Replicated association, which is strong, but not proof. Initial study saw a 3.5% absolute reduction in dementia diagnoses over seven years with a very wide confidence interval. In Australia the study was replicated with 1.8% absolute reduction over 7.4 yrs. Canadian replication: 2% over 5.5 yrs.

Infections generally increase the risk of future dementia. Like the more colds you have throughout life.

I'm in my 40s with genetic predisposition for Alzheimer's. Been seriously considering the past year or two paying out of pocket for Shingrix. I think it would be ~$500 total for two doses.

Sure, I could wait 7 or 8 years until I qualify via insurance, but is that really worth the risk for what is an easily absorbed cost to me? Especially when I have a friend in her late 30s who just went through a very rough bout of shingles?

It makes sense to have targets like age 50 for population-wide public health recommendations. But it can and does infect people of much earlier ages.

Recent articles like this make me think I'll go ahead.

TL;DR Shingles vaccines reduces chances of dementia by 20%. Yet, most countries health systems only look at the upfront cost of ~$300 and don’t recommend for all who could benefit.