The father of two underwent emergency surgery and was placed in an induced coma, but died three days later.
Meanwhile, a 17-year-old rugby player remains in an induced coma after suffering a head injury on Saturday during a high school match in Dunedin.
Brain injury specialist Willie Stewart told BBC Radio Scotland the brains of head injury victims looked similar through a microscope to people with dementia.
The neuropathologist examined the brain tissue of a former rugby player for abnormal proteins associated with head injuries and dementia, confirming what he believed to be the first confirmed case of early-onset dementia caused by playing rugby.
Dr Stewart said sports such as rugby and American football were beginning to lead to problems later in life normally suffered by former boxers.
Dementia pugilistica is also known as punch-drunk syndrome. Symptoms - which include memory and speech problems, trembling and lack of co-ordination - usually appear 12-16 years after the boxer's career begins, and 15-20 per cent of professional boxers are thought to develop it.
Mr Hargood said in terms of rugby, concussions and head injuries were almost always the result of bad technique.
The RugbySmart Programme, developed by the NZRU and ACC, was an "excellent" safety programme for coaches.
None of the 160 coaches in the Wairarapa were allowed to coach a team unless they'd done the programme, and the next step should be to make it compulsory for players.
The number of rugby-related injuries had dropped "dramatically" since the programme was introduced in 2001, he said.
"I'm not a medical expert but what I do know is that good coaching, good techniques and education reduces the likelihood of serious injuries."
Mouthguards played an important role of cushioning the brain from shock waves but headgear was almost completely ineffective, he said.
ACC received 539 Wairarapa claims for rugby-related injuries last year at a total cost of $540,000 - 16 fewer claims than 2011.
National Dementia Co-operative chairwoman Chris Perkins said the impacts of boxers' head injuries were well documented, but the same principle could apply to other high impact sports such as rugby.
"It's one of the known facts that if you get too many head injuries, you end up with dementia," she said.
"Apart from the fact it's a brain injury, it leaves you with less brain reserve." APNZ
