associated with decreasing prevalence of having nonmigrainous headache or migraine. The most consistent and robust finding, however, was that increasing pulse pressure was linked to decreased prevalence of both nonmigrainous headache and migraine, evident for both sexes in the prospective and cross-sectional analyses. In subjects using antihypertensive medication, this finding was less clear.

Conclusion: Both increased systolic blood pressure and pulse pressure are related to arterial stiffness and may decrease headache prevalence through modulation of the baroreflex arch, which in turn generates hypoalgesia. This is due to a phenomenon called hypertension-associated hypalgesia. Stimulation of the baroreflex arch in response to increased blood pressure is assumed to inhibit pain transmission at both spinal and supraspinal levels, possibly because of an interaction of the centers modulating nociception and cardiovascular reflexes in the brainstem.

Abbreviations: BP = blood pressure; BRS = baroreflex sensitivity; DBP = diastolic blood pressure; HUNT = Nord-Tr�ndelag Health Study; ISA = intrinsic sympathomimetic activity; MAP = mean arterial pressure; NMH = nonmigrainous headache; OR = odds ratio; PP = pulse pressure; SBP = systolic blood pressure.

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