Leigh Adams knew something was wrong earlier this year when he occasionally struggled to remember people's names, where he had put his keys or why he had walked into a room.
He was also prone to debilitating headaches that lasted for days, had little to no energy and, most concerningly, had an unusually short temper.
Adams' ordeal began when he was concussed in North Melbourne's round 23 win over Melbourne at the end of last season.
The side-effects of that concussion lingered long enough that Adams saw a neurologist and was ruled out of North's three-week finals campaign.
Adams already had a history of concussions – his most recent one having come less than three months earlier when he was driven to the ground in a strong tackle by Richmond's Troy Chaplin – and the neurologist wanted to monitor him closely, concerned by his slow recovery.
Six months later, Adams suffered another concussion just 10 minutes into his second game of the 2015 pre-season.
He was playing for North's VFL affiliate Werribee in a practice match against Footscray. It would be another 10 weeks before he felt like himself again.
"That's when it was starting to get a bit of a worrying trend towards obviously some long-term damage," Adams said.
"It was more frustrating than anything. The specialists told me it was definitely going to get better, but early on I couldn't really see it getting better because I was in a bit of a fog.
"A lot of blokes do get those concussion symptoms for a week, maybe two if they've had a severe concussion - but I was having them for eight to 10 weeks, which is obviously not a great sign.
"The specialists just kept reiterating, 'It's going to get better, it's just a matter of time'.
"I think that really helped, knowing they were saying I was going to come out of it."
Despite his concerns, Adams wanted one last shot at resuming his AFL career. At 27, he did not want to retire before his time.
He returned in the VFL in late May and showed no signs of rust, racking up 28 possessions for Werribee in three-and-a-half quarters against Sandringham.
But in his third game back, Adams was again concussed after copping a head knock against Collingwood's VFL team.
It would be another six weeks before he officially retired. In that time, he continued to be closely monitored by his neurologist, with North keen for the side-effects of his latest concussion to pass before he made any decision on his future.
But Adams knew almost as soon as he came off the ground that June afternoon that his football career was over.
"After I got that minor hit to the head (against Collingwood's VFL team) and was suffering those concussion symptoms I knew it was probably time to retire," he said.