I would give homeopathy a try. It significantly improved me. I use a homeopath named Dana Ullman. You can research him online and find all his contact info there. He does over the phone consultations. There are other homeopaths that im sure a quite well versed in concussions and could just as effectively help out your son in law. He was able to significantly improve my symptoms and I am pretty much completely healed after his remedy and time. Dont worry, he will heal I promise it just takes time like everyone says. Make sure he lays off the alcohol and drugs (tobacco) those will slow down healing.