American researchers enrolled 44 patients with Alzheimer’s disease, none of whom had cardiovascular disease. Participants were randomly assigned to receive either 40 mg daily of a statin (namely, lovastatin, simvastatin or pravastatin) or 1 g daily of extended-release niacin (another cholesterol-lowering medication) for a 6-week period. All 3 statin drugs reduced levels of 24S-hydroxycholesterol by at least 20 percent, whereas extended-release niacin reduced levels by 10 percent.

"This class of drugs [statins] may be potentially beneficial in the treatment of Alzheimer's disease," said Dr. Gloria Vega, lead author of the study. "If we limit cholesterol synthesis in the brain, we may be able to decrease the production of amyloid plaques. The findings from this research provide information about the safety and efficacy of a reasonable dose of a statin on the reduction of brain cholesterol."

"We've shown that you can take people with Alzheimer's disease, with normal cholesterol levels, and reduce the amount of cholesterol that their brain produces without any adverse side effects," said Myron Weiner, MD, a study coauthor.

Unlike dietary cholesterol, which is transported to the liver and excreted through the bile, the brain eliminates cholesterol by first converting it into 24S-hydroxycholesterol, which is elevated in individuals with Alzheimer's disease. The researchers used blood samples to measure the amount of 24S-hydroxycholesterol to determine how much cholesterol was expelled from the brain.

"It would be interesting to determine whether a combination of a statin and extended-release niacin has an additive effect on levels of 24S-hydroxycholesterol," added Vega.

"Now that we've shown that statins safely and effectively reduce levels of brain cholesterol, we are studying what statins do cognitively for people with Alzheimer's," Weiner said.