Susan Levine has a story in the Washington Post Thursday about early-onset Alzheimer's, link here, along with video. Here it's called a "family disease", as was demonstrated in the recent film "Still Alice", reviewed on the Movies blog Jan. 17.
The symptoms seem innocuous at first but sometimes progress rapidly. The story relates a teenage boy in Oklahoma becoming a caregiver to his mother at only 44. Then when the boy became a man, he would develop the disease himself.
The problems for family caregivers, often much younger than with more common eldercare, are enormous.