Study: Later retirement may help prevent dementia

June Springer, poses for a photograph, where she works at Caffi Contracting Services, Friday, July 12, 2013 in Alexandria, Va. Springer who just turned 90, works as a receptionist. People who delay retirement have less risk of developing Alzheimer's disease or other types of dementia, a study of half a million people in France found. (AP Photo/Alex Brandon)BOSTON (AP) — New research boosts the "use it or lose it" theory about brainpower and staying mentally sharp. People who delay retirement have less risk of developing Alzheimer's disease or other types of dementia, a study of nearly half a million people in France found.