Dementia – Dementia refers to the loss of intellectual functions such as thinking, remembering and reasoning to the extent that a person's daily functioning is affected. It is not a disease in itself, but rather a group of symptoms which may accompany certain diseases or physical conditions. The cause and rate of progression of dementia vary. Some of the well-known diseases that produce it include Alzheimer's Disease, Multi-infarct Dementia, Huntington's Disease, Pick's Disease, Creutzfeldt-Jakob Disease, and Parkinson's Disease.