Dementia is not a disease itself but group of symptoms that characterize diseases and conditions. Dementia is commonly defined as a decline in intellectual functioning that is severe enough to interfere with the ability to perform routine activities.

The second most common form of dementia is multi-infarct dementia caused by vascular disease and strokes.

• Other neurological diseases that can cause dementia include:
• Huntington's disease
• Parkinson's disease
• Pick's disease
• Creutzfeldt-Jakob disease