Frontotemporal degeneration is a group of disorders that also have a distinctive appearance, says Dr. Walter Koroshetz, director of the National Institute of Neurological Disorders and Stroke, which organized the dementia summit. "Those folks can oftentimes be seen as peculiar but not demented," Koroshetz says. "But they can be severely impaired." For example, people with frontotemporal dementia may begin to behave inappropriately or make poor decisions or become insensitive to others.