Dude knows his stuff

Except for Joker. While he's right in that Arthur Fleck suffers from pseudobulbar affect, Fleck shows traits more consistent with borderline personality disorder, schizophrenia*, and bipolar disorder than he does psychopathy (which, I admit, is amusing considering most versions of Mr J are psychopaths).

Also, it kinda bugs me slightly that the psychiatrist didn't break down Matchstick Men considering Matchstick Men's a pretty accurate portrayal of OCD, as this clip shows:

*Alternatively, Fleck might have schizoaffective disorder - depressive type.