In Bret Easton Ellis' American Psycho, the protagonist, Patrick Bateman, is apparently simply a psychopath. However, Bateman can be diagnosed with other mental illnesses such as Asperger's syndrome, obsessive-compulsive disorder, schizophrenia, narcissism, and antisocial personality disorder.

Was it all in Patrick Bateman's head?

It makes it look like it was all in his head, and as far as I'm concerned, it's not.” Thus, many of the above scenes aren't supposed to be evidence that the murders didn't happen but are supposed to reflect Bateman's deteriorating mental state and the loss of his grip on any semblance of reality.

What personality type is Patrick Bateman?

Patrick Bateman is an unhealthy ENTJ Myers & Briggs personality type. He is determined to get what he wants and will step over anyone who gets in his way.