Editor’s note: CNN Chief Medical Correspondent Dr. Sanjay Gupta and writer Sandee LaMotte are part of the study covered in this story and have written about their experiences. When Penny Ashford’s ...

(CNN) — When Penny Ashford’s father was diagnosed with early-stage Alzheimer’s disease at age 62, she knew the devastating brain disorder might one day steal her memory. In her late 50s, her ...