Cholesterol-lowering statins, a popular class of drugs that includes Pfizer Inc.‘s Lipitor, may slow the progression of Alzheimer’s disease, according to results from a small study presented on Tuesday.

In the study, patients taking Lipitor in addition to standard therapy for Alzheimer’s were more likely to remain stable, while most of those on a placebo suffered a deterioration in brain function and a worsening of depression. The study, which included 46 patients, was presented at the American Heart Association’s annual meeting in New Orleans.

Alzheimer’s disease is a progressive and irreversible deterioration in memory, believed to be caused by a build-up of toxic plaque in the brain. Victims tend to have excess cholesterol build-up in the brain, promoting the production of toxins.

Patients in the study had mild to moderate Alzheimer’s, averaged 78 years old and were tracked for a year. They took the statin or placebo in addition to the conventional therapy for Alzheimer’s, drugs called cholinesterase inhibitors.

“At a minimum we’ve delayed their entrance into a nursing home,” said Larry Sparks, senior scientist at the Roberts Laboratory for Neurodegenerative Disease Research in Arizona, and a lead study author. “This may prove that two drugs work better than one alone.”

Fifty-three percent of those on Lipitor improved or stabilized, compared to 28 percent of those on the placebo.

Scores on a cognitive test on average remained stable for those on Lipitor, versus a decline among those getting the placebo.

Pfizer is among those now conducting larger human trials to further test the hypothesis that reducing cholesterol can stall the progression of Alzheimer’s, Sparks said.

Statins are taken by an estimated 13 million Americans and include AstraZeneca Plc’s Crestor and Merck & Co.‘s Zocor, in addition to Lipitor.