Closer to home, former All Blacks Paul Tito and Steve Devine have spoken out about their on-going health problems after suffering multiple head knocks during their careers, which were documented in last year's Herald series The Knock-On Effect.
But rugby bosses have so far been reluctant to acknowledge any link between concussion and long-term cognitive impairment, pointing to the need for more research to be done.
The New Zealand Rugby Union and the International Rugby Board last year enlisted AUT's sports performance research institute to lead the study - the results of which were to be released in November - but they are struggling to get participants, leaving the research team desperately short of data.
"The IRB and NZ Rugby are just so keen to try and help prevent injuries and look after their players. That's why we need people to participate in this study, so these organisations can do the best they can," said Hume, one of the study's lead investigators.
Researchers need to recruit 200 ex-elite rugby players and 200 former community rugby players for the study, which requires participants to undergo a series of medical and online tests.
The original plan was their results would then be compared with those of 200 former cricketers, but with only 22 having signed up so far, Hume said the latter group has now been extended to include hockey players.
But although they are "desperately low" on former cricket and hockey players, they are still well short of their targets in all the categories.
Of the 426 people who have signed up to do the general health questionnaire online, only 137 have completed it - 99 of those being former community rugby players.
Hume said the AUT research team had been surprised by the lack of response.
"The IRB wanted us to do the study because New Zealand is rugby mad. If we can't do the study here, where in the world are we going to do the study?"
She believes one of the difficulties is your typical Kiwi bloke does not like discussing health issues or undergoing medical tests.
"There seems to be awareness of the study, but we've had trouble getting people to contribute," she said.
"Someone said to me 'I really don't want to know how my health is', which is fine, they don't have to know the results if they don't want them. Just fill in the questionnaire so that we know them," she said.
Although the long-term effect of concussion is topical, the AUT study, fronted by All Black great Buck Shelford, will look at all health outcomes of playing rugby.
AUT Rugby Health study
Who are they looking for?
Male retired rugby players from the following groups:
• All Blacks, Investec Super Rugby, ITM Cup, NPC, etc, players aged between 30 and 60.
• Club rugby players of any level aged between 30 and 60.
• People who were involved in the Rugby Injury Prevention and Performance (RIPP) study in Dunedin in 1993. Also:
• Former cricket and hockey players (male only) of any level currently aged between 30 and 60.
More information