An analysis of thousands of medical records shows that people who get the shingles vaccine in their 70s may have a reduced risk of dementia over the next seven years. However, one expert said in a statement that important analysis was missing from the study, which casts doubt on the validity of the findings.
There is growing evidence that viral infections can increase the risk of dementia later in life – conditions that affect memory, thinking, and decision-making, affecting approximately 5,8 million people in the United States. Although studies have shown that shingles infections caused by the varicella-zoster virus, which also causes chickenpox, increase the risk of dementia, some studies suggest that this link may not exist.
The inflammation and other as yet unidentified bodily changes caused by varicella-zoster reactivation may increase the risk of dementia, according to Ruth Itzhaki, emeritus professor of molecular neurobiology at the University of Manchester, who was not involved in the new study.
Previous research has demonstrated lower rates of dementia among those who took Zostavax than those who did not, supporting this theory. However, these studies are often based on the assumption that differences in dementia risk are dependent on vaccination status.
In reality, additional factors, such as a person's propensity to follow dietary and exercise guidelines, also come into play, blurring the picture of how vaccination alone affects disease risk.
To circumvent this issue, the researchers analyzed medical information collected from patients in their late 2013s and older residing in Wales at the time the Zostavax vaccine became available in September 70.
Those born before September 2, 1933 were not eligible for the vaccine, while those born on or after this date were eligible. The findings of the analysis were published May 25 on the medRxiv preprint platform; It has not yet passed peer review.
Researchers discovered that at the time of vaccine rollout, about 50% of those born one year after the vaccination qualifier were vaccinated, and that shingles was less common in those who were vaccinated than those who did not.
They then compared the prevalence of dementia seven years after vaccination among those born one year before the vaccination date with those born approximately one year later. Our research included more than 56.000 people in total.
Compared to those who were ineligible for the vaccine, these people were 8,5% less likely to be diagnosed with dementia during the follow-up period.
Through additional analysis, the researchers calculated that those who qualify and get vaccinated have about one-fifth a lower risk of developing dementia than those who do not.
However, the scientists did not directly compare the incidence of dementia between those who qualify and are vaccinated and those who qualify but are not vaccinated.
A professor of psychiatry and neurology at Columbia University Medical Center in New York, Dr. According to Devangere Devanand, “They have the data to address this question but provide a convoluted, weak justification for why they didn't do it,” which raises concerns about why they didn't. Despite this omission, Devanand said the findings support the hypothesis that shingles may increase the risk of dementia.
Itzhaki told Live Science that the researchers "used a new method to add further evidence to the idea that viruses can increase the risk of Alzheimer's disease and dementia by either direct damage to the [brain] or through inflammation, which is supported by many other studies."
Itzhaki said: “I think all these vaccination results [from recent and previous trials] are quite promising.
📩 06/06/2023 16:41