Bernard Sachs studied nervous system disorders in children in the United States during the nineteenth and twentieth centuries. In the late 1880s, Sachs described the fatal genetic neurological disorder called amaurotic family idiocy, later renamed Tay-Sachs disease. The disorder degrades motor skills as well as mental abilities in affected individuals. The expected lifespan of a child with Tay-Sachs is three to five years. In addition to working on Tay-Sachs disease, Sachs described other childhood neurological and developmental disorders that stem from problems with early brain development. Sachs's research in early brain development helped establish some of the physiological symptoms of hereditary neurological disorders in children, enabling doctors to diagnose the disorders earlier and to develop treatments for them.