According to The National Institute on Aging, Dementia is a brain disorder that affects how people communicate and go about their daily tasks. Alzheimer's on the other hand is a disease, a form of Dementia that impacts certain regions of the brain that control thought, memories and language. "Dementia is an umbrella term, and Alzheimer's is a type of that," says neurologist Dr. Daniel Potts. Source: Alzheimer's 'New Hope for a Cure'