Up until capone was released from alcatraz he was in sound mind,his syphilis was in check, he was taking his medication and he also was working out a few times a week, but when they released him from alcatraz and sent him to terminal island for a questionable experimental treatment for his syphilis, that's why he started to loose it, they pumped him full of mercury and that's what did the damage to his brain


"McGurn likes you, so I make you. So you are now one of us, if you fuck up, we take it out on McGurn. He is your sponsor. Fuck up, it's his ass. You work in his crew, he is your capo."