Just to be sure, because I'm a nit-picky little pedant: You do mean psychosis and not psychopathy, yes?
Psychosis, the state of being psychotic, is to suffer delusions or hallucinations , to have disorganized speech, or even suffer catatonia. To put simply it is to suffer insanity.
Psychopathy on the other hand is a personality disorder. Psychopaths exhibit numerous traits. They can be charming, self-aggrandizing, manipulative and lack empathy or remorse, among other things. To put it plainly they essentially lack a conscience but are very intelligent.
Most people oft use them interchangeably but they're very different... Anyway to cut to the chase, does The Corruption induce both of these things to varying severity? Again, sorry for being a nitpicking twat. I just like details too much...
If i could describe it simply. It starts off as Psychopathy, then it gradually develops into serious Psychosis. When you see the fully corrupted ponies then you'll see, but i figure you understand what i'm trying to say by this alone.