Large trial ties shingles vaccine to lower dementia risk

Adults who received the recombinant shingles vaccine were 18 percent less likely to be diagnosed with dementia over seven years, according to a 280,000-person study published on Wednesday — the strongest evidence yet for a link researchers have circled for years.

The study exploited a natural experiment created by staggered eligibility rules, allowing comparison of otherwise similar cohorts on either side of the cutoff. The protective association held across sexes and was strongest for vascular dementia.

Researchers cautioned the mechanism remains unclear — candidates include suppression of the varicella virus itself and broader immune effects — and said a randomized prevention trial is now both feasible and warranted.