A new shingles vaccine could reduce dementia risk by 17%, according to a new study published by researchers at Oxford University in England.
The study, which involved 200,000 people, found that those who received the Shingrix vaccine had a lower risk of dementia compared to those with the older Zostavax shingles vaccine. Compared to other vaccines, the Shingrix vaccine reduced dementia risk by between 23% and 27%.
“The size and nature of this study make these findings convincing and should motivate further research. They support the hypothesis that vaccination against shingles might prevent dementia. If validated in clinical trials, these findings could have significant implications for older adults, health services, and public health,” said NIHR Academic Clinical Lecturer Dr. Maxime Taqu.
This adds five to nine additional months of life for those without dementia, with the benefit of a lowered dementia risk being higher in women.
Researchers said that more work is needed before a recommendation can be made to show that the shingles vaccine could directly prevent dementia risk.
Shingles, caused by the herpes zoster virus, can recur in individuals who have had chickenpox in the past. When the shingles vaccine, Zostavax, was introduced in 2006, several studies suggested that those who received the vaccine might have a reduced risk of developing dementia.
The Oxford team studied the health records of over 200,000 residents in the U.S. Those who developed dementia lived an additional six months, but more work is needed to study these changes.
John Todd, Professor of Precision Medicine at the University of Oxford’s Nuffield Department of Medicine, said: “A key question is, how does the vaccine produce its apparent benefit in protecting against dementia? One possibility is that infection with the herpes zoster virus might increase the risk of dementia, and therefore by inhibiting the virus, the vaccine could reduce this risk. Alternatively, the vaccine also contains chemicals that might have separate beneficial effects on brain health.”
Those given Shingrix had a 23 to 27% lower risk of dementia compared to individuals who were vaccinated against flu, tetanus, diphtheria, or pertussis. However, the ways in which the vaccine reduces dementia risk remain unknown, and further research is needed.
One possibility is that the reactivation of the virus in shingles could cause pathological changes leading to dementia. Another possibility is that adjuvants—substances in the vaccine that enhance the immune response—might be involved, researchers said.
“The findings are intriguing and encouraging. Anything that might reduce the risk of dementia is to be welcomed, given the large and increasing number of people affected by it,” said study supervisor Paul Harrison, a professor of psychiatry.
