I've seen offhand comments made about this but I don't think there's ever been an in-depth discussion. A bunch of people have used the SNL skit as proof given how awkward Ren acts there while trying to interact with people. But obviously that's not canon, though I did notice some character choices that support the theory.

1) With the mask off, Kylo has trouble maintaining eye contact. He frowns a lot and looks away.
2) He doesn't seem to be able to understand people in general. He does things like kidnap Rey and then is genuinely surprised that she wants to kill him.
3) He acts very immature for his age and clearly has poor coping mechanisms.
4) He is singleminded and obsessive over one thing (Vader).