Older adults taking blood pressure medication seem to have a reduced risk of developing Alzheimer’s disease, according to a report by Ara S. Khachaturian, Ph.D., and colleagues in the March Archives of Neurology.

The study found that one specific type of drug, potassium-sparing diuretics, appeared to have the greatest impact, reducing risk by more than 70 percent. Potassium-sparing diuretics control blood pressure by removing excess fluid from the body. Unlike other diuretics, they do not tend to wash potassium, an essential mineral, out of the body along with the excess fluid. The benefit from potassium-sparing diuretics did not seem tied to their impact on blood pressure, suggesting they may influence Alzheimer risk through a different mechanism.

“There is a growing body of evidence linking high blood pressure to an increased risk of late-life cognitive decline, and a growing awareness that it may be important to control blood pressure to protect the brain as well as the heart,” says William H. Thies, Ph.D., Alzheimer’s Association vice president, medical and scientific relations. “It isn’t yet clear why potassium-sparing diuretics in particular might be linked to a greater reduction in risk of Alzheimer’s. There is some evidence that low potassium levels are associated with inflammation, constriction of blood vessels, and other effects that could contribute to Alzheimer’s disease. As the authors note, we’ll need more studies specifically designed to test the effect of these drugs on Alzheimer’s and explain how they work if their impact is due to something other than their effect on blood pressure.”

Khachaturian and colleagues’ data is from the Cache County Study, an ongoing investigation of Alzheimer’s disease and other dementias among a large percentage of the older adults in Cache County, Utah. Information from more than 1,450 participants who were taking some form of blood pressure medication at the time the study began were analyzed for this report. Numbers of participants taking specific types of medication were considerably smaller. For example, only about 300 were taking potassium-sparing diuretics.

Khachaturian reported preliminary results of this study in July 2004 in Philadelphia at the 9th International Conference on Alzheimer’s Disease and Related Disorders (ICAD), presented by the Alzheimer’s Association.