There didn't seem to be any mention that the man was mentally ill.
The problem is that "mentally ill" doesn't mean what it used to imply.
By today's standards, there are MANY people (politicans and doctors included) who would consider Christians, gun owners, defenders of the Constitution, and those of use post here as "mentally ill".
The use of mind-alterting drugs was, I believe, one of the many tools the communists in Russia used to place people in submission to the state.