A New Zealand rugby player who had wanted his brain to be studied after suffering from the effects of multiple concussions has died aged 39, police said.

Police were called early on Wednesday morning to the Nelson home of Shane Christie, who played for the Highlanders in Super Rugby and for New Zealand Maori, where he was found dead.

Police said “the death will be referred to the coroner and we have no further information or comment we can provide”.

Christie suspected he was suffering from Chronic Traumatic Encephalopathy (CTE), a degenerative brain disorder that has been linked in the United States to a number of suicides among players in the National Football League. The NFL in 2016 acknowledged a connection between American football and CTE.

The condition can only be detected post-mortem. Christie had indicated he intended to leave his brain to researchers for study in the hope of making rugby a safer game.

“Without brain donations, we’re not going to be able to identify how long it takes to get this disease. It’s important to help the research in New Zealand,” Christie said in a recent interview.

Christie was a friend and teammate of Billy Guyton, who died of suicide in 2023 and became the first New Zealand rugby player to be diagnosed with CTE. Christie helped to establish the Billy Guyton Foundation, which attempts to foster a better understanding of the consequences of concussion.

“Bill motivated me to have the courage to speak my mind about what I see,” Christie said last year at a foundation event.

Christie reported several concussions during his playing career and, since his retirement, said he’d suffered headaches and memory lapses. CTE is known to cause mood and behavioural changes and cognitive impairment.

“It feels like a bruise in your head and when you’re walking, it hurts. So when you’re thinking it hurts, when you’re trying to exercise, the pressure hurts, and you’re not as fast and can’t think as quick,” he was quoted as saying.

CTE has been cited in a number of violent deaths involving former NFL players.

A 2023 study by the Boston University CTE Center said that of 376 brains of former NFL players, 345 of them were found to have CTE.

New Zealand Rugby said that in the wake of his playing career, Christie became passionate about coaching.

“Any time the rugby community loses a member it is felt deeply,” New Zealand Rugby said. “Shane’s passion for the game will be remembered always. Our thoughts are with Shane’s whanau (family), friends, former teammates, and community at this incredibly difficult time.”