An autopsy on Rick Klassen's brain, which he donated to the Canadian Concussion Centre reveals he had severe CTE, as well as a form of dementia called argyrophilic grain disease (AGD).

The brain autopsy of Rick Klassen shows the former CFL lineman had stage II levels of chronic traumatic encephalopathy (CTE) in combination with dementia. "The extent of the CTE was a little bit surprising to be honest, the fact that talking to Dr. Hazrati that my dad was among the worst cases that she studied," said son Chad Klassen.
The finding of CTE in combination with a type of dementia known as argyrophilic grain disease (AGD) has never been seen before. ...
"AGD is not usually seen in patients that young," she said. "Does it have anything to do with concussions? We can't say."
Chad Klassen said his father reported suffering three major concussions in his playing career, but thousands of micro concussions as a result of playing a position that required hitting on every play. ...

According to Dr. Hazrati, the rate of CTE is higher is in the brains of people who have played contact sports versus those who haven't.
"The reason we link these two things is because it's been reported in boxers, hockey and football players. It is assumed that because they have suffered a lot of blows to their head, that is what is causing the CTE."
Recently departed CFL commissioner Jeffrey Orridge refused to acknowledge a link between football concussions and CTE, but Klassen hopes the results of his father's autopsy will help push the league to take the issue more seriously.


http://www.cbc.ca/news/canada/british-columbia/former-cfl-star-rick-klassen-s-brain-autopsy-reveals-extensive-trauma-1.4192736