Please advise me on my dad, WKS?

OK, so my dad dranks again new years 2013 he then was forced to go to rehab in michigan, he did well came back Feb 6 ( my bday 2013 ) his mom died at the funeral he was fine, mentally and physically. He went in april 2013 for a twilight sedation for an upper Gi, seems since that moment he has changed forever…was it actually the sedation that through him over or was it the meds from the psychologist…LYTHIUM?? or is this really it, all the years of abuse have finally kicked in and now this is just his reality, he is in a nursing home, using a walker, feeling dizzy, confused angry and no smile left on his face at all EVER as before…is it too late for thiamine?? will it make a difference now…I have so many unanswered questions…please email me if you know anything to help…I appreciate all advice, experinces etc …would like him to have some sort of life left