Former Newcastle Knights winger James McManus figures he took at least 25 over his career. His wife Eshia estimates double that.

But what neither was prepared for was for him to sustain dementia leaving him with the brain of a 50-year-old by the age of 30, thanks to repeated blows to the head.

McManus made all of his 166 NRL appearances for the Knights in a career that also included three Origin games.

Towards the end of his career McManus, now 36, was plagued by headaches, anxiety, depression and feelings of uncontrollable rage. Relatively minor knocks, which he would previously have shaken off, were putting him in hospital with concussion.

"I was spiralling ... There was a period of time when life was genuinely falling apart," he said. "I'd have these rages that I couldn't control. I was doing things on impulse - one day I just bought a car.

"I had a constant headache, so I'd have a couple of drinks to try to settle the pain down, which wasn't healthy.

"But when I spoke to the doctor, they thought it was a mental health problem and I was referred to a psychologist instead of a neurologist."

It was Eshia who pushed for a different diagnosis.

"His personality had changed too but I didn't know what was causing it," she said. "I just knew he was a very different person from the one I met and married. I thought he was being a bit of a jerk and it really was a tough time for our relationship."

McManus was diagnosed with chronic traumatic encephalopathy (CTE), a form of dementia related to repeated head injuries.

His claim against the Knights' handling of his concussions in the NSW Supreme Court ended without compensation in September, with the case resolved in the club's favour. A number of prominent Knights players and officials were among those who may have been required to give evidence.

McManus is one of thousands of people across Australia suffering from CTE, ranging from those who play contact and combat sports, to members of the military and domestic violence survivors.

Symptoms include mood disturbance with depression and anxiety, behavioural disturbance with a tendency towards impulsivity and anger, changes in personality, impaired judgment, confusion and cognitive decline.

Macquarie University's Concussion Connect service has launched a new biobank it hopes will make early detection of CTE easier.

The Australian CTE Biobank and its equivalent in New Zealand will collect samples and data from patients who have suffered repeated brain injuries and repeat this every 12 months to track progression of the disease, says neurologist Dr Rowena Mobbs. The aim is to develop specific biomarkers for CTE, so it can be detected and treated early.

"Make no mistake - this disease shatters lives," Dr Mobbs said.

McManus and his wife are ambassadors for the CTE Biobank and say they're keen to do anything they can to help people combat or prevent this degenerative disease.

"I loved football, absolutely loved it," he said.

"But had I known it was going to lead to this, I wouldn't have played it. Not to the extent that I did."