Stand by this weekend for another huge collision between New Zealand and England. Note the deliberate use of the word “collision”. Every modern Test demands such shuddering levels of commitment that “game” feels inadequate. Eden Park will be no place for pacifists and none of the gladiators in black or white will be considering the possible longer-term effects of their brutal trade.

Just over two miles across town at the University of Auckland, however, they are busy doing it for them. “The dream for a neuroscientist is that people hold on to their faculties for the entirety of their lives,” says Maurice Curtis, professor of neuroscience and deputy director of New Zealand’s Human Brain Bank, which is researching the effects of head impacts in sport. “We want their brain health to be optimised every step of the way.”

Across the cafe table sits Dr Helen Murray, another prominent expert in the same field and a top-level sportsperson herself. Her “other” life playing on the left wing for the Ice Fernz, New Zealand’s women’s ice hockey team, makes her uniquely qualified to discuss the pros and cons of contact sport. “You don’t need to get to the end looking pretty,” she tells the Breakdown. “But we want to make sure you get to the end with a high quality of life.”

Not everyone, sadly, has that luxury. Last year New Zealand rugby was rocked by the death, aged 33, of Billy Guyton, the former Tasman and Māori All Black half-back. He had been suffering from the after-effects of repeated concussions and was the first professional rugby player in New Zealand to be publicly diagnosed with confirmed chronic traumatic encephalopathy (CTE) after his death. His family, who had witnessed his anxiety, depression and increasing mental confusion, donated his brain to the Brain Bank to try to assist others.

His tragic case is part of a rising tide of concerning stories. Murray says she receives at least one email per week from people who believe they may have CTE. “We know more people are out there but they haven’t had the official diagnosis,” she says. In New Zealand alone there are already about 40 former rugby players in that category, with at least another 200 in Australia.

The experts will also tell you that it goes well beyond those who played top-level rugby. “When we started we thought we might get one case a year,” says Curtis, who now receives a couple of brain donation offers per week. “We’re generally dealing with people who played rugby many years ago or did so more recently and have had an early demise. But actually CTE is also evident in people who played long-term school and club rugby.” Many have yet to go public. As Curtis says: “The ones who don’t make the headlines are the ones that suffer in silence.”

None of this, self-evidently, is what rugby wants to hear. The continuing court action in the UK involving hundreds of former players is concentrating minds globally, but liaising with the families of those affected, such as the Guytons, is what is really driving the neuroscientists at the sharp end in Auckland. “I was particularly moved when Billy’s dad was asked if he would let his younger son, who is about 10, play rugby,” says Curtis. “And he just said no. I guess he just hasn’t seen enough change in the game.”

He also quotes the recent newspaper article in New Zealand written by Geoff Cooper, whose father – also called Geoff – adored rugby and played it for more than half a century. Ultimately it did not love him back. “My father didn’t intend to die doing what he loved,” wrote his son. “Fifty-seven years of playing rugby gave Geoffrey Joseph Cooper friends and fitness. But it also gave him chronic traumatic encephalopathy.”

Which adds even more weight to the work being done both in Auckland and internationally. Might, for example, certain treatments for Alzheimer’s prove even more effective in the treatment of CTE? The holy grail is a brain scan or a bio-marker – ideally a simple blood test – that can detect the danger signs early. “For us it’s about how we give people a diagnosis that tells them what is actually going on,” says Murray.

“How do we take the knowledge we have from the brain tissue and translate that into something that’s measurable and says you have this or that condition?” A breakthrough may soon be forthcoming. “The Americans will tell you within five years,” continues Murray. “They’ve started big bio-marker blood studies in the last year. But you never know.”

In Auckland, in an ideal world, they would like to recruit a cohort of people who have CTE symptoms and monitor them over a longer period. If the Brain Bank could attract just $NZ1m (£475,000) in annual funding – whether from government, sporting bodies or private individuals – Curtis believes it would “make a huge difference” to a lot of people. “There are a number of parts of the rock face being worked on but this is cutting edge research, for sure. [But] it currently seems to be under funded across the board. It’s politically challenging and, in a way, it’s easier to study more complex diseases. If you’re a funder you probably go: ‘Just stop the rugby.’”

There are some tiny glimmers of light out there, however. Better head injury management, reduced contact in training and scientific advances can all help to some degree. “It may be that we get to the point where we know that above a certain point is definitely the danger zone,” says Curtis. “Until that comes down you’re not back on the field. That would also give the opportunity to offer a supportive medication or a nutrient mix that helps the brain.”

Murray is also interesting on the subject of both ice hockey – “Hockey has this reputation for being incredibly rough but we don’t start contact until the age of 15” – and women’s rugby. “There’s no reason to think women aren’t going to get CTE. We’re already seeing it.” She also cites the extensive research in the United States which found the length of a player’s career was particularly significant. “What’s important is exposure to head injuries. So not necessarily the number of concussions but all those sub concussive head knocks. If you’re playing rugby for 40 years, that’s probably your main source of them.”

Did you know, in addition, that it is not the straight-on front or back impacts that inflict most damage on the brain but the stretching and twisting caused by hits absorbed at a 45 degree angle? Or that research into deaths among military personnel in the United States has linked bomb blast exposure to increasing rates of dementia or suicide? Or that it takes two months of intensive analysis and double checking before CTE can be formally diagnosed in one deceased person’s brain?

Equally, though, rugby still has the same in-built problem as every other contact sport. “I love my sport,” says Murray. “I wouldn’t take any of it away. But at the same time you do worry. You say: ‘What can we do to make this safer?’ I think every sport is going to have to look at it. Do we need a shorter season? How are we going to reduce the risk where we can? It’s not brain surgery to say that hitting your head a lot is not necessarily good for you. You don’t want to scare people but it is a big issue. We can make actions now that are going to have positive effects in multiple ways.”

Quite so. Which is why Curtis believes administrators awaiting the outcome of the landmark UK court action could be more proactive. “We think a pre-emptive approach would be the prudent one. We know many people are being affected by this. We can make changes now knowing what we know about head injury exposure and accelerate the science. I don’t think it has to be one or the other.” Good luck to New Zealand and England this Saturday but modern rugby continues to wrestle with far bigger issues.

• This is an extract taken from our weekly rugby union email, the Breakdown. To sign up, just visit this page and follow the instructions.