There has been some evide nce that statins cause cognitive problems, and enough case reports to make the Food and Drug Administration require a warning label on the medicines. But a large Australian study reports that the cholesterol-lowering drugs are not associated with a decline in memory or thinking ability.

Over six years, researchers periodically measured mental acuity in 1,037 men and women aged 70 to 90. They used M.R.I. brain scans to calculate the brain volume of 526 of the subjects at the beginning and at two years into the study.

The rate of cognitive decline was the same in those who used statins continuously and those who never took them. Brain volume changes were the same in statin users and in those who never used the drugs. In participants with heart disease and a genetic disposition to Alzheimer’s disease, statin use was actually associated with better scores on some memory tests. The findings were published in the Journal of the American College of Cardiology.

The lead author, Dr. Katherine Samaras, a professor of medicine at the University of New South Wales, acknowledged that the study was observational, and that it may be that people who take statins are healthier to begin with.