New research: Shingles vaccine reduces risk of developing dementia by 20%

New research reveals that the shingles vaccine might play a role in reducing the risk of developing dementia. The study was led by a team of scientists at Stanford Medicine and involved analyzing a vaccination program in Wales. Researchers found that the shingles vaccine lowered new dementia diagnoses by 20%, which is more than any other currently known prevention or intervention.

Stanford Medicine provides more details:

Researchers analyzing the health records of Welsh older adults discovered that those who received the shingles vaccine were 20% less likely to develop dementia over the next seven years than those who did not receive the vaccine.

The remarkable findings, published April 2 in Nature, support an emerging theory that viruses that affect the nervous system can increase the risk of dementia. If further confirmed, the new findings suggest that a preventive intervention for dementia is already close at hand.

Since the Welsh study, the Stanford Medicine research team has examined health records from England, Australia, New Zealand, and Canada, and has found similar results indicating that the shingles vaccine provides protection from developing dementia. The researchers are currently planning to conduct a large randomized controlled trial, which "would provide the strongest proof of cause and effect." 

Here's the study's full abstract, from Nature:

Neurotropic herpesviruses may be implicated in the development of dementia1,2,3,4,5. Moreover, vaccines may have important off-target immunological effects6,7,8,9. Here we aim to determine the effect of live-attenuated herpes zoster vaccination on the occurrence of dementia diagnoses. To provide causal as opposed to correlational evidence, we take advantage of the fact that, in Wales, eligibility for the zoster vaccine was determined on the basis of an individual's exact date of birth. Those born before 2 September 1933 were ineligible and remained ineligible for life, whereas those born on or after 2 September 1933 were eligible for at least 1 year to receive the vaccine. Using large-scale electronic health record data, we first show that the percentage of adults who received the vaccine increased from 0.01% among patients who were merely 1 week too old to be eligible, to 47.2% among those who were just 1 week younger. Apart from this large difference in the probability of ever receiving the zoster vaccine, individuals born just 1 week before 2 September 1933 are unlikely to differ systematically from those born 1 week later. Using these comparison groups in a regression discontinuity design, we show that receiving the zoster vaccine reduced the probability of a new dementia diagnosis over a follow-up period of 7 years by 3.5 percentage points (95% confidence interval (CI) = 0.6–7.1, P = 0.019), corresponding to a 20.0% (95% CI = 6.5–33.4) relative reduction. This protective effect was stronger among women than men. We successfully confirm our findings in a different population (England and Wales's combined population), with a different type of data (death certificates) and using an outcome (deaths with dementia as primary cause) that is closely related to dementia, but less reliant on a timely diagnosis of dementia by the healthcare system10. Through the use of a unique natural experiment, this study provides evidence of a dementia-preventing or dementia-delaying effect from zoster vaccination that is less vulnerable to confounding and bias than the existing associational evidence.

Sadly, this exciting research comes on the heels of the Trump administration slashing budgets and firing thousands of scientists from the National Institutes of Health who were conducting research into cancer, Alzheimer's, HIV, and other devastating diseases.

To read more about the study, here's a great overview of the research on the Stanford Medicine website, or read the full study in Nature here. And go get your shingles vaccines if you're due!

Previously: Watch Shingle Jingle, the best way to experience shingles