Taking medications to lower blood pressure may be associated with a lower incidence of Alzheimer's disease

Taking medications to lower blood pressure, particularly those known as diuretics, may be associated with a lower incidence of Alzheimer's disease, according to a study in the May 2006 print issue of Archives of Neurology.

Hypertension (high blood pressure) may increase the risk of Alzheimer's disease (AD), according to background information in the article. Researchers have therefore begun to examine whether antihypertensive agents, medications prescribed to treat high blood pressure, could reduce the risk of AD. These drugs include diuretics, which cause the kidneys to excrete water and salt, and beta blockers, which results in slowing the heart rate, reducing the heart's pumping action and widening blood vessels.

Ara S. Khachaturian, Ph.D., of Khachaturian and Associates, Inc., Potomac, Md., and colleagues examined the association between antihypertensive medications and the incidence of AD in 3,297 elderly residents of Cache County, Utah. Between 1995 and 1997, participants age 65 years and older were given an initial interview and assessment that included screening for dementia and a detailed inventory of all prescription and over-the-counter medications. Residents who had AD at the first interview were not included in the study. Follow-up assessments were done three years later, beginning in 1998.

Of the participants, 1,507 (944 women and 563 men) used antihypertensive medications and 1,790 (975 women, 815 men) did not. At the second assessment, 104 participants had developed AD. Elderly individuals who were using antihypertensive medications at the beginning of the study were significantly less likely to have developed AD than those who were not. This relationship persisted when the researchers controlled for other factors, including gender, age, high cholesterol, diabetes and genetic risk. When antihypertensives were broken down by type, diuretics were most strongly associated with a lower incidence of AD. More specifically, potassium-sparing diuretics, which contain additional components to preserve levels of the mineral in the body, were related to a more than 70 percent reduction in the risk of AD. Beta blockers and antihypertensives known as dihydropyridine agents also were linked to a slightly protective effect against AD, while those called ACE inhibitors did not appear to be associated with the risk of developing the condition.

Although the exact reasons for the link between potassium-sparing diuretics and reduced risk of AD is unclear, the authors suggest that the increased blood potassium levels associated with the medications may be a factor. "As yet unpublished findings  also suggest that increased potassium levels may be associated with a reduced risk of dementia," they write. "Consistent with this idea are observations that low potassium concentrations are associated with oxidative stress, inflammation, platelet aggregation and vasoconstriction, all of which are possible contributors to AD pathogenesis."

"We suggest these findings should prompt further epidemiologic and basic science studies into the possible neuroprotective effects of these drugs," they conclude.