Yes, in the past this has been true. Also, the chemical world is incredibly complex and we have trouble modeling single chemical interactions with the human body let alone multiple. As I mentioned we are seeing latent viruses as the cause of other neurological syndromes like Multiple Sclerosis (from mono) and Parkinson's (from pegavirus).

The truth is it may be several factors that are exacerbating the ability of these viruses to cause damage and we are still not able to put the pieces of the puzzle together. Part of this is grouping many different possible causes under a single syndrome like we see with genetic Alzheimer's and environmentally related/viral Alzheimer's.

I have had the displeasure of working with Alzheimer's for over a decade. It truly is a horrible disease that steals your loved ones away before you eyes.