08-04-2025
- Health
- National Geographic
The shingles vaccine may reduce your dementia risk—here's why
While there is currently no way to prevent the onset of dementia, the shingles vaccine could potentially change that. This color-enhanced Transmission Electron Micrograph (TEM) shows the varicella zoster virus (VZV), a virus in the Herpesviridae family that causes chickenpox in children and shingles (herpes zoster) in adults. Micrograph by James Cavallini, Science Photo Library
Shingles, a viral rash, can be incredibly painful. Vaccination can help prevent the infection, but new research is showing the vaccine may also have another benefit: protecting against the development of dementia.
In April, a study published in Nature observed the risk of dementia in adults who received the shingles vaccine versus those who had not. Researchers found that those who were vaccinated against shingles had a 20 percent lower chance of developing dementia. This new evidence is part of a growing body of research linking vaccinations against infections like shingles, the flu, and pneumonia with a reduced risk of dementia, says Paul Schulz, a professor of neurology at UTHealth Houston who was not involved in the study. How researchers developed this study
Approximately one million Americans are diagnosed with shingles every year, according to the Centers for Disease Control and Prevention (CDC), with a small number developing serious complications, the most common being nerve pain. The infection occurs when the varicella-zoster virus, which is responsible for the common childhood illness chickenpox, gets reactivated in the body.
Eligibility for the shingles vaccine is generally limited to adults over 50 or those 19 years and older with weakened immune systems. While there are no precise numbers around vaccination rates, vaccination among adults 60 and over rose from about 7 percent in 2008 to about 35 percent in 2018.
When it comes to dementia, it is estimated that more than 40 percent of Americans may develop dementia at some point in their lives.
(The reason dementia rates are rising is surprisingly simple.)
In recent years, there have been a number of studies showing a link between the shingles vaccine and a reduced risk of dementia. However, these studies 'all had this fundamental limitation that those who get vaccinated are very different from those who don't,' says Pascal Geldsetzer, an epidemiologist and public health researcher at Stanford University School of Medicine, and one of the authors of the study.
Historically, those who choose to get vaccinated often have increased access to healthcare and are generally more health-conscious, all of which can help reduce a person's overall risk of developing dementia. As a result, it has previously been difficult to determine whether the shingles vaccine was related to a reduced dementia risk, or if there was another factor behind it.
(What are the signs of dementia—and why is it so hard to diagnose?)
In an attempt to eliminate other factors in this study, Geldsetzer and his collaborators took advantage of the fact that in Wales, people who were born before September 2, 1933 were never eligible to receive the shingles vaccine, while people born after this date were eligible for one year, after they turned 79 and before they turned 80. For those who were eligible, a little under half received the vaccine. This created a natural experiment, where two very similar groups of people—in terms of age, living environment, and access to healthcare—either did or did not receive the vaccine, with the determining factor being the timing of their birth.
What the researchers found was those born after September 2, 1933 who received the shingles vaccine had a 20 percent lower chance of developing dementia than those who did not receive the vaccine. To rule out any additional factors that might be at play, researchers also looked at healthcare usage among the two groups, including flu vaccination rates, as well as use of cholesterol medication.
'I don't think there is any doubt that what they found is real,' says Paul Harrison, a psychiatry researcher at the University of Oxford. Harrison, though not involved with the study, has also conducted similar research. What these findings may tell us
Researchers are trying to understand why the shingles vaccine might lead to a reduced risk of dementia. '[One] possibility is that the vaccine itself might be triggering an immune response which helps the body fend off or even reverse the mechanism of dementia,' says Maxime Taquet, a clinical lecturer in psychiatry at the University of Oxford, who was not involved in the study.
Last year, Taquet and Harrison published a study in Nature Medicine looking at rates of dementia in those who received an older shingles vaccine versus those who received the new one, taking advantage of the fact that the availability of these vaccines shifted very quickly in the United States in October 2017. This meant that it was largely random as to which vaccine a person received. They found that Shingrix, the newer vaccine, was associated with a 17 percent reduced risk of developing dementia compared to the older vaccine.
While the study from last year found a reduced risk of dementia in the newer vaccine compared to the older vaccine, the recent study found a reduced risk of dementia in people who received the older vaccine compared to no vaccine. Both studies lend support to the idea that getting vaccinated against shingles may protect against developing dementia.
