BoxinRotz has seen hell and back with her (R?)AH. If anyone knows about alcohol and neurological problems, she's it. Read and absorb what she's saying.
There's an analogy to help break this advanced progression of alcoholism into layman's terms. We are all born cucumbers. All different, but all with an equal potential as cucumbers. As we all know, cucumbers can be many things. One of those things is a pickle. Alcoholics are pickles. The alcohol soaks the brain and changes it, much the way a brine changes a cucumber into a pickle. If you know one thing about pickles, it's that you can never turn them back into cucumbers. An alcoholic in the advanced stages of addiction is a big kosher dill. Even with recovery, they're never going to be a cucumber again. The brain is so damaged that it won't fully recover. There's a chance he could sober up and he still wouldn't be someone you'd want to have dinner with.
Unfortunately, the only way to know just how much of the original cucumber remains is for him to choose to not add a single drop of alcohol to that pickled brain of his. And there's not a darn thing you can do to force him to do it.