Lewy body dementia (LBD) is a complex and challenging brain disorder. It is complex because it affects many parts of the brain in ways that scientists are trying to understand more fully. It is challenging because its many possible symptoms make it hard to do everyday tasks that once came easily. Although less known than its "cousins" Alzheimer's disease and Parkinson's disease, LBD is not a rare disorder. More than 1 million Americans, most of them older adults, are affected by its disabling changes in the ability to think and move. As researchers seek better ways to treat LBD-and ultimately to find a cure-people with LBD and their families struggle to get an accurate diagnosis, find the best treatment, and manage at home.