Alzheimer's disease has long remained a deadly mystery.
But scientists say they've now pinpointed a rare piece of DNA that may shield against the illness -- even in people who are otherwise at high risk.
The discovery may explain why some people with known genetic risk factors don't develop Alzheimer's, the study authors said.
And it could lead to new ways to fight the memory-robbing disease. For example, this genetic function could potentially be targeted with drugs to help lower people's odds of developing Alzheimer's.