A study of more than 500,000 older adults has found that the Shingrix shingles vaccine dementia risk association holds up in one of the most vulnerable patient groups examined so far: people entering skilled nursing facilities. Those who received at least one dose of Shingrix were 24% less likely to receive a dementia diagnosis over the following four years compared with those who remained unvaccinated.
The study, published on 16 June in the Annals of Internal Medicine, was led by Kaleen Hayes, an assistant professor at Brown University‘s School of Public Health and associate director of pharmacoepidemiology for Brown’s Centre for Gerontology and Healthcare Research. Researchers from the University of Delaware, the Providence Veterans Affairs Medical Center and other institutions contributed to the work.
What the data actually showed
The analysis drew on Medicare claims and electronic health records from patients admitted to more than 5,500 skilled nursing facilities across the United States between 2017 and 2022. All 509,926 participants were aged 66 or older. Of that group, just 8,843 received the shingles vaccine. Dementia developed in 18.8% of vaccinated participants over four years, compared with 24.6% of those who were not vaccinated.
Hayes translated the gap into plainer terms: ‘This translates to about one in 17 dementia cases potentially being prevented.’ The researchers used a method called target trial emulation, which attempts to recreate conditions close to a randomised clinical trial in situations where running such a trial is not practical.
Shingrix, known formally as the recombinant herpes zoster vaccine (RZV), was introduced in 2017 and is currently the only shingles vaccine on the market. The Juta MedicalBrief notes that the US Centres for Disease Control and Prevention recommends shingles vaccination for all adults over 50 in the United States, meaning the vaccine at the centre of this study is already in widespread use.
Why this study on Shingrix shingles vaccine dementia risk matters beyond the headline
Hayes made a point of distinguishing this work from earlier research. ‘A lot of previous studies with similar results focused on an older vaccine,’ she said. ‘This study looks at the newest vaccine only in an older, vulnerable adult population who were not up to date with shingles vaccination and are at a very clear clinical point in care: entering a skilled nursing facility.’
The consistency with earlier findings on a previous shingles vaccine is part of what makes researchers cautiously interested. ‘It fits into this large puzzle that’s just starting to come together,’ Hayes said, ‘that the vaccines are effective at preventing shingles and also appear to have neuroprotective benefits as well.’
That word ‘appear’ carries real weight here. The study cannot establish that Shingrix itself caused the lower rate of dementia diagnoses. People who received the vaccine tended to be slightly younger and healthier than those who did not, which could independently lower their dementia risk. The researchers adjusted for those differences and found they did not fully account for the association, but residual confounding cannot be ruled out. Clinical trials will be needed before any causal claim is warranted.
The funding question
The authors reported receiving funding from GlaxoSmithKline, the manufacturer of Shingrix. They stated that the company had no control over the study design, the analysis or the decision to publish. Readers can weigh that disclosure as they see fit; it does not invalidate the findings, but it is a fact worth holding alongside them.
Hayes framed the broader implication carefully. ‘Our cognition is so tied to our overall health and what happens to us physically,’ she said. ‘It’s really amazing to see that something that’s supposed to prevent a physical ailment can also help keep our brain healthy, too.’ Whether ‘amazing’ survives a randomised trial is the question the field now needs to answer.
As Yahoo News reported, the paper was published on 16 June in the Annals of Internal Medicine. The researchers say additional studies, including clinical trials, are needed to confirm whether the Shingrix shingles vaccine dementia risk reduction they observed reflects a genuine protective mechanism or a pattern that further investigation will complicate.
