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VACCINATIONS might have an unexpected bonus. They may dramatically reduce
your chances of developing Alzheimer’s in old age.

According to René Verreault from Laval University in Quebec, his study
of ageing seems to show just that. Verreault’s team looked at data from 4392
elderly people in a five-year study and correlated the incidence of Alzheimer’s
with a variety of factors—including whether they had been vaccinated
against various diseases.

To their surprise, they found that people who’d had a tetanus or diphtheria
jab were 59 per cent less likely to be diagnosed with Alzheimer’s during the
study. Polio jabs led to a 40 per cent reduction in risk, and even flu shots
seemed to have a mild effect.

Verreault cautions that they only had very crude information about
vaccinations from a questionnaire, and the study wasn’t designed to look at this
specific effect. “It’s very preliminary, but it’s intriguing,” he says. If the
correlation turns out to be more than a statistical fluke, there could be two
explanations. Either boosting the immune system affects the brain’s ability to
fight amyloid plaques, or defeating childhood illness might have a knock-on
effect that leads to better mental health in old age. Either way, Verreault has
no idea what the mechanism might be.

For now he’s simply happy that they didn’t find the opposite
effect—more vaccinations correlating with a higher incidence of
Alzheimer’s. He hopes that someone else will now look at the link more closely.