Cholesterol-lowering drugs called statins were thought to reduce the risk of Alzheimer’s, but a major new study has found no Alzheimer’s benefits to the drugs.

“Physicians should not prescribe them for Alzheimer’s disease,” said Dr. Zoe Arvanitakis, a neurologist at Rush University Medical Center, lead author of the study.

Cholesterol appears to play a role in the development of Alzheimer’s, so researchers thought that lowering cholesterol might be an effective way to fight the disease. Researchers also thought that statins might fight Alzheimer’s by reducing inflammation in the body.

The researchers followed 929 people from around the United States, average age 75, who did not have any form of dementia at the beginning of the study.

The participants underwent cognitive and neurological tests every year for up to 12 years and consented to having a brain autopsy after their death. The researchers used 19 tests to measure their global cognition. There were seven tests for episodic memory, four tests for semantic memory, four tests for working memory, two tests for perceptual speed and two tests for visuospatial ability.

A number of 119 of the participants were taking a statin drug. Over the course of the study, 191 people developed Alzheimer’s disease, the researchers discovered. The researchers also performed brain autopsies on more than 250 people who died during the study. They found no evidence that taking statins had an effect on pathology of Alzheimer’s disease or strokes.

“We did not find that statins were associated with a lower risk of Alzheimer’s disease, with less decline in thinking ability or with Alzheimer’s disease changes in the brain at time of death,” said Arvanitakis in a telephone interview.

The researchers also found that statins did not prevent memory loss either.

“The area is topical and we know that several studies have repeatedly suggested that Alzheimer’s disease may be less likely in persons taking statins,” said Arvanitakis.

Alzheimer’s disease, a brain disorder that ruins one’s ability to carry out daily activities, usually begins after age 60. It is the most common form of dementia among the elderly.

However, the results of the study are not conclusive. The researchers are expecting results from other clinical trials, which should provide a definite answer on the issue. “We will see the results of these trials fairly soon,” said William Thies, vice president of medical and scientific affairs for the Alzheimer’s Association.

The study, supported by grants from the National Institute on Aging, was published in the January 16 online edition of Neurology.