How a medical mystery in Guam led to a new approach to Alzheimer’s disease

As part of his reporting for “The Last Alzheimer’s Patient” documentary, CNN Chief Medical Correspondent Dr. Sanjay Gupta travels to Jackson Hole, Wyoming, to learn more about an ethnobotanist’s audacious theory on treating Alzheimer’s disease. After Dr. Paul Cox, founder of the nonprofit Brain Chemistry Labs, discovered the source of a mysterious neurodegenerative disease afflicting people in Guam, those clues led him to a novel way of thinking about Alzheimer’s and a simple amino acid called L-serine. Editor's note: "Dr. Sanjay Gupta Reports: The Last Alzheimer’s Patient” airs at 8 p.m. ET Sunday, July 7, on CNN.