This shot can slow progression of dementia if you have it: study

Worth a shot?

Over 6 million Americans live with dementia, a progressive condition that affects memory, reasoning, judgment and language skills.

There is no known cure for dementia, but new research suggests that a common vaccine may help prevent its onset and slow its progression.

An April Stanford Medicine study found that people inoculated against shingles were 20% less likely to develop dementia than unvaccinated individuals.

A follow-up study published this week determined that those who already have dementia may also benefit from the vaccine.

“This really suggests the shingles vaccine doesn’t have only preventive, delaying benefits for dementia, but also therapeutic potential for those who already have dementia,” said Dr. Pascal Geldsetzer, a Stanford assistant professor of medicine and senior author of the new study.

What is shingles?

The varicella-zoster (VZV) virus causes shingles and chickenpox, a common childhood disease.

Even when a child recovers from chickenpox, VZV remains dormant in their nerve tissue and can reactivate years later as shingles.

Shingles is characterized by a painful, blistering rash typically on one side of the body. It’s rarely deadly, but it can lead to complications like persistent nerve pain, skin infections, vision loss or hearing problems.

The shingles vaccine, which is designed to prevent VZV from reactivating, is generally recommended for healthy adults 50 and older and any adults with a weakened immune system.

Previous research has linked the shingles vaccine to significantly lower dementia rates, but researchers pointed out that people who get this vaccine tend to be health-conscious and potentially less likely to develop dementia.

“All these associational studies suffer from the basic problem that people who go get vaccinated have different health behaviors than those who don’t,” Geldsetzer said. “In general, they’re seen as not being solid enough evidence to make any recommendations on.”

How can the shingles vaccine help in the battle against dementia?

Geldsetzer’s team turned to Wales for answers.

The UK country started a unique shingles vaccination program in 2013 that set age requirements for eligibility, which meant that some healthy people were not able to get the shot.

This system “seemed to sidestep” the bias of previous studies.

In evaluating the health records of more than 280,000 seniors, Geldsetzer and his colleagues found that vaccinated individuals were 20% less likely to develop dementia within seven years compared to their unvaccinated peers.

This number held even when looking at other factors, including age and education level.

“It was a really striking finding,” Geldsetzer said. “This huge protective signal was there, any which way you looked at the data.”

One idea is that the vaccine helps to prevent shingles and its potential side effects, such as inflammation that can harm the brain and stroke. Stroke is a major risk factor for dementia.

Other benefits of the shingles vaccine

The Stanford study also found that:

• Vaccinated individuals were less likely to be diagnosed with mild cognitive impairment within nine years of vaccination.
• Dementia patients who received the vaccine after their diagnosis were significantly less likely to die from dementia within nine years.
• Vaccinated women were more protected against dementia than vaccinated men, which Geldsetzer theorized could be because women tend to have higher antibody responses to vaccination. Shingles is also more common in women than in men.

Geldsetzer said these results, published in the journal Cell, have been replicated in other countries. Nevertheless, he’s eyeing a large, randomized controlled trial that would randomly assign participants the vaccine or a placebo shot.

“It would be a very simple, pragmatic trial because we have a one-off intervention that we know is safe,” he said.