Former Chicago Bears quarterback Jim McMahon calls himself “old school,” including his use of marijuana both during and after his career.

Yet McMahon’s stab at self-medicating could be ahead of its time. Researchers at Johns Hopkins plan to test whether a compound found in hemp — and its notorious cousin, cannabis — proves as effective in treating brain injuries as testimonials claim.

Some former players believe cannabidiol, or CBD, could help millions who suffer brain injuries each year, including chronic traumatic encephalopathy, a degenerative disease caused by repeated concussions and found in many former NFL players whose brains have been autopsied.

“I don’t think any of us regret what we did,” said Jake Plummer, who played 10 seasons before retiring in 2007. “But there’s no question it comes at a real cost.” [Read more at the New York Daily News]