Over the past 10 days, Dylan Cleaver has documented the stories of several men of rugby, including All Blacks, who have suffered from dementia. There will be, he reports, many more stories to tell.

Sandy McNicol will never go down as one of the great All Blacks, but he might go down as one of the most principled.

In an age when to swim against the tide in a rugby changing room was as frowned upon as crossing a picket line, McNicol declined to make himself available to play for the All Blacks against South Africa.

He and his family received threats, so McNicol instead became one of rugby's pioneers, travelling to France to play for Tarbes for three happy years.

McNicol, 71, was concussed around 20 times during his career.

Waka Nathan doesn’t just answer the door, he fills it. This, you can’t help but think, is how you want all your sporting heroes to look like when they’re 75 — upright and tall, Nathan has an undeniable presence and looks in great health On the outside, at least.

His first wife Sue, a nurse, articulated her fear for McNicol's future before she died of cancer 15 years ago.

His second wife, Sarah, is living those fears now, caught between a rock and a hard place in the home they share in Australia.

Sarah knows she will have to consider full-time care, she just hopes Sandy's comprehension decreases to the point where he won't notice the transition.

"For us, this is what passes for optimism."

Read those last eight words again. They perfectly articulate the reality of living with, and living with those who have, dementia - it strips away hope one day at a time.

Sarah's former partner, legendary rowing coach Harry Mahon, also died of cancer. "The daily grief of slowly losing Sandy to dementia is the harder to bear."

Mac Herewini.
Mac Herewini.

It would have been nice to give McNicol's story more air, just like it would have been nice to devote more time to four-test, 16-match prop Hallard White, known universally as Snow.

White is 86 now, in care on Auckland's North Shore. He was 80 when diagnosed, an age band you'd more readily associate with Alzheimer's, though his family can't help but wonder whether his dazed days contributed.

"When you play more than 190 first-class games, the chances you got concussed at some point are pretty high," said granddaughter Aisha Bower, who plays for the Waikato-Bay of Plenty Magic in the transtasman netball league. "Snow told my uncle there were so many occasions where players finished games not knowing they had just played a game."

If we could have extended the scope of the series, we might have been able to look at possible links between concussions and other regressive diseases. In that way, we could have done more to highlight the plight of those like former All Black first-five Bruce Watt, who has Parkinson's disease.

"He had concussion many times and I'm told was often the 'target' of bigger guys as he was a bit lippy," his daughter, Belinda, said. "He remembers one time being badly concussed in an All Blacks game and because there were no other players left, he was asked to go back on the field. He did not remember the whole second half. I guess it's impossible to tell but we also believe there might be a link between the head hits and Parkinson's, not just dementia."

When Belinda tried to talk to Bruce about the Taranaki Ranfurly Shield team, the one where five players have either died with or are suffering from dementia, it was too close to home - "he was of the I-don't-want-to-know variety".

The boss of Taranaki rugby says the plight of the '64 team will strike a chord with many in the province.

It's a very human response to an inhumane condition.

This is but some of the correspondence received. Mac Gardner, a semi-retired Dunedin doctor, wrote at length about the genetic qualities of dementia. He did an amazing job of making a tangled and complex subject readable.

He wrote that some of the players referenced during this series could have been genetically predisposed to dementia conditions. Ex-All Black and Wellington flanker Graham Williams has frontal lobe dementia and motor neurone disease, a medical picture classically framed by a dominant gene, C9orf72. If that was the case, it would not require extrinsic factors like head trauma to lead to the development of those conditions.

If Dr Gardner had not written in, I would have been none the wiser to cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy - a hereditary stroke disorder that can be accompanied by dementia. Will-o-the-wisp first-five Mac Herewini may have suffered this. Head trauma can exacerbate this condition, or it may have evolved at any rate.

Tony Veitch warns we'll hear a lot more dementia cases from former rugby players in the latest episode of the Vent.

"I am not at all wishing to downplay the significance of potential chronic traumatic encephalopathy (CTE) in rugby players. It is very probable that at least some of the cases of dementia, especially where of earlier onset, in rugby players who have had histories of repeated concussion, represent CTE," Dr Gardner wrote. "I applaud that you are bringing this to public attention. I am merely wishing to make the point that other causes of early onset dementia exist."

In that respect, his views echo those of Dr Jonathan Simcock, a retired neurologist who helped define dementia and Alzheimer's in a way we could all understand.

Those five Taranaki players in a single team who have succumbed to dementia could, in fact, be a statistical blip - a chance of less than one in 10,000 according to biostatistician Thomas Lumley, but a possibility nonetheless.

Through one of those quirks of fate, the NFL chose last week to finally shed the pretence and admit that there is a definitive link between American football and CTE.

Hallard White.
Hallard White.

Asked during a round-table discussion about concussions if there was a link between football and degenerative brain disorders, Jeff Miller, the NFL's health and safety policy tsar, said: "The answer to that is certainly, yes."

In a rampantly litigious society like the US, this was seen as a jaw-dropping admission from a league that once tried to dismiss such claims as quackery. However, as the New York Times reported, there might be an ulterior motive.

"Strategically, the NFL's admission makes a world of sense," the Times quoted law dean Jeffrey Standen as saying. "The league has paid a settlement to close all the claims previous to 2015. For future sufferers, the NFL has now effectively put them on notice that their decision to play professional football comes with the acknowledged risk of degenerative brain disease."

Personal damage actions are a rarity in New Zealand. In general, people who suffer personal injuries cannot sue the wrongdoer for damages in a civil court, but instead receive compensation through the Accident Compensation Corporation.

The ACC went on record with the Herald, saying the growing evidence of literature linking head trauma to long-term cognitive problems makes it likely they will be hit by claims in the future relating to dementia (though not necessarily from rugby).

New Zealand Rugby Players' Association boss Rob Nichol put it another way, saying that when they hear about ex-players struggling with cognitive issues, they "assume" concussion is the reason.

Adding to the weight of evidence, a Massey University study last year concluded that "the direct and indirect consequences of traumatic injury - not only to the head but also to other body areas, if significant - could constitute a plausible risk factor for the earlier development or faster progression of dementia".

Researcher Virginia Westerberg says her master's study completed last year highlighted the risks of early onset dementia from traumatic head injuries such as concussion, particularly through contact sports.

Concerned by the growing trauma statistics in New Zealand and dearth of research into the consequences, she designed a large-scale study in collaboration with Palmerston North Hospital involving a database of nearly 7000 cases.

"The results showed that a history of traumatic injury was more frequently found in cases with dementia than in the controls," Westerberg said.

She found just over 73 per cent of people with dementia had had a traumatic injury significant enough to require admission in the emergency department. Only 26 per cent of the non-dementia controls had a history of trauma. The data didn't specify whether the injuries were caused by falls, blows, accidents or sport injury.

New Zealand Rugby have not yet been convinced enough to be so definitive. When asked about the cases of dementia among ex-All Blacks, chief executive Steve Tew offered this: "It is a complicated issue and even the highly skilled and trained medical professionals cannot give you a definitive answer on a whole load of really important questions."

Sceptics would doubt that rugby chiefs really want definitive answers. Ask Rob Allen, the brother of All Black first-five Nicky who died after suffering a traumatic head injury while playing a club game in Australia, and he'll tell you that NZR would never want to highlight the true long-term risks because parents would suddenly start pulling their kids out of the sport.

Waka Nathan.
Waka Nathan.

It is much easier to write things off, like Tew did, as complicated.

But we're talking about it now, which is a start. Thanks to people like Neil Wolfe and Waka Nathan who are in the midst of their dementia journeys, and the families of many others such as McNicol and White, we can have a national conversation about this most sensitive of subjects.

But for that conversation to go to the next level, we need someone in rugby to say: "This is the reality, if you suffer traumatic head injuries in rugby, or multiple mild traumatic injuries, you increase your chances of long-term brain disorders."

It's a leap, but one worth taking.