Alzheimer’s researchers are increasingly interested in people like McCowan because “people with Down syndrome represent the world’s largest population of individuals predisposed to getting Alzheimer’s disease,” says Michael Rafii, director of the Memory Disorders Clinic at UCSD.
Down syndrome is a genetic disorder that’s best known for causing intellectual disability. But it also causes Alzheimer’s. “By the age of 40, 100 percent of all individuals with Down syndrome have the pathology of Alzheimer’s in their brain,” Rafii says.