One day in 1999 former NASA astronaut Duane Graveline, then 68 years old, returned home from his morning walk in Merritt Island, Fla., and could not remember where he was. His wife stepped outside, and he greeted her as a stranger. When Graveline's memory returned some six hours later in the hospital, he racked his brain to figure out what might have caused this terrifying bout of amnesia. Only one thing came readily to mind: he had recently started taking the statin drug Lipitor.