One flew over the Cuckoos Nest?

i can not seem to figure out what disorder some of the characters have. I know that billy has major depressive disorder, but what disorder does taber aka the chief have? i dont know wat disorder makes you deaf and mute? also Cheswick, i know he acts like a child but wat is his disorder called? and Martini, i think he has scziohphrenia but i am not sure.. What disorder does he have? and Dale, he is paranoid but i am not sure if he has sczophrenia.. Help me out guys! Thank you :)