I shudder to think...what?
(I've heard the idea that Harry is actually in a sanitorium suffering from PTSD, and how the story and his place in it matches the kind of delusions you'd expect. It was scarily convincing...)
Sort of similar, actually, except it was early-onset schizophrenia, with him initially struggling against it and eventually giving in and embracing his delusions and hallucinations. Stefan seems to be convinced that magic is always an allegory for insanity. Given the kind of life he had before he turned eleven, Harry should
have PTSD at the least, or probably more likely, DID.