[hobo123]

I wonder if infections do not cause more dementia, but are simply correlated with more. A weaker immune system may trigger many many things.

And similar questions about obesity "causing" many diseases, sunburns causing skin cancer (although that sounds somewhat plausible) etc.

[tptacek]

There isn't a causal mechanistic link between shingles and Alzheimers. We don't know why the Shingrix vaccine reduces incidence of Alzheimers.

(You should very much want to avoid any chance of getting shingles, though; it's a nightmare.)

[DANmode]

Probably other, possibly even unknown viruses that the vaccine has efficacy for.

[hereme888]

The shingles virus hides in the nervous system and can come back out when immune control weakens. It causes inflammation and nerve injury, sometimes severe enough to leave people with chronic pain. From there, it’s reasonable to theorize that it could also affect the brain and even its glymphatic system over time.