Can a concussion cause personality changes that are permanent?

Yea I'm 14 and I just got a severe concussion and I do the SAME thing and if my friends or parents wouldn't tell me I wouldn't know I did it!! Just try to support him because concussion are hard on anybody and we DONT try to do it we just do our brains got messed up in the concussion process ( the brain hitting the skull and then the brain swelling ) so try to be reasonable with him and support him the best you can remember we DONT try to get mad!! Good luck!!!