High blood pressure linked to fewer headaches

High blood pressure linked to fewer headaches

Researchers in Norway have shown that high blood pressure is linked to fewer headaches, possibly due to having stiffer artery walls which affects a homeostatic process that regulates blood pressure and decreases sensitivity to pain.

The study is the work of Dr Erling Tronvik, a neurologist with the Norwegian National Headache Center, Trondheim University Hospital, in Trondheim, Norway, and colleagues, and is published in the early online 15th April issue of the journal Neurology.

Many blood pressure drugs are also used to treat migraine, said the researchers in the background to the article, but the link between blood pressure and headache remains somewhat unclear.

The reason for the study was to explore the link between blood pressure and headache frequency, and how blood pressure medication affects that relationship. To do this the researchers used both cross-sectional and prospective data from two large epidemiologic studies covering 51,353 men and women over the age of 20 living in Norway.

The two large studies were called HUNT1 (Nord-Trøndelag Health Survey 1984-1986) and HUNT2 (Nord-Trøndelag Health Survey 1995-1997), from which the researchers looked at the association between migraine and nonmigrainous headache and various measures of blood pressure: systolic, diastolic, mean arterial, and pulse pressure.

Systolic blood pressure is when the heart contracts (the higher measure), diastolic is when the heart relaxes (the lower measure), mean arterial pressure is the average of diastolic and systolic, and pulse pressure is systolic minus diastolic (the change in pressure when the heart contracts).

The results showed that:

  • Increasing systolic pressure was linked with decreasing prevalence of migraine and nonmigrainous headache (people with higher systolic blood pressure were up to 40 per cent less likely to have headaches).
  • The most robust and consistent association was the link between increasing pulse pressure and decreasing prevalence of both migraine and nonmigrainous headache.
  • This link was present for both men and women, in both studies.
  • The finding was less clear in cases where people were also taking blood pressure medication.
The researchers concluded that both increased systolic and pulse pressure are linked to stiffness in the arteries and this may explain the decrease in headaches because of a phenomenon called "hypertension-associated hypalgesia" (blood pressure linked reduction in pain sensitivity).

When the baroreflex arch (a homeostatic process that helps to maintain blood pressure) is stimulated by high blood pressure, it inhibits pain at "both spinal and supraspinal levels, possibly because of an interaction of the centers modulating nociception and cardiovascular reflexes in the brainstem", wrote the researchers.

Tronvik said in a prepared statement that these results confirmed previous studies that showed increasing blood pressure was linked to decreasing amounts of chronic pain in all parts of the body.

"High pulse pressure protects against headache: Prospective and cross-sectional data (HUNT study)."

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

Neurology, Apr 2008; 70: 1329 - 1336.

Click here for Abstract.

Source: Journal article, press release from American Academy of Neurology.

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