 What is the difference between dementia and Alzheimer's? Because that is one of the most common questions. And the answer is that Alzheimer's is a subset of dementia. Dementia is a broad term that just means that the person has declined cognitively enough so that it is significantly interfering with their day-to-day activities. There are many kinds of dementias. Alzheimer's is the most common type as people age. However, there are numerous others. There's vascular dementia from stroke. Very common is kind of a mix of Alzheimer's and vascular dementia pathologies in the brain. There's also less frequent types like frontotemporal dementia and Lewy body dementia and dementia is associated with Parkinson's disease. And there's kind of a long list that goes on and on.