Dementia is a broad category of brain diseases that cause long term loss of the ability to think and reason clearly that is severe enough to affect a person's daily functioning. For the diagnosis to be present it must be a change from how the person was previously.
The most common form of dementia is Alzheimer's disease. Other forms include Lewy body dementia, vascular dementia, frontotemporal dementia, progressive supranuclear palsy, corticobasal degeneration, normal pressure hydrocephalus and Creutzfeldt–Jakob disease.
Except for a few treatable types in most cases there is no cure. Cholinesterase inhibitors are often used early in the disease course; however, benefit appears to be slight. Cognitive and behavioral interventions may be appropriate. Educating and providing emotional support to the caregiver is of importance. Exercise programs are beneficial with respect to activities of daily living and potentially improving dementia.