Iron causes insanity by inverting the dopamine receptors - they "punish" the neurons when dopamine is absent, instead of when it's present, so people seek conflict, abhor cooperation, and learn to be as vicious as possible and they think it makes them good. When you "fortify" food with iron, you aten't making people smart and democratic, you're just making them insane and vicious. (but you like it, so they feel pleasant and funny to you when you are also poisoned)
One thing it inverts is that you seek stress instead of avoiding it. That makes people trying to be social by stressing the other person, and develop "social skills" to be as annoying and unpredictable as possible, so that people around them are stressed and seek their presence, and punish those they dislike by not allowing them to experience any stress. (i.e. silent treatment) A schizophrenic can be tortured in a silent white room, where they have no oppirtunity to experience stress, do they suffer as a normal person would if their house was burning, their children were being killed and their wife raped.
It also inverts the cognitive filters, so the most unimportant thing seems crucial, and critical parts seems unimportant. (known and widely noticed as variously the bike shed effect, or the elephant in the room)
It has an effect on speech and communication as well - you can notice the person talks at length about things vaguely relevant, briefly mentions what is important, or even conpletely lefts out the most crucial pieces of information. When the schozophrenic listens, he notices the details the most, and males up what was left out, what should be said and wasn't. So that schizophrenics (sort of, it's still highly unreliable) understand each other, as the effects mostly cancel out, but communicating with them is basically impossible, even when there is will on both sides.