I knew Yeltsin was an alcoholic. What I have read is that this was VERY well known to those at the top in the US. They promoted Yeltsin specifically because he would be easier to manipulate because of his alcohol problem. The US openly bragged about manipulating the election in Russia in 1995 (IIRC the year). This is part of the reason why Russia devolved so harshly in the 90s, leading to an authoritarian like Vladimir Putin taking over.