Dementia is a general decline in a person's mental abilities that is severe enough to interfere with daily living and activities. It affects memory, problem solving, learning, and other mental functions.
A variety of conditions can cause dementia, including injuries to the brain from tumors, head injury, or stroke; diseases, such as Alzheimer's disease; or long-term alcohol dependence. People (especially older adults) who are depressed may seem to have dementia when they do not (pseudodementia).
People who have dementia often experience:
WebMD Medical Reference from Healthwise