Your Brain on Statins

The cholesterol-lowering drugs known as statins, taken by more than 15 million Americans, have proven to be a powerful weapon in the battle against heart disease. Now, new research indicates that statins may benefit the brain as well. A study appearing Monday in the journal Neurology found that statins dramatically reduced the risk of developing dementia and Alzheimer's disease among a group of subjects 60 years and older. "It suggests that if you took statins before dementia set in, you might be 50% less likely to develop the condition," says Mary Haan, an epidemiology professor at the University of Michigan and the study's lead author. "That's a really big effect."

The potential of statins to treat dementia and Alzheimer's has been the subject of investigation for years, but to date the results have been mixed. While no clear benefit has been established for the treatment of existing dementia, studies gauging the ability of statins to prevent the disease in cognitively healthy people have been slightly more promising. But exactly how statins affect cognition remains a mystery. And experts say it's one of several puzzles that must be solved before doctors and patients can harness the full potential of these drugs, which have already become a staple of the American medicine cabinet.

Haan and her colleagues followed 1,674 elderly Mexican Americans for five years, all of whom were dementia-free at the start of the study. They monitored both mental and physical health every 12 to15 months. After adjusting for factors like education, smoking status and genetic pre-disposition, statin users were found to have a 50% lower risk of developing dementia than those not taking the drugs.

But much more research will be needed before doctors routinely prescribe statins to prevent dementia. While epidemiological studies like Haan's have been generally positive, randomized clinical trials—the benchmark of clinical research—have, for the most part, failed to show any cognitive benefits. Researchers aren't sure which data to trust.

It's possible that cognitive benefits only come with years of statin use. If that's the case, clinical trials that last but a few months would not reveal such benefits. On the other hand, epidemiological studies are not randomized and those who wind up taking statins in such studies may be resistant to cognitive decline for reasons other than statin use. "It could be a false positive," says Benjamin Wolozin, a neurologist at Boston University who studies statins and cognition. "Distinguishing between these two possibilities is exceedingly difficult."

More clues may come from a prospective, double-blind, placebo-controlled clinical trial of the statin Zocor that is nearing completion. Unlike Lipitor, which was used in previous trials that did not find cognitive benefits, Zocor actually crosses the blood-brain barrier and enters the brain. "Brain permeant statins might be far more effective than statins that don't get into the brain," says Wolozin. "The reality is that many people take statins already. The key question might be which statin produces cognitive benefits?" Haan's subjects took a range of statins, including both Zocor and Lipitor.