October 22, 2007
Can cholesterol-lowering statin drugs, commonly prescribed for those at risk for heart disease and stroke, also lower the risk of Alzheimer's disease? That's the tantalizing proposition held forth by ongoing research into the causes and prevention of a disease that afflicts more than five million Americans. Population studies on the potential benefits of statin drugs have shown mixed results when it comes to preserving memory and thinking skills. But a preliminary new study suggests that popular cholesterol-lowering medicines like Zocor, Mevacor, and Altocor, taken by millions, may have benefits for the brain.
Researchers from Group Health, the University of Washington, and the Veterans Affairs Puget Sound Health Care System in Seattle found that seniors in their 60s and 70s who were taking statin drugs before they died had fewer of the twisted tangles commonly found in the brains of those with Alzheimer's disease. This is the first time the microscopic effects of cholesterol-lowering medications on the brain have been examined on autopsy, the researchers note.
Of the 110 men and women in the study, about a third were taking statin drugs for an average of five years before death. Although the investigators did not find differences in terms of who was showing signs of memory loss and Alzheimer's, those who were taking the medicines were discovered to have fewer neurofibrillary tangles in the brain after death.
Tangles, the rope-like bundles that form inside the brain cells of those with Alzheimer's, are a hallmark of the disease. People with Alzheimer's are also afflicted with brain plaques, formed from the toxic buildup of the protein beta-amyloid. Although statin drugs seemed to lead to fewer tangles, they did not seem to have an effect on the number of beta-amyloid plaques, the researchers reported.
Doctors are unsure why cholesterol drugs might benefit those with Alzheimer's disease. Some earlier research suggests that statins may lead to lower levels of beta-amyloid, although that effect was not apparent in this study. High cholesterol can also promote inflammation and narrow arteries and blood vessels, including those that nourish brain cells essential for thinking and memory.
Some earlier studies also suggest that medicines that lower cholesterol may help to slow the relentless downward progression of those with Alzheimer's disease. [See the story, "Cholesterol Drugs May Slow Alzheimer's Progression."] However, other studies have shown that drugs have little effect on keeping the memory sharp. [See the story, "Cholesterol-Lowering Drugs of Uncertain Benefit for Alzheimer's."]
More research must be done to untangle the effects of cholesterol drugs on the brain. Currently, doctors do not know enough to recommend statins for the routine prevention or treatment of Alzheimer's disease, although such drugs have proven benefit for the heart.
The Fisher Center for Alzheimer's Research Foundation continues to fund vital research into the underlying causes of Alzheimer's disease, opening the way to new avenues of treatment and prevention. To learn more, visit www.ALZinfo.org, the Alzheimer's Information Site.
Li, G. Neurology, August 28, 2007; vol 69: pp 878-885.