People who get vaccinated against shingles at age 70 may reduce their risk of dementia over the next seven years, suggests one analysis.
However, an expert told Live Science that the study is missing a key analysis, the omission of which casts doubt on the strength of the findings.
Mounting evidence suggests that viral infections may increase the risk of later dementia, a condition that impairs the ability to remember, think and make decisions and they affect about 5.8 million people in the United States Specifically, research has shingles-related infectionscaused by the varicella-zoster virus which also causes chickenpox, at an increased risk of dementia, although some studies suggest that this link may not exist.
After invading the body, varicella-zoster viruses hide inside specific nerve cells, where they can lie dormant for decades while being kept in check by the immune system. Later in life, when the immune system is functioning less effectively, viruses can reactivate and wreak havoc shinglesa condition characterized by a painful, blotchy rash that typically appears on one side of the body or face.
Related: One man’s rare genetic variant may have protected him from a devastating form of early Alzheimer’s
In theory, it’s the inflammation and other yet-to-be-unknown bodily changes resulting from varicella-zoster reactivation that may increase the risk of dementia, she said Ruth Itzhakiemeritus professor of molecular neurobiology at the University of Manchester, who was not involved in the new study.
In support of this theory, previous studies have found lower dementia rates among people who received the shingles vaccine Zostavax compared to unvaccinated people. However, these studies often assume that any differences in dementia risk are due to vaccination status. In reality, other factors, such as a person’s likelihood of following diet and exercise recommendations, also play a role and thus muddy the waters of how vaccination, alone, affects disease risk.
To get around this problem, the scientists have now analyzed medical records collected from people aged 70 and over, who lived in Wales during the launch of the Zostavax vaccine in September 2013. People born on or after 2 September 1933 were eligible for the shot, while those born before were ineligible. The results of the analysis, which have yet to be peer reviewed, were published on May 25 on the prepress server medRxiv.
About 50 percent of people born in the year after the eligibility cutoff date received the shot during the rollout, the scientists found, and those eligible for the vaccine had lower rates of shingles than those who didn’t. they were suitable. They then compared rates of dementia in people born in the year before the cutoff date with those born within about a year after, over a period of seven years after vaccination. In total, this analysis included more than 56,000 people.
Vaccine-eligible people were 8.5 percent less likely to be diagnosed with dementia in the follow-up period than those ineligible. Through further analyses, the scientists estimated that people who were eligible and effectively vaccinated had an approximately one-fifth lower risk of being diagnosed with dementia, compared to the ineligible group.
However, the scientists did not directly compare dementia rates between eligible and vaccinated people with those eligible and unvaccinated.
“They have the data to answer this question, but provide a convoluted and weak logic to justify why they didn’t,” which opens questions about why they didn’t present it, Doctor Devangere Devanand, a professor of psychiatry and neurology at Columbia University Medical Center in New York, told Live Science in an email. However, even with this omission, the findings still add to the idea that shingles may increase the risk of dementia, Devanand said.
“They used a new method to add further evidence to the idea that viruses can increase the risk of Alzheimer’s disease and dementia both through direct damage [to the brain] or inflammation, which has been supported by many other studies,” Itzhaki told Live Science.
“I think all these vaccination results [from the current and previous studies] they’re very exciting,” Itzhaki said.
(Note that a new, more protective shingles vaccine called Shingrix is now recommended over Zostavax in the United States, and the study does not address Shingrix’s effect on dementia risk, the authors noted.)
#shingles #vaccine #protect #dementia