Brain injury and diet

My son is 18 now he was in a motorcycle accident with his dad when he was 10. I wondered if there is any kind of diet out there that could help him to control his anger, deppression, and his tiredness. He also still has some break thru seizures. The doctors just tell me theydon't know why he is so tired, maybe his diet (which I'm working on) I am now trying to cut out all red meat to see if that helps him. But someone recently told me about this gluten free diet that may help him. I'm trying to find out more about that. I will try just about anything to help him. Thanks Tina