July 28, 2020
In this image from video provided by Washington University, researcher Nicolas Barthelemy works on a p-tau217 test for Alzheimer's disease at a laboratory in St. Louis, Mo., on Monday, July 27, 2020. Several companies and universities have developed versions of these tests, which look for a form of tau protein, one of the substances that can build up and damage the brains of people with Alzheimer’s. (Huy Mach/Washington University, St. Louis via AP)