Blood-Pressure Drugs May Lower Alzheimer's Risk
Diuretics might have the largest effect, researchers report
MONDAY, Mar. 13, 2006 (HealthDay News) -- Taking medications to lower blood pressure, particularly diuretics, may help reduce risks for Alzheimer's disease, a new study suggests.
Experts speculate that high blood pressure may increase the risk of the brain-wasting disease. That means drugs that ease hypertension -- another name for high blood pressure -- might also lower Alzheimer's risk.
In fact, "we found that among people taking anti-hypertensives, there was an overall 40 percent reduction in the risk of developing Alzheimer's disease over a three- to four-year period," said study co-author Peter P. Zandi, an assistant professor at Johns Hopkins University's Bloomberg School of Public Health.
Drugs that lower blood pressure include diuretics, beta blockers and calcium channel blockers. While diuretics appeared to offer the greatest benefit to study participants, "we also found some evidence that there was a reduced risk with the use of calcium channel blockers," Zandi added.
His team published its report in the March 13 online edition of the Archives of Neurology.
In their study, Zandi and his colleagues collected data from 1995 to 1998 on nearly 3,300 elderly people living in Cache County, Utah. Among the people in the study, more than 1,500 used blood pressure medications. By 1998, 104 people had developed Alzheimer's disease.
The researchers found that people who were taking blood pressure medications at the start of the study were significantly less likely to develop Alzheimer's disease compared with those who were not.
The biggest effect was seen with the use of potassium-sparing diuretics -- drugs that contain additional components to maintain blood levels of potassium. These drugs were associated with more than a 70 percent reduction in the risk of developing Alzheimer's disease, Zandi's team found.
Calcium channel blockers reduced the risk by up to 50 percent, but other blood pressure drugs had little effect on the development of Alzheimer's disease, Zandi said.
It's unclear why some anti-hypertensives seem to reduce Alzheimer's disease risk and others do not, Zandi said. "There may be something special about calcium channel blockers and potassium blockers, other than their effect on blood pressure," he said.
Zandi stressed that the findings need to be viewed with caution. "We don't want people to change their anti-hypertensive medications based on this one report," he said. "The study raises a hypothesis that needs to be fleshed out and explored though other studies."
One expert thinks the results of this observational study are strong enough to be pursued in clinical trials.
"This new finding has to be taken with the caveats identified by the authors -- namely that there are several possible ways the association with reduced Alzheimer's risk they observed may not reflect real protection against Alzheimer's disease," said Greg M. Cole, a neuroscientist at the Greater Los Angeles VA Healthcare System and the associate director of the Alzheimer's Disease Research Center at UCLA's David Geffen School of Medicine.
Like other risk factors for cardiovascular disease, increased blood pressure has been consistently associated with increased Alzheimer's disease, Cole said.
"Although clinical trials with other anti-hypertensive drugs have not shown protection against Alzheimer's, the almost 75 percent level of risk reduction for Alzheimer's associated with potassium-sparing diuretic use in this study is high enough to consider clinical trials with this specific class of diuretic," he said.
The Alzheimer's Association estimates that the number of Americans diagnosed with the disease will rise from about 4 million today to over 16 million by mid-century.
With that in mind, Cole said that, "even if it means spending more money on research, we need to hurry up and identify and test safe ways to prevent Alzheimer's before the 70 million aging baby boomers bankrupt our health-care system."
For more on Alzheimer's disease, head to the Alzheimer's Association.