The same vaccine that keeps you safe from shingles could also do wonders for your brain, research out this week suggests.

Scientists at Stanford University and others examined what happened after shingles vaccination was introduced to the country of Wales over a decade ago. They found evidence the shingles vaccine not only reduced people’s risk of developing dementia but also lowered their odds of dying from dementia if they did have it. Boosting your immunity to shingles might offer a broad protective effect against cognitive decline, the researchers say.

“This study suggests that [shingles] vaccination slows or prevents disease progression across the entire disease course of dementia,” they wrote in their paper, published Tuesday in Cell.

A natural experiment

Several studies in recent years have suggested that shingles vaccination has benefits beyond preventing the painful viral illness. But the researchers say their approach has allowed them to look at a natural experiment that occurred in Wales in 2013. That fall, the vaccination program officially began in the country, with clear age restrictions. People born on or after September 2, 1933 (80 years and under) were eligible for at least one year for the shingles vaccine, whereas people born before then were not.

These cut-offs (and the UK’s robust record-keeping) meant the researchers could easily track dementia rates among similar groups of older people right before and after the vaccine became available, with the non-eligible group acting as a sort of control. In a study published this April, the researchers found that vaccinated people were 20% less likely to be diagnosed with dementia over a seven-year period.

This time, however, they were interested in seeing whether the vaccine was linked to better outcomes across the different stages of dementia.

Using the same method, they found that vaccinated people were less likely to develop mild cognitive impairment (MCI), the earliest potential stage of dementia (though many with dementia will first experience MCI, not everyone with MCI will go on to have full-blown dementia). And among diagnosed dementia cases, people vaccinated against shingles were also less likely to ultimately die as a result of their condition.

“That means that the vaccine doesn’t just have a preventive potential, but actually a therapeutic potential as a treatment, because we see some benefits already among those who have dementia,” senior study author Pascal Geldsetzer, an assistant professor of medicine at Stanford, told CNN. “To me, this was really exciting to see and unexpected.”

An already worthwhile vaccine

These findings still can’t definitively prove that the shingles vaccine can affect dementia outcomes. That said, the team’s unique method does get around many of the limitations of observational studies. And taken as a whole, the evidence is mounting that the shingles vaccine has more health benefits than we initially realized.

Just this past October, for instance, a study found that people vaccinated for shingles are also less likely to develop heart disease and stroke; they were also less likely to die earlier compared to non-vaccinated individuals.

Shingles is one of the most painful experiences a person can have. And the vaccine is universally recommended for every American starting at age 50. So there’s already plenty of incentive to get your shots (it’s a two-dose vaccine). Lowering your risk of brain and heart disease just seems to be a great bonus, too.