1. Shingles vaccination showed lower dementia rates in U.S. adults.
2. Live-attenuated vaccine reduced dementia risk by 33 percent.
3. Recombinant vaccine lowered dementia risk by 27 percent.
4. Recurrent shingles increased dementia likelihood over time.
5. Vaccine protection waned with the live-attenuated vaccine.
6. Observational design limited causal interpretation.

Source: Nature Medicine