Delirium is very common on COVID wards. Researchers are testing whether these temporary bouts of confusion could bring on permanent cognitive decline. In her job as a physician at the Boston Medical Center in Massachusetts, Sondra Crosby treated some of the first people in her region to get COVID-19. So when she began feeling sick in April, Crosby wasn’t surprised to learn that she, too, had been infected. At first, her symptoms felt like those of a bad cold, but by the next