DefinitionDementia is a loss of brain function that occurs with certain diseases. It affects memory, thinking, language, judgment, and behavior.See also: Alzheimer's diseaseAlternative NamesChronic brain syndrome; Lewy body dementia; DLB; Vascular dementia; Mild cognitive impairment; MCICauses, incidence, and risk factorsMost types of dementia are nonreversible (degenerative). Nonreversible means the changes in the brain that are causing the dementia cannot be stopped or turned back. Alzheimer's disease is the most common type of dementia.Lewy body disease is a leading cause of dementia in elderly adults. People with this condition have abnormal protein structures in certain areas of the brain.Dementia also can be due to many small strokes. This is called vascular dementia.The following me