New research shows a link between boxing and early onset dementia in Polynesian men.
Doctors at Auckland's Middlemore Hospital noticed a spike in men of a similar age turning up with symptoms of the brain disease, then discovered they had all been boxers.
A legendary kickboxing match from 2001 shows the pride some fighters have at being able to take a punch, with Kiwis Mark Hunt and Ray Sefo daring one another to take a head shot. But it's this sort of punching that doctors at Middlemore suspect is the cause of early onset dementia.
"We started to notice that there was this history that kept popping up of people that, one, had memory loss, or, two, had cognitive problems," says Dr Susan Yates.
"They were all of Pacific Island ethnicity - and there was a strong sort of boxing history."
The eight Polynesian men with memory loss had been a mix of amateur and professional boxers. They all started showing signs of dementia between the age of 47 and 71, and half of them were under 55 - much younger than the disease usually appears.
One of New Zealand's top boxing referees, David Craig, admits some fighters think they're too tough for their own good.
"That creates a problem. The number of times I'll stop a fight and you'll get that protest from the fighter saying, 'I'm okay.'"
But the sport is now taking notice of the growing body of research about the risk of head injuries, and Mr Craig says they're now stopping fights earlier.
"I don't want anybody tapping me on the shoulder in 10 or 20 years' time and saying, 'Hey you reffed my dad and he's a vegetable now,'" he says.
Professional heavyweight boxer Junior Fa says the key to staying safe is the right technique - like rolling with the punches.
"Since it's coming in this direction I'm going that way too, so I'm not just standing there taking a big, big punch," he says.
Boxers know the risk when they get into the sport, but it seems the reality doesn't fully hit until they're out.