Brain problems in athletes is a long-studied, discussed and debated issue in sports and science. The latest study in the field showed that more than half of the first 21 brains donated to the Australian Sports Brain Bank by former athletes showed signs of chronic traumatic encephalopathy (CTE), a degenerative disease caused by repeated concussions.

CTE, which can only be detected when the brain is examined after death, has been linked to mental health issues ranging from mood and behavioral symptoms to cognitive impairment and dementia.

The study, which was approved by the Sydney Local Health District Ethics Review Committee (Royal Prince Alfred Hospital), reported its preliminary findings based on the first 21 completed donations up to March 26, 2021.

"All 21 donors had participated in sports with risks of repetitive head injury, including 17 who had played in football codes," the study, which was published in the Medical Journal of Australia, said.

"All but one donor exhibited some form of neurodegeneration, and 13 presented two or more neurodegenerative pathologies. The most frequent neuropathology was CTE: 12 donors had pathognomonic CTE lesions."

The paper added that six of the 12 donors with CTE, and one of nine without CTE, died by suicide.

Contact sports around the world are starting to deal with the long-term consequences of players receiving repeated head-knocks during their careers.

The National Football League in the United States set up a $1 billion fund in 2016 to compensate thousands of former players who suffered brain injuries linked to repeated concussions.

A group of former rugby players filed a class-action lawsuit against World Rugby and other governing bodies in December 2020, alleging that their failure to protect them had led to early onset of dementia.

The rugby governing body announced guidelines last year limiting full-contact training to 15 minutes per week and launched a brain health education campaign for players.