Common blood pressure drugs known as beta blockers may protect the brain against Alzheimer's disease and other dementias, according to new research.
"Levels of the Alzheimer lesions were about half or less in persons receiving beta blockers, compared with persons whose hypertension was untreated," said study author Dr. Lon White, a researcher at the Pacific Health Research and Education Institute in Honolulu. Beta blockers also appeared to reduce the risk of these brain changes more than other blood pressure medications did.
White added a caution, however. "It would be premature to make any specific recommendations for treatment," he said, such as suggesting people switch to beta blockers only.
Examples of beta blockers are Inderal (propranolol), Tenormin (atenolol), and Lopressor (metoprolol).
"Our findings will need to be examined in other studies before such recommendations could be made," White said.
The research does support the idea that treating high blood pressure in midlife must be part of the way to prevent late-life cognitive impairment and dementia, he said.
The study is scheduled to be presented in March at the American Academy of Neurology annual meeting in San Diego.
One in eight older American adults has Alzheimer's, a progressive brain disease, according to the Alzheimer's Association. Alzheimer's and other types of dementia affect memory, thinking, and behavior.
In the study, White and colleagues evaluated the autopsies of 774 men who were enrolled in the Honolulu-Asia Aging Study, a community-based study of Japanese-American men who were between the ages of 71 to 93 when the study began. The study was conducted from 1991 through 2012.
Of the men who were autopsied, 610 had had high blood pressure or had been treated with high blood pressure drugs. The men had taken five common types of blood pressure-lowering medicines. White also looked at two subgroups who took two or more medicines in combination, a common practice for lowering blood pressure.
After adjusting for factors such as the men's age, their blood pressure levels at the study's start, their test scores, and other factors, White found those who took beta blockers as their only blood pressure-lowering drug had fewer brain abnormalities — such as lesions associated with Alzheimer's — than those who took no hypertension drugs or other types of blood pressure medications.
Those who took beta blockers in combination with other blood pressure-lowering drugs also had fewer brain abnormalities, but the benefit was not as great as in the beta blocker-alone group.
White can't explain why the beta blockers seem to have a protective effect. "We have no way to attribute the association with fewer brain lesions to any specific underlying mechanism," he said.
An Alzheimer's expert discussed the new findings.
"This is an interesting study, and the Honolulu-Asia Aging Study has been a valuable source of information," said Heather Snyder, senior associate director of medical and scientific relations for the Alzheimer's Association.
However, she added: "It's a small study. I would agree it is premature to draw conclusions about treatment."
Some people with brain lesions, one of the markers used in the study to gauge risk of Alzheimer's, do not have cognitive changes, she added.
Until more research is in, she said, those who want to reduce their risk of Alzheimer's disease should maintain a healthy cardiovascular system by eating a good diet and staying physically active.
White will continue his research. The Alzheimer's Association has given him a grant to continue the study of the brain tissue. He will examine the tissue for signs of changes known to be linked with Alzheimer's and evaluate which risk factors during life were linked with the brain abnormalities.
Research presented at medical meetings should be viewed as preliminary until published in a peer-reviewed journal.