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In the few weeks since Ambrosie took the job atop the CFL, evidence has continued to tumble forth about the risks associated with playing football. On a small scale, a Toronto hospital that studied the brain of former CFL player Rick Klassen found that it showed signs of CTE, and also signs of a form of dementia. And on a much larger scale, a Boston University study of the brains of former football players detected defining features of CTE in an overwhelming number of subjects: 99 per cent of players with National Football League experience; 87 per cent of a much smaller subgroup of former CFL players.

Photo by Frank Gunn / CP

Neither of those developments were necessarily unexpected. In the case of Klassen, he had shown symptoms associated with CTE — anger, irritability — in the years before his cancer-related death in 2016. It is very often the case that when someone suspects they have CTE while alive, a post-mortem examination of their brain confirms the suspicion. (This is, notably, not always the case.) And with respect to the large Boston University study of more than 200 brains, the findings were in line with previous studies of brains after death, which tend to discover a prevalence of CTE pathology in at least 95 per cent of the brains of former NFL players.

After the study was released, the CFL said in a statement many questions “remain unanswered” and player health safety remains an “important priority.”

Huge parts of the CTE puzzle do remain unsolved. How does the rate of CTE characteristics in the brains of former football players compare with the rate in the wider population? And how many of those people, football-playing or otherwise, with the telltale CTE proteins in their brains, outwardly suffer from the symptoms like depression, memory loss and anger that have been seen in so many high-profile cases, like Mike Webster and Junior Seau? Put another way, is there a population of people whose brains show signs of CTE but who do not seem particularly harmed by it? Because post-mortem tests are the only avenue available, researchers have no means to compare the football-playing group with a control group.