![A young woman undergoes a brain scan.](https://fortune.com/img-assets/wp-content/uploads/2025/02/20250122_Primary_0161_forweb-1536x1024-1.jpg?w=1440&q=75)
Hannah Richardson, 24, undergoes a brain scan as part of the Primary Prevention Trial for Alzheimer’s disease led by Washington University School of Medicine in St. Louis. Richardson comes from a family with a history of early-onset Alzheimer’s.
Matt Miller/WashU