An International Rugby Board study is part of a worldwide trend of sporting bodies increasingly monitoring the health of former players.
The issue of concussions, while not ignored during previous decades, has taken centre stage following a number of tragic deaths of former NFL players.
The catalyst for much ofthe increased scrutiny can be traced back to February 2011, when former Chicago Bear Dave Duerson committed suicide aged 50.
The former defensive back chose to shoot himself in the chest so that scientists could look for signs of chronic traumatic encephalopathy, a brain disease linked to head blows that can lead to dementia and other symptoms.
Before his death, Duerson sent a text message to his family requesting his brain be used in a Boston University School of Medicine CTE study.
Three months later neurologists confirmed that he had suffered from a neurodegenerative disease linked to concussions.
The suicides of former Atlanta Falcons player Ray Easterling and former New England Patriot Junior Seau added momentum to the debate, leading the NFL to ramp up efforts to increase player safety by pouring money into designing better equipment and changing rules to protect prone receivers.
The ripple effects can be seen permeating through the world of collision sports, meaning that shoulder charges in the NRL have gone the way of bull rush in school playgrounds.
Experts agree there should be more research into the impact of head injuries on the risk of depression and suicide, though some differ on the likely extent of the influence of head knocks.
"I think the evidence is very strong in both human and animal studies that repeated concussions that occur very close in time can result in depression and other emotional disorders that can lead to suicide," said David Hovda, a professor of neurosurgery and director of the University of California's Brain Injury Research Centre. "Whether they are the sole reason for the suicide, I don't think can be determined."
