I believe everyone in FF8 has some type of disorder.

Zell has ADHD
Squall is neurotic with anti-social personality disorder
Rinoa has dependent personality disorder
Seifer has narcissistic personality disorder
Quistis has OCD and coupled with a type a personality
Irvine probably has some form of narcissistic personality disorder and Don Juan syndrome

and Selphie maybe also another form OCD in which one becomes emotionally attached to inanimate object