The Herald has discovered a cluster of dementia cases among the successful Taranaki shield side of 1964.
The odds of that occurring could be as high as three in 100,000, which medical experts believe adds to growing anecdotal evidence that multiple concussions suffered in rugby can lead to serious brain diseases later in life.
There have been no claims lodged with the Accident Compensation Corporation, but a spokeswoman acknowledged that with greater understanding and awareness of the dangers of concussion it is likely "that we will in the future".
The Herald has spoken to families of four players affected by dementia, mainly Alzheimer's. We have also identified at least one other player of that era afflicted by the disease but do not have permission to identify him.
All the named players suffered serious concussions during their playing days, with Neil Wolfe admitting he only "woke up" during halftime of his debut test against France at Eden Park in 1961, after being knocked out in a late "coat-hanger tackle" after 20 minutes.
That was one of three serious concussions he endured during his fleet-footed career.
I have a little bit of dementia now and I suppose [the dementia] relates back to the time I played rugby and was in fact knocked out.
The other players in that Taranaki backline who have died or are dying with dementia are Ross Brown, arguably Taranaki's greatest player, who passed away after a long battle with Alzheimer's in 2014; Bob O'Dowda who is now in permanent care in New Plymouth; and Kerry Hurley, who is cared for in a home in Christchurch.
The link between dementia and head trauma like that suffered by rugby players is a potential powderkeg for rugby administrators.
Recent studies, particularly in the United States, have established persuasive links between repeated head trauma, such as concussion and the early onset of cognitive issues such Chronic Traumatic Encephalopathy (CTE), which was once known as being punch drunk.
A recent study of retired French rugby players reported a "significantly greater number of concussions and recurrent concussions than other retired sportsmen". It also found that retired rugby players with recurrent concussions were more likely to suffer from major depressive disorders.
However, a 2015 Auckland University of Technology study, carried out in conjunction with New Zealand and World Rugby, concluded that ex-sportsmen, irrespective of concussions incurred, suffered no negative occurrences beyond the norm in terms of marital status, mental health issues or brain-cell efficiency. There were findings that ex-sportsmen with four or more concussions performed worse in some neuropsychological and balance tests, but those findings were not definitive.
In terms of the 'Taranaki curse', Professor Thomas Lumley, a biostatistician at Auckland University, said the chances of five players in a single team developing the condition before age 70 was about 3 in 100,000. The chances of dementia increased the more elderly the players became.
The difficulty is in differentiating between when the men started showing symptoms of dementia and when they were officially diagnosed. "You could find dementia/Alzheimer's in four or five players in the same team of this age just by bad luck, but the chance is low enough to reinforce existing concerns about the effects of concussion in rugby," Lumley said.
Jan O'Dowda, the wife of Bob, said her husband's diagnosis was difficult to deal with, as was his precipitous decline. The more people she talked to, the more startling the information was.
"I was trying to establish why he would have got dementia at such a young age and why it would have developed so rapidly," she said. "Some of his mates told he took some serious head knocks quite early in his playing career."
Since then, O'Dowda has been left astonished by how many times her husband's story is mirrored by former teammates.
It's almost like an epidemic.
There is the unpalatable prospect that what is happening in Taranaki now is happening elsewhere, and many believe it could get worse before it gets better.
Rugby turned professional in 1996 but the sport's rulers did not start getting smart about concussion until about five years ago. Even now New Zealand Rugby Players' Association chief Rob Nichol says there is too big a discrepancy between various rugby environments in their attitude towards concussion.
"For the past four or five years, we've just assumed there is a connection," Nichol said. "Our starting point is if there is brain trauma and it's not correctly managed, there will be complications later in life. We don't need a scientist or anyone to tell us that; we're just assuming it.
"We're pushing as hard as we can to make sure we're at the forefront globally in concussion management."
We asked Dr Jonathan Simcock, medical adviser to the Neurological Foundation, to guide us through the dementia/Alzheimer's disease minefield. These were the key points.
• Dementia is an umbrella term for the impaired ability to think. Common impairments include memory, language, judgement and behaviour.
• Dementia is not a "normal" part of ageing. It is a syndrome; a brain illness.
• It is a syndrome that interferes with social or occupational functioning.
• Alzheimer's is, by some distance, the most common form of the syndrome, accounting for more than a third of dementia cases. Other common forms are vascular dementia (18 per cent of cases), which is often associated with strokes, and frontotemporal dementia (12 per cent), which typically occurs in younger patients.
• The most striking feature of the pathology of Alzheimer's is amyloid, protein fragments that become insoluble and create folds. These folds affect the neurons and blood vessels, causing plaques and tangles to form.
• Another feature of dementia syndromes is an abnormality of tau protein in the brain. This could be a feature of amyloid but it could also be a distinct feature. Those seeking treatments for dementia are increasingly looking to target tau directly.
• The cause of Alzheimer's is not known, although there is almost certainly a genetic disposition.
• The risk factors for Alzheimer's disease are identified as cardiovascular (including smoking, heart and lung disease, obesity, diabetes and hypertension), head trauma and susceptibility genes.
• Trials for cures "have provided no consistent evidence for efficacy for any specific intervention".
• Despite this, a cure for dementia could be found within five years, the leader of the global council on the disease said recently. Dr Dennis Gillings, outgoing chairman of the World Dementia Council, said recent scientific progress had surpassed his expectations and was optimistic that treatments that could remove the plaques in the brain linked with dementia, and those to unscramble the neural tangles that characterise the disease, might be developed as soon as 2020.
• Dementia places a high strain on caregivers. "You're stuck with it," says Simcock. "The patient may change over time but they do not get any better."
• Approximately 47.5 million people suffer from dementia worldwide. That is expected to increase to 75.6m by 2030.
• The economic impact of dementia is estimated at US$604 billion.
Additional source: World Alzheimer Report (2010)