Dementia is a blanket term that covers a large list of diseases. Alzheimer's causes dementia, but it is not the only one. Parkinson's can cause dementia, certain medical conditions (heart attack, stroke, brain injury, etc) can also cause dementia. The easy answer is that dementia is a symptom, Alzheimer's is a disease which has dementia as a symptom.
at 1:23 AM on Sep. 25, 2010