No link seen between headache, high blood pressure

By Jacqueline Stenson

NEW YORK, Mar 25 (Reuters Health) - Though some studies have suggested that headaches are more common among people with high blood pressure while other research has found no connection, a new report concludes that headaches may actually be less common in those with hypertension.

Study author Dr. Knut Hagen of the Norwegian University of Science and Technology in Trondheim, Norway, told Reuters Health that high blood pressure may cause an effect called hypertension-associated hypalgesia, meaning that individuals with hypertension have a higher pain threshold and thus fewer headaches.

In the study, Hagen and colleagues found that people with a systolic blood pressure---the upper number in a blood-pressure reading--of 150 millimeters of mercury (mm Hg) or higher were 30% less likely to develop headaches than those with readings below 140.

Similarly, as diastolic blood pressure, the lower number in a blood pressure reading, increased, the risk of headache decreased, according to findings published in the April issue of the Journal of Neurology, Neurosurgery and Psychiatry.

"We expected an opposite tendency," Hagen said.

A blood pressure reading under 130/85 mm Hg is normal, according to the American Heart Association.

The study's findings held true even when the researchers took into account those participants who were taking medication for their hypertension.

However, when the study authors looked at specific types of headache, they found no clear association between hypertension and migraines.

The study involved 22,685 adults who had their blood pressure measured between 1984 and 1986. All participants were assumed to be headache-free at baseline because they said they did not use pain relievers in the prior month, however they were not actually asked whether they suffered from headaches.

In the second phase of the study, from 1995 to 1997, participants were asked about any headaches experienced in the prior year. Results showed that 28% of participants reported headaches, one fourth of them migraines.

SOURCE: Journal of Neurology, Neurosurgery and Psychiatry 2002;72:463-466.