False Promises on Alzheimer's
In a headline-grabbing study in 2000, researchers showed that Alzheimer's disease was 70% less common in those who took cholesterol-lowering statin drugs than in those not on the drugs. But hope faded after actual clinical trials showed no benefits from the drugs. Subsequent analyses came to the same conclusion. "There is good evidence that statins do not prevent Alzheimer's," says Dr. James Wright at the University of British Columbia.
Scientists speculate that the false promise came, in part, from a familiar pitfall called selection bias. The original study compared Alzheimer's patients with healthy subjects. For reasons that aren't entirely clear, there is a strong overlap of people who are less likely to develop Alzheimer's and people who are concerned about their health, and therefore inclined to take statins.