It was me who recommended the Vit B.
B12 is one of the Vits recommended. But a B complex would be the best. In the past I have given people injections of Parentrovite, which is a b complex, stinks,mind. But that is only with serious alcohol abuse.
If your father has a history of alcohol abuse is this recent or past history. When did he last ahve a drink, this could be important considering his mood swings.
It has also been noted now that vits are good for those with failing memeories. I remember something about combining vit e with something..sorry about the vagueness if I find it I will post here.