Incurable and increasingly prevalent, dementia is a disease that today affects about 50 million people worldwide. Millions more are diagnosed each year with the most common neurodegenerative form: Alzheimer’s disease. The risks generally increase with age, but many people develop symptoms of dementia before they reach the age of 65. Inheritable genetic conditions can lead to familial or early-onset Alzheimer’s, which can afflict people as young as 30. Despite growing ...