Is Alzheimer's Contagious?

Alzheimer’s disease could be caused by herpes virus, warn experts

. . .in an the editorial in the Journal of Alzheimer’s Disease, it is suggested that it is a viral or bacterial infection which triggers the plaque build-up in the first place. Targeting them specifically with antimicrobial drugs could halt dementia.

Professor Douglas Kell of the University of Manchester’s School of Chemistry, said “We are saying there is incontrovertible evidence that Alzheimer’s Disease has a dormant microbial component. We can’t keep ignoring all of the evidence.”
. . .
The authors say that viruses and bacteria are common in the brains of elderly people, and although they are usually dormant, they can ‘wake up’ after stress or if the immune system is compromised. Around two thirds of people will acquire the herpes virus at some point in their lives, and many will not realise they have it.
. . .
The herpes virus in particular is known to damage the central nervous system, and the limbic system in the brain which regulates mood and instinct and is associated with mental decline and personality changes.

They also point to the fact that a gene mutation - APOEe4 - which makes one in five people more susceptible to Alzheimer’s disease, also raises their susceptibility to infectious disease. Viral infections in the brain are already known to cause symptoms similar to Alzheimer’s and the experts say the link has been ‘neglected’ for too long.

Current attempts to find the cause, and cures for Alzheimer's aren't going that well. Following another line of research is worth the time and expense.