What is the second most common cause of dementia?

In a lecture delivered at the 2008 American Academy of Neurology meeting, Dr. Helena C. Chui, chair of neurology at UCLA, posed the following question: What is the second most common cause of dementia after Alzheimer disease? Her answer was that if you are talking about a primary neurodegenerative disease, it’s Dementia with Lewy Bodies. If, however, you are talking about any kind of dementia, vascular dementia takes the number two spot. The problem from the neuropathologist’s point of view is that it is difficult to arrive at criteria for the diagnosis of vascular dementia. Do four infarcts give you vascular dementia? Seven? It depends, of course, upon where those infarcts are located. Theoretically, a single infarct in the thalamus can result in dementia. All the neuropathologist can really do is list the locations and sizes of the infarcts identified at autopsy and let the neurologist make the call as to whether or not the patient’s dementia is due to a vascular cause.