NRL legend Paul Green had an advanced brain disease at the time of his death, doctors have revealed.

Green, who was found dead at his home in Brisbane on August 11, had been suffering from an advanced form of CTE (chronic traumatic encephalopathy).

CTE is a neurodegenerative disease that can affect athletes who endure repeated concussions and head knocks during their careers in contact sports such as rugby league, combat sports and American football.

His widow Amanda has made the decision to donate the 49-year-old's brain.

Ms Green said the diagnosis has given her daughter Emerson, 13, and son Jed, 10, some "peace" and "relief".

"I was able to sit Jed down and explain: 'Daddy's brain was sick, that's why he did what he did,'" Ms Green said.

She was able to give Emerson an explanation that makes more sense than what was being repeated – that he took his life because of depression.

"She now understands that he wasn't in that space and there's nothing we could have done, because he was sick."

Paul and Amanda Green together in 2017. Photo / Getty

Green had a decorated career as a player, stepping onto an NRL field more than 150 times for a host of clubs including Cronulla, North Queensland and the Roosters. A clever halfback, Green played 95 games for the Sharks and was at the Roosters when they won the 2002 premiership.

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The footy legend also played seven State of Origin matches for Queensland, as well as three additional matches for the Maroons during the Super League war.

Green finished his NRL career at the Broncos in 2004 before turning his hand to coaching. His greatest achievement was leading the Cowboys to their maiden premiership in 2015, when they defeated Brisbane in one of the most thrilling grand finals in history.

Green also coached Queensland's State of Origin team in 2021, when they lost the series to NSW 2-1.

After seven years in charge of North Queensland, he was replaced by Todd Payten at the end of 2020. Green's name had been thrown about as a potential mentor for a number of NRL sides who have parted ways with their coaches this year, including the Wests Tigers, Bulldogs and Warriors.