Shingles Vaccine May Reduce Dementia Risk and Could Slow Disease Progression

The shingles vaccine has long been suspected of having an impact on developing dementia. However, strong evidence through clinical trials to confirm suspicions on the vaccine’s protective effects on the neurodegenerative disease was lacking.

Now, researchers from Stanford Medicine report in Nature and Cell that people who received the shingles vaccine were about 20 percent less likely to develop dementia than those who did not. The analysis, based on Welsh health records, also found that vaccinated individuals diagnosed with dementia were less likely to die from the disease, suggesting the shot may influence disease progression as well as risk.

Read More: Why are Painful Blisters From Shingles Appearing on People Under 50?

Why Shingles Might Matter for Dementia

The varicella-zoster virus, which causes chickenpox in childhood, remains dormant in the nervous system long after the initial infection resolves. In older age, the virus can reactivate as shingles, which can sometimes lead to severe neurological complications.

In recent years, researchers have increasingly explored the possibility that viruses affecting the nervous system may contribute to dementia risk. With millions of people worldwide living with dementia, identifying modifiable risk factors has become a public health priority.

According to the study’s press release, previous studies had reported associations between shingles vaccination and lower dementia rates. However, those findings came with major uncertainty:

“All these associational studies suffer from the basic problem that people who go get vaccinated have different health behaviors than those who don’t,” said senior study author Pascal Geldsetzer, assistant professor at the Division of Primary Care and Population Health of Stanford University, in the news release. “In general, they’re seen as not being solid enough evidence to make any recommendations on.”

Unusual Vaccination Program Provides Solid Data on Dementia

A quirk in public health policy allowed the Stanford team to overcome that limitation.

In 2013, Wales faced a shortage of the shingles vaccine and limited eligibility to people who were 79 years old on September 1 of that year — for one year only. Those who had already turned 80 were permanently excluded.

As a result, eligibility hinged entirely on a narrow birthdate cutoff, not health status or personal choice, and researchers were able to isolate the impact of vaccination itself.

“Because of the unique way in which the vaccine was rolled out, bias in the analysis is much less likely than would usually be the case,” said Geldsetzer.

The study analyzed records from more than 280,000 adults aged 71 to 88 who were dementia-free at the start. Over seven years, vaccinated individuals experienced a 37 percent reduction in shingles cases and a 20 percent reduction in dementia risk.

“What makes the study so powerful is that it’s essentially like a randomized trial with a control group — those a little bit too old to be eligible for the vaccine — and an intervention group — those just young enough to be eligible,” he added. “It was a really striking finding. This huge protective signal was there, any which way you looked at the data.”

Potential of Shingles Vaccine to Slow Dementia Progression

Additional analysis suggested benefits beyond delaying onset. Vaccinated individuals were less likely to be diagnosed with mild cognitive impairment, and those vaccinated after a dementia diagnosis were significantly less likely to die from the disease during nine years of follow-up.

“The most exciting part is that this really suggests the shingles vaccine doesn’t have only preventive, delaying benefits for dementia, but also therapeutic potential for those who already have dementia,” Geldsetzer said.

The biological mechanism remains unknown, though immune system effects or reduced viral reactivation are possible explanations. Geldsetzer and his colleagues are now calling for a large randomized clinical trial to determine whether the relationship is causal.

This article is not offering medical advice and should be used for informational purposes only.

Read More: A New mRNA Vaccine Has the Potential to Cure Seasonal and Food Allergies

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article: