This is pretty normal Wamama - it takes a long time in early recovery for the brain to start functioning "normally" again.
It's INCREDIBLY frustrating on this side of the street, but it's legit bio-neuro-issues in most cases.
He's been saturating his body in alcohol for years, right? That kind of damage doesn't reverse in a few weeks - for some there are permanent changes as a result of aging + the abuses of their addictions.
I'd keep my expectations very, very low.