Conrad Smith of the Hurricanes holds his head after returning from a concussion test.© Hagen Hopkins/Getty Images

A major study of rugby union players points to a possible connection between frequent concussion and brain function, the project's lead researcher said on Tuesday.

The long-term study - the largest of its type to focus purely on rugby union - released its preliminary findings and researcher Patria Hume wants players to become more aware of the risks.

"If you have a concussion you need to report it and get it medically assessed," Professor Hume told AFP. "You also need to consider that potentially there may be some long-term health effects. Ninety four percent of elite level rugby players experienced one or more concussions, that's a lot."

The Auckland Univeristy of Technology study was commissioned by World Rugby in 2012 due to growing fears about the potential for long-term brain injuries in high impact sports.

It examined the health of 485 men, with 131 of these falling into the category of former professional rugby players while a further 281 amateur rugby players were also included. Athletes from non-contact sports made up the remaining 73 places.

Hume said the study, which is in the process of being peer reviewed for publication, showed a statistically significant link between repeated concussion and brain damage.

"We've got to go through that scientific process, but what I'm saying is that, as a scientist, it's irresponsible for people to say there are no long-term brain health issues," she said.

"Because all indications so far from the analysis we have done indicates that there possibly are for the rugby players and for people who have been concussed more than four times."

She said rugby players who have suffered four or more cases of concussion performed far worse in tests measuring mental and physical coordination, motor speed and multi-tasking.

World Rugby chief executive Brett Gosper described player welfare as his number one priority, saying he wanted more research into preventing and managing concussion.

"While the study does not provide any definitive conclusions, we are alive to all potential risks and, as such, we will continue to prioritise research in this very important area," he said.

Hume said there had been a cultural change in rugby in recent years recognising the dangers of concussion. High-profile players such as All Blacks Richie McCaw, Kieran Read and Brodie Retallick have all sat out matches in the past 12 months after suffering concussion.

However, problems still exist, with an outcry in Britain in February when Wales wing George North was twice knocked unconscious during a Six Nations defeat to England.

Similarly, French rugby bosses tightened concussion rules last year after Toulouse centre Florian Fritz was sent back out to play even though he was bleeding and clearly disorientated after