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A vaccine against the viral infection shingles potentially lowers the risk of dementia, scientists have found, in the latest research suggesting existing drugs could help combat brain disorders.
People jabbed with Shingrix, which is manufactured by pharmaceuticals company GSK, lived an average of 164 more days without a dementia diagnosis than a cohort given a predecessor shingles vaccine.
The research highlights how more extensive monitoring of bulk health data is revealing possible unexpected effects of established therapies on apparently unrelated problems. Diabetes and weight loss drugs are a focus of growing interest over their potential impact on Parkinson’s disease and other historically untreatable neurodegenerative conditions.
The size and nature of the shingles study, which involved 200,000 people, made the findings “convincing” and should trigger further research, said Maxime Taquet, leader of the work and a clinical lecturer in Oxford university’s psychiatry department.
“They support the hypothesis that vaccination against shingles might prevent dementia,” Taquet said. “If validated in clinical trials, these findings could have significant implications for older adults, health services and public health.”
Shingles, also known as herpes zoster, results from reactivation of the varicella-zoster virus that causes chickenpox in childhood. Immunity to the dormant virus wanes as people age, so Shingrix offsets this decline.
The latest research, published in Nature Medicine on Thursday, examined the impact of US health systems switching from a previous vaccine named Zostavax to Shingrix in 2017. This allowed the scientists to compare the dementia rates for two cohorts of more than 100,000 people in the six years after they received one of the vaccines.
In the study, Shingrix had a 17 per cent lower risk of dementia than Zostavax and a lower risk of between 23 and 27 per cent than vaccines against other infections, such as flu and tetanus. The beneficial impact was greater for women than for men.
Previous studies have suggested Zostavax may reduce the risk of dementia, but the latest results indicate Shingrix — a so-called recombinant vaccine that uses DNA technology — could be even more effective, scientists said.
The findings suggested tackling the herpes zoster virus could be a “promising strategy” towards tackling dementia and one that should be “vigorously pursued”, said Andrew Doig, professor of biochemistry at Manchester university.
“Now, we need to run a clinical trial of the recombinant vaccine, comparing patients who receive the vaccine with those who get a placebo,” said Doig, who was not involved in the research. “We also need to see how many years the effect might last and whether we should vaccinate people at a younger age.”
Further study would be “critical” to establish not only if Shingrix worked against dementia but to establish how it achieved the effect biologically, said Sheona Scales, director of research at the Alzheimer’s Research UK charity.
“While research into whether vaccines affect dementia risk continues, people should be aware that there are other factors that have definitively been linked to an increased dementia risk,” Scales said, pointing to smoking, high blood pressure and excessive alcohol consumption.
Shingrix is one of GSK’s best selling products, generating £3.4bn revenue worldwide in 2023. The new study added to the “growing body of evidence that suggests an association between shingles vaccination and reduced risk of dementia”, the UK-based company said.
GSK will present its own new data on Shingrix at an Alzheimer’s conference in Philadelphia next week.