 "Shingles vaccine may cut dementia risk by 20%, especially in women: Study")
The shingles vaccine could reduce the risk of dementia by a fifth, with women likely to experience a stronger protective effect, according to a recent study led by the Stanford University School of Medicine, United States.
“We show that receiving the zoster vaccine reduced the probability of a new dementia diagnosis over a follow-up period of seven years by 3.5 percentage points, corresponding to a 20 per cent relative reduction,” the study quoted the authors as saying.
“This protective effect was stronger among women than men,” it added.
The study, titled A natural experiment on the effect of herpes zoster vaccination on dementia, published in the journal Nature, analysed the health records of more than 280,000 older adults in Wales, aged between 71 and 88, who did not have dementia when the country’s shingles vaccination programme began in 2013.
To minimise the impact of individual lifestyle factors and make it as close to a randomised controlled trial as possible without actually being one, the researchers used a natural experiment setup. They compared individuals who turned 80 just before September 1, 2013, making them eligible for the limited vaccine supply. ALSO READ | Diabetes in pregnancy linked to higher risk of autism in children: Lancet
Over the seven-year follow-up, the team found that the shingles vaccine reduced the occurrence of shingles by 37 per cent and dementia by 20 per cent.
By 2020, one in eight adults aged 86 and 87 had been diagnosed with dementia. However, vaccinated individuals were significantly less likely to develop the condition.
The stronger protective effect observed in women could be attributed to sex-related differences in immune responses. Women are known to have higher antibody responses to vaccines, and shingles is more common among them.
Shingles, or herpes zoster, is caused by the varicella-zoster virus—the same virus responsible for chickenpox. The virus can reactivate years later, leading to painful rashes and, in some cases, long-term nerve pain. ALSO READ | Obesity cure is here? Why it could be a win-win for all stakeholders
The findings support the theory that certain viruses affecting the nervous system may raise the risk of dementia, a condition that impairs memory, thinking, and cognition with age.
According to the researchers, if the results are replicated in future studies, shingles vaccination could be used as a preventive intervention against dementia, which affects millions globally, placing a growing burden on health systems.