Herpes zoster vaccination and cognitive disorders in older adults.

INTRODUCTION

Previous studies suggested a reduced risk of dementia after live zoster vaccination, but were limited by short follow-up and narrow populations. This study assessed the long-term association between live zoster vaccination and memory disorders and Alzheimer's disease (AD) in a nationwide Korean cohort.

METHODS

This study, using linked national databases, included 2.5 million adults aged ≥ 50 years from 2012 to 2024. After exposure-based overlap weighting, Cox models estimated adjusted hazard ratios (aHRs) and restricted mean survival time (RMST).

RESULTS

Among 1,041,964 participants (mean age, 61.8 years; 46.1% male), vaccination was associated with lower risks of memory disorders (aHR 0.88; 95% confidence interval: 0.87-0.90) and AD (0.75, 0.71-0.78), corresponding to RMST gains of 15.5 and 11.3 days per decade, respectively. Protective effects attenuated over time and were less pronounced among smokers and drinkers.

DISCUSSION: Live zoster vaccination was associated with delayed onset of cognitive decline, suggesting benefits beyond herpes zoster prevention in aging populations.