YES! Adding ganja or any other substance to a person recovering from a brain injury is problematic. The person could be more prone to sedation, confusion, disorientation, disorganized thinking, and misperceptions including hallucinations. It's also hard to know all the adulterations a given supply of ganja might contain -- including possible pesticides, for which no one is testing. Not healthy.
Could slow recovery. Mj would usually worsen any cognitive effects that the brain injury alreasy has like slowed thinking and memory loss. It could also possibly further damage already damaged brain tissue...The ultimate answer is...Don't do mj with a brain injury.
Please re-think it. It just isn't a good idea to expose an already damaged brain to more potential injury from recreational drug use. In my experience, keeping in mind that tbis vary enormously, patients with tbi are prone to unpredictable reactions to both recreational and prescription drugs. I tell my patients with tbi "all bets are off" when it comes to predicting reactions and side effects of drugs and alcohol.
I forget? Don't need to be a scientist to knwo cannabis (thc) impairs memory - even avid pot-smokers cheech & chong have immortalized a track about it on their up in smoke album. Studies show interference with verbal memory and learning, reaction times etc, and thc can be found in brains of heavy smokers 6 months after stopping. Probably not permanent, but it takes months to clear up - seen it in patients.