New research shows rugby players who experience concussion face more cognitive difficulties when they retire from competitive sport.

Research by AUT and New Zealand Rugby, sponsored by World Rugby, has found long-term differences in thinking between former rugby players and non-contact-sport players.

The study, published in Sports Medicine, involved 366 former New Zealand athletes from elite rugby, from community rugby and from cricket and hockey.

Players with a history of concussion performed worse in cognitive flexibility, complex attention and executive function.

Rugby players experienced more concussions and performed worse than non-rugby players.

Researcher Alice Theadom told Mike Hosking elite rugby players are more likely to suffer from cognitive problem later in life.

"The elite athletes also had more difficulties in terms of processing information and complex attention tasks, where you have to hold information in your head while also working on it."

Theadom said this means ex-players could find it difficult to cope with distractions or make quick decisions.