A vaccine against shingles may also offer protection against dementia, according to a new study.
Among more than 200,000 study participants, those who received the newer shingles vaccine Shingrix were 17 percent less likely to develop dementia compared to people who received Zostavax, an older and less-effective shingles vaccine, according to results published in
Nature Medicine.
These findings support the theory that vaccination against shingles might help prevent dementia, says the lead author, Maxime Taquet, BMBCh, PhD, a bachelor of medicine and bachelor of surgery and a clinical lecturer in the department of psychiatry at Oxford University in England.
“If the findings are validated in clinical trials, it could have significant implications for older adults, health services, and public health. Dementia is an important public health challenge, with millions of people affected and without effective treatments to prevent or even delay its onset,” says Dr. Taquet.
It’s estimated that nearly 1 in 10 U.S. adults age 65 and older have dementia.
The Newer Shingles Vaccine Is Linked With 5 to 9 Months Lived Without Dementia
In October 2017, U.S. healthcare providers stopped using Zostavax and replaced it with a newer, more effective vaccine, Shingrix. What makes the newer vaccine different is that it contains inactive zoster virus cells and an immune system booster, while the older vaccine contains live virus cells. This switchover allowed the researchers to compare the risk of dementia for different versions of the vaccine.
People who received Shingrix were also compared with people who had received vaccines against other infections, including the flu, tetanus, diphtheria, and pertussis (also called whooping cough).
The study included 201,064 participants with an average age of 71. About half received Shingrix and the other half got the older vaccine. The groups were very similar, apart from the type of vaccine received and when those vaccines were administered.
The study’s key findings included:
- Shingrix was associated with 17 percent lower risk of dementia than Zostavax, and a 23 to 27 percent lower risk than other vaccines included in the study.
- The risk reduction translated into five to nine more months lived without dementia for the Shingrix group, according to the authors.
- A lower risk of dementia was seen in both men and women who received Shingrix, but there was a 9 percent greater protective effect for women, a finding that needs further study, said researchers.
Although the study wasn’t designed to uncover why the newer vaccine was better at reducing dementia risk, two hypotheses can be considered, says Taquet: It’s possible that shingles can lead to dementia, so preventing one can prevent the other, he says. On the other hand, the newer vaccine contains an ingredient called an adjuvant that stimulates the immune system, “and it might be that this stimulation helps prevent dementia,” he says.
This study investigates a very important question, given the increasing evidence that shingles vaccination may have benefits for the dementia disease process, says Pascal Geldsetzer, MD, PhD, MPH, an assistant professor of medicine in primary care and population health at Stanford Medicine in Palo Alto, California.
Dr. Geldsetzer was the lead author in a previous study on the shingles vaccine and dementia risk, but was not involved in the latest research.
There are certain factors that could have influenced the findings, he says: People who are more “health-motivated” may have put off getting vaccinated against shingles with the older vaccine because they knew they’d be able to receive the newer and more effective one in the near future.
“The authors are only able to account for such differences using information that is contained in electronic health record data. Unfortunately, that misses many important factors, such as physical activity or dietary behaviors. The authors are very transparent about these limitations and, in my view, did the best they could with the data at hand,” says Geldsetzer.
Both Taquet and Geldsetzer agree that more research is needed.
“A large-scale randomized trial will be needed before we can be entirely confident that shingles vaccination really does reduce the risk of dementia,” says Geldsetzer.
Who Should Get Shingrix?
Older people should get the shingles vaccine if they are eligible, says Taquet.
“We do not recommend taking it solely because it might prevent dementia, even though this might serve as an additional incentive,” he says.
The Centers for Disease Control and Prevention recommends that people age 50 and older should get two doses of Shingrix, separated by two to six months.
Adults 19 years and older who have or will have weakened immune systems because of disease or therapy should also get two doses of Shingrix. Depending on a doctor’s advice, people with weakened immune systems can get the second dose one to two months after the first.
Adults with weakened immune systems and no documented history of chicken pox disease, chicken pox vaccination, or shingles should talk to their healthcare provider before getting Shingrix.
People who have had a severe allergic reaction to any ingredient in Shingrix, currently have shingles, or who are pregnant should not get the vaccine.
How Are Shingles and Chicken Pox Related?
Chickenpox and shingles are caused by the same virus (varicella-zoster virus). After a person recovers from chickenpox, the virus stays dormant (inactive) in the body — but it can reactivate years later and cause shingles.
Shingles is a painful and serious condition that’s most common in people over 50 and people with a weakened immune system.
Experts estimate that more than 99 percent of Americans born in 1980 or before have had chicken pox, even if they don’t remember having the disease.
