Drug use and neurological conditions?

I have a friend that has been diagnosed with Acute Dissiminative encephalomyelitis. We smoke weed daily, and sometimes like to take MDMA. We're not drug heads or burnouts, but we do enjoy the experience i guess you could say. He is curious if he will ever be able to take MDMA again, and is extremely eager to smoke again. I don't see a problem with the cannabis, but I was uncertain about the X. The doctors are saying his condition is only temporary and his brain will completely heal itself. They're saying once it's gone, it's gone. This is giving him the impression that he will be able to do it again and is arguing with me when I tell him he can't. If I were to ask one of the doctors they would completely blow me off for reasons you might imagine. Does anybody know if he will be able to after an MRI reveals he is normal?