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Shingles vaccine recipients less likely to develop dementia, study shows
Stephanie Soucheray, MA
Today at 3:38 p.m.
Misc Emerging Topics A study yesterday in Nature adds to the growing body of evidence that shingles vaccines are protective against dementia.
In the study, researchers from Stanford Medicine and the Vienna University of Economics and Business in Austria analyzed the health records of Welsh adults 71 to 88 years old and discovered that those who received the shingles vaccine were 20% less likely to develop dementia over the next 7 years than those who did not receive the vaccine. Shingles, which causes a painful rash among other symptoms, is a reactivation of the varicella-zoster virus, which most older adults contracted in childhood as chickenpox.
The authors said previous studies linking vaccines to better health outcomes including dementia are problematic, because people who get vaccines tend to be more health-conscious in general.
"All these associational studies suffer from the basic problem that people who get vaccinated have different health behaviors than those who don't," said Pascal Geldsetzer, MD, PhD, assistant professor of medicine and senior author of the new study, in a press release from Stanford Medicine. "In general, they're seen as not being solid enough evidence to make any recommendations on."
Natural experiment in Wales
But in Wales, health authorities rolled out the shingles (herpes zoster) vaccine in an interesting manner to manage supply: Beginning in 2013, adults who were 79 by September 1 were eligible for the vaccines. Each year, only 79-year-olds were eligible, and eligibility lasted for 1 year. People who were 80 or older on September 1, 2013, would never become eligible for the vaccine.
"What makes the study so powerful is that it's essentially like a randomized trial.
"What makes the study so powerful is that it's essentially like a randomized trial with a control group—those a little bit too old to be eligible for the vaccine—and an intervention group—those just young enough to be eligible," Geldsetzer said.
Using health records, the researchers tracked health outcomes through 2020 for those who were 80 in 2013 and those who were 79 and thus able to receive the shingles vaccine. During the follow-up period of 7 years, 14,465 people among 296,324 adults in the study sample had at least one diagnosis of shingles.
Overall, receiving the 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 to 7.1).
That corresponded to a 20% relative reduction in developing dementia, and the effect was strongest in women.
The authors said there were three possible protective effects of shingles vaccination on dementia diagnoses, including changes in healthcare pathways as a result of a shingles episode; a reduction in reactivations of the varicella zoster virus (VZV); and a VZV-independent immunomodulatory effect. The immunomodulatory effect could explain why women were more protected than men, despite being just as likely as men to have received a shingles vaccine, they said.
Shingles vaccine recipients less likely to develop dementia, study shows
Stephanie Soucheray, MA
Today at 3:38 p.m.
Misc Emerging Topics A study yesterday in Nature adds to the growing body of evidence that shingles vaccines are protective against dementia.
In the study, researchers from Stanford Medicine and the Vienna University of Economics and Business in Austria analyzed the health records of Welsh adults 71 to 88 years old and discovered that those who received the shingles vaccine were 20% less likely to develop dementia over the next 7 years than those who did not receive the vaccine. Shingles, which causes a painful rash among other symptoms, is a reactivation of the varicella-zoster virus, which most older adults contracted in childhood as chickenpox.
The authors said previous studies linking vaccines to better health outcomes including dementia are problematic, because people who get vaccines tend to be more health-conscious in general.
"All these associational studies suffer from the basic problem that people who get vaccinated have different health behaviors than those who don't," said Pascal Geldsetzer, MD, PhD, assistant professor of medicine and senior author of the new study, in a press release from Stanford Medicine. "In general, they're seen as not being solid enough evidence to make any recommendations on."
Natural experiment in Wales
But in Wales, health authorities rolled out the shingles (herpes zoster) vaccine in an interesting manner to manage supply: Beginning in 2013, adults who were 79 by September 1 were eligible for the vaccines. Each year, only 79-year-olds were eligible, and eligibility lasted for 1 year. People who were 80 or older on September 1, 2013, would never become eligible for the vaccine.
"What makes the study so powerful is that it's essentially like a randomized trial.
"What makes the study so powerful is that it's essentially like a randomized trial with a control group—those a little bit too old to be eligible for the vaccine—and an intervention group—those just young enough to be eligible," Geldsetzer said.
Using health records, the researchers tracked health outcomes through 2020 for those who were 80 in 2013 and those who were 79 and thus able to receive the shingles vaccine. During the follow-up period of 7 years, 14,465 people among 296,324 adults in the study sample had at least one diagnosis of shingles.
Overall, receiving the 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 to 7.1).
That corresponded to a 20% relative reduction in developing dementia, and the effect was strongest in women.
The authors said there were three possible protective effects of shingles vaccination on dementia diagnoses, including changes in healthcare pathways as a result of a shingles episode; a reduction in reactivations of the varicella zoster virus (VZV); and a VZV-independent immunomodulatory effect. The immunomodulatory effect could explain why women were more protected than men, despite being just as likely as men to have received a shingles vaccine, they said.