Swimming in cold water could help protect the brain against degenerative diseases, according to research in England.
Research suggests a dip in the cold can trigger the production of a protein that might protect the brain against such diseases, like Alzheimer's.
Almost 70,000 New Zealanders have dementia and that number is expected to almost triple by 2050, according to Alzheimers New Zealand.
The answer to why cold water makes a difference is a latent hibernation ability prompted by getting cold that it seems human beings retain.
When animals hibernate they lose some of the connections between their brain cells but they are miraculously reformed when they wake in the spring thanks in part to a protein discovered by a team at Cambridge University.
So scientists wanted to know if humans produced the same protein.
It's not for the faint-hearted, but they used a group of people to regularly get cold for three years of winter blood tests.
"We compared you to a bunch of people doing Tai Chi who didn't get cold and none of them get increased levels of this protein, but many of you did," Cambridge University dementia research professor Giovanna Mallucci told the group, huddled by a chilly poolside.
"It tells us that cold does induce this protein in humans. You are the first, sort of, non-patient cohort to show that cold water swimming raises this protective protein, which is pretty cool."
However, winter swimming can be dangerous if people aren't used to it or have an underlying illness.
The challenge for researchers now is to instead find a drug that stimulates the production of the protein in humans and to prove it really does help dementia.
Mallucci said if the progress of dementia was slowed by even a couple of years on a whole population, though, that it would have an enormous impact both economically and health-wise.