A recent study has found interesting results regarding the impact of a vaccine available in the British National Health Service on the general health of older adults.
The study showed that the shingles (or herpes zoster) vaccine can significantly reduce the risk of developing dementia.
Shingles is a viral infection that causes a painful skin rash. It is caused by the same virus that causes chickenpox, also known as varicella zoster.
Stanford University researchers analyzed data from more than 280,000 older adults aged 71 to 88 in Wales, comparing the records of those who had received the vaccine with those of others who were over the age of eligibility, and who were 80 or older at the time of the vaccine's introduction. (Since 2013, people aged 70 to 79 in England have been eligible for two doses of the vaccine to reduce their risk of infection.)
Although by 2020, 1 in 8 older adults had been diagnosed with dementia, those who received the shingles vaccine were 20% less likely to develop dementia.
"This was a truly astonishing result," explained Dr. Pascal Gildsetz, who led the study. "The protective signal was very clear, regardless of how the data was analyzed."
This type of study is considered particularly powerful because it includes control groups, such as people who were not eligible for the vaccine due to their age.
The study also confirmed that the vaccine's effect on preventing dementia was greater in women, which may be attributed to women's stronger immune response to vaccines.
Many experts hailed the study as an important step in understanding the relationship between vaccines and dementia prevention. Dr. Henry Brodaty, professor of aging and mental health at the University of New South Wales, said: "There has been long-standing evidence that older adults who receive vaccinations are generally less likely to develop dementia, and this study is the best evidence yet of this."
But there are still unanswered questions. Professor Anthony Hannan, a neuroscientist at the Florey Institute in Melbourne, Australia, noted, "The main question this study doesn't answer is how the shingles vaccine contributed to protection against dementia. The next step is to determine exactly how the vaccine affects dementia prevention and use this information to develop new methods of prevention and treatment."
The Stanford University research team replicated the study's findings in health registries from other countries, including England, Australia, New Zealand, and Canada, which have also undergone similar vaccine rollouts. The team is also investigating whether a newer version of the vaccine, which offers greater protection against shingles, might be more effective in reducing the risk of dementia.