In a study that included about 1,700 elderly people, those who took cholesterol-lowering statin drugs were about half as likely to develop dementia over five years of follow-up as those who did not.
The findings do not prove that statins protect against age-related mental decline, but they are compelling enough to justify primary prevention studies that might prove the association, researchers say.
"We aren't suggesting that people should take statins to prevent cognitive decline if they don't need them for other reasons," study author Mary N. Haan, DrPH, of the University of Michigan School of Public Health, tells WebMD. "But we need a trial designed to determine if statins really do reduce the risk of dementia and Alzheimer's disease."
Statins and Memory
Haan's study is not the first to suggest that statins protect older people against memory loss and other types of mental decline, but it is one of the first to follow patients who began the study with no evidence of such decline.
The trial included Mexican-Americans living in Sacramento, Calif., who were participants in a larger, ongoing study examining whether risk factors for heart disease affect the development of age-related memory and thinking problems.
None of the participants chosen for the analysis had been diagnosed with dementia or Alzheimer's disease at enrollment.
Of the 1,674 participants, 27% (452) took statins at any time during the study. Over five years of observation, 130 developed either dementia or cognitive impairment without dementia.
After adjusting for known risk factors for age-related mental decline, such as education level, smoking status, and history of stroke or diabetes, the researchers found that study participants that had used statins were about half as likely to show evidence of cognitive decline.
The study appears in the August issue of the journal Neurology.
Statins Lower LDL
Statins help protect against heart attacks and strokes by lowering low-density lipoprotein (LDL), or "bad" cholesterol. But Haan says this action alone does not appear to fully explain her team's findings.
"There may be something else going on here," she says.
About 100 people enrolled in the study showed evidence of dementia or cognitive impairment during their first mental evaluation, but none had been previously diagnosed.
"Most of these people lived in urban settings and had Medicare and primary care doctors, but they were not being screened for cognitive declines," she says.
Memory Problems and 'Foggy' Thinking
Ironically, much of the recent press about statins and the brain has focused on claims that the drugs cause memory problems and 'foggy' thinking in some users.
But neurologist John Hart, MD, who is medical director of the Center for Brain Health at the University of Texas at Dallas, says the claims have been largely anecdotal.
"Most of the evidence seems to suggest that statins are helpful in the long run for preventing memory loss with aging and dementia," he tells WebMD.
He agrees that a primary prevention trial is needed.
"We really need to settle this issue," he says. "There are a lot of hints that statins slow age-related memory decline. If this is the case we need to know it."