April 14, 2008 -- Having high blood pressure was associated with a reduced risk for migraines in a new study, but the preliminary findings don't prove that high blood pressure is protective, researchers say.
Participants in a Norwegian population study who had higher-than-normal systolic blood pressure reported up to 40% fewer headaches or migraines than people with lower blood pressure.
The finding was somewhat surprising, given that beta-blockers and other blood pressure-lowering drugs are often prescribed to prevent migraines.
"This is a paradox," lead researcher Erling Tronvik, MD, tells WebMD. "Several earlier studies have linked increasing blood pressure to a decrease in chronic pain in general, and this study suggests that the same is true for migraines."
Blood Pressure-Migraine Connection
It was long assumed that migraines and other types of headaches are more common among people with high blood pressure, but studies conducted in the 1990s did not support this belief.
Researchers from the Norwegian National Headache Center first reported a possible link between high blood pressure and protection against headaches in a study published in 2002.
In an expansion of that research, the researchers recently reviewed data from two large-population health studies and published their findings in the April 15 issue of the journal Neurology.
The data included information on blood pressure, use of blood pressure medications, and headache frequency for 51,353 adults living in Norway in the 1980s and 1990s.
Higher systolic blood pressure was associated with a decreased prevalence of migraines and other headaches, but the association was weak among people who took drugs that lower blood pressure.
A Possible Cause
The researchers conclude that the most likely explanation for their finding is that high blood pressure causes a decreased sensitivity to pain through a key blood pressure-regulating mechanism known as the baroreflex.
"Both animal and human studies suggest that stimulation of the baroreflex arch can inhibit pain transmission," Tronvik says. "So changes in blood pressure may affect headache and migraine."
This doesn't mean that migraine sufferers or people who have frequent non-migraine headaches should ignore their high blood pressure, particularly because blood pressure-lowering medications are known to help prevent migraines, the researchers conclude.
Mayo Clinic professor of medicine Gerald Fletcher, MD, who is a spokesman for the American Heart Association, agrees.
"People should not take this as a reason to abandon their hypertension medications," he tells WebMD. "High blood pressure is a huge problem in this country, and far too few people are controlling it as they should."