welcome to Healthcare Magic.
I is sad to hear about your brother health. Neuronal injuries often are permanent, so complete recovery is rare in such cases. Over a period of time some improvement in memory and behavior is possible.
After brain injuries some personality changes are possible which can lead to aggressive behavior. In such cases low dose anti psychotic medicines are helpful. For that you can consult some nearby psychiatrist
Wish you all the best.
Dr Ashish Kumar Mittal