Treatment for Memory Loss Due to Concussion

My brother in law (64 years old) was in a car accident 4 weeks ago. He didn't have on his seat belt and the air bag hit him in his face. He was diagnosed with a concussion. He spent two and a half weeks in hospital. The first week he basically slept. The second week he was more alert, opening his eyes and acknowledging his visitors. His short term memory and almost the last year of his life he doesn't remember. He refuses to do everyday things like bathing and gets very irritated when you try to push him to do things. He keeps insisting he wants to go home but doesn't know where home is. He has to be watched continuously as any chance he gets he tries to go outside, convinced he has an appointment or needs to go home. Anything you ask, his immediate response is "NO". Lets go for a drive, NO, etc.

We feel helpless. Is there anything we can do to stimulate his memory. We don't think just sitting at home all day is going to help. I think of it as a cut we are leaving to heal on its own instead of dressing it everyday to speed up the process. There must be something, we couldn't be trying to reinvent the wheel.