I've been a recreational smoker for 5 years and I had to stop it after my 2nd concussion. Now whenever I smoke it makes me more paranoid than I already am, and gives me a headache. One of the hardest parts of recovery for me have been accepting that I can't smoke until I feel back to normal. I highly agree that it's great for stress; it was for me but now it just makes it worse. Could be different for everybody though. Also, here is an open letter from a Harvard professor to NFL stating they should combat concussions with cannabis:
http://motherboard.vice.com/read/the...-with-cannabis - he claims cannabis has obvious neuroprotective qualities