Gorilla and the Bird (1970)

Zack, a public defender with the Legal Aid Society of New York, suffers a sudden psychotic break that takes him on a harrowing journey of delusions and antisocial behavior, resulting in his arrest and commitment to Bellevue. As he fights to regain his sanity, Zack (the Gorilla) turns to the only person who didn't give up on him — his mother (the Bird).