New Zealand Rugby (NZR) says the science around brain disease in players is "complex and evolving".
A study by researchers from Glasgow University and Queen Elizabeth University Hospital found elite rugby players were more than two times more likely to have dementia, and up to 15 times more likely to suffer motor neurone disease than other people.
NZR's general manager professional rugby, Chris Lendrum, told Checkpoint the study added to understanding about the potential risks of contact sports, but further research was required.
"Obviously those numbers are distressing and will provoke concern amongst people ... We need time for people in our research and scientific community to look at [the study] and assess the overall validity of it."
Lendrum said NZR's approach was to prioritise player welfare and many initiatives were underway to attempt to make the game safer to play.
"We are trying to balance what we believe are the considerable benefits of playing rugby - mentally, physically, socially - with responding to science and risks appropriately."
He said while there was a lot of research that pointed to "challenges for all contact sports" with regard to the risk of degenerative brain diseases, the science was "incomplete".
"I think we're assuming that there's a risk ... rugby's working on a conservative basis that there is a link," Lendrum said.
"We're doing everything that we can at the moment, based on what we know."
He wasn't able to say how many of the organisation's former players had what could be termed a degenerative brain disease, but said NZR was waiting on the final results of a study looking at the long-term health outcomes of 12,000 former professional rugby players, which it had helped fund.
"At the professional level obviously we employ all our players and so we have medical oversight of our players," he said.
"I think we're doing everything we can in management and aftercare of our employees here, and obviously we're also trying to look at law variations in the community game that have the potential to make the game safer."
Lendrum said a "significant amount" of research into the issue was underway, either commissioned through New Zealand Rugby or co-commissioned with world rugby, at both professional and community level.
"The question, essentially, is are we doing everything we can right now based on what we know? And I believe and New Zealand Rugby believes that we are."
