BOSTON — About two-thirds of Americans eligible to get vaccinated against shingles haven’t done so. But the results of a new study might persuade some to get the shots. Because it appears shingles vaccination may significantly reduce the risk of developing dementia.
“I think dementia is going to be THE public health problem in the future for aging societies, such as the U.S.,” said study author Pascal Geldsetzer, MD, PhD of Stanford University.
Actually, dementia is already a significant problem. The Alzheimer’s Association reports nearly seven million Americans have that disease — with half a million new cases diagnosed each year. With an aging population, the annual incidence of dementia could double in the next 30 years.
But is it possible to put a significant dent in the number of new cases? Geldsetzer said his group’s research found getting vaccinated against shingles resulted in a 3.5% drop in expected new cases of dementia — which translates to a 20% reduction in risk. Women appeared to benefit more from the vaccination than men.
The study examined medical records from nearly 300,000 Welsh adults — that population chosen because the shingles vaccine was absolutely apportioned in Wales by date of birth. Those born before September 2, 1933 were ineligible for life to receive the vaccine; those born after that date had one year to get it. That meant researchers studied naturally occurring randomized population groups — one vaccinated, the other not.
So why would shingles vaccination possibly hinder dementia?
Geldsetzer said the key is in the nature of the herpes zoster virus — which causes chickenpox in childhood, then remains dormant in the central nervous system for life.
Dormant does not mean devoid of activity. In fact, far from it.
“We know it is a virus that is constantly reactivating through life, being beaten back down by the immune system, in this constant interplay with the immune system,” said Geldsetzer. “And we know that this causes some inflammatory processes. Inflammation is a bad thing for chronic diseases, including dementia.”
That’s one possible avenue for dementia protection. There may be another.
“There’s also an increasing body of research showing vaccines have a broader effect on the immune system beyond the specific antibody response they’ve been designed to elicit,” Geldsetzer said.
“It’s a readily available, inexpensive, one-off intervention,” he said.
But it’s an intervention many eligible adults have avoided — in part, because shingles vaccination has a reputation of producing uncomfortable side effects — mostly pain at the injection site, though others report malaise and nausea.
Those side effects are considered harmless.
Geldsetzer said the next step is to conduct a true, randomized clinical trial. He and his group are hoping a philanthropist will see value in research that could effectively address one of the world’s most puzzling diseases.
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