The laughing condition was clear and possible Schizophrenia and PTSD were directly tied to the circumstances he found himself in. I think the first murders and subsequent reaction of Gotham probably triggered some NPD, but i don't think those had anything to do with his mental illness. It was obviously self-defence.

after that, yeah, i think its up to interpretation

>You could say this is picky, but a movie about how badly
>society treats people with mental illness should at least tell
>us what mental illness the main character has, instead of
>basically shrugging and saying he has whatever mental illness
>makes him fucked up and cwaaaaazy.

idk if it matters which illnesses he has since A. its Joker, and B. it seemed like the movie was just pointing at the lack of help for anybody with any illness in Gotham. I mean, you were already sympathising with Arthur anyway so i think getting granular with which illness he has is kinda doing to much for a 2.5hr movie about the Joker.

They're definitely walking a line. i agree with that.