The two main characters suffer from the worst disorders. First there is Catherine (Merle Oberon). She is a very clingy person, who has her moments of happiness followed directly by moments of anger and sadness. With the introduction of Prozac into her life, her mood swings would stabilize; and she would not have to rely on others to make her happy.
Heathcliff (Laurence Olivier) also suffers from drastic mood swings but also is very depressed. He is always trying to prevail over everyone else. Prozac in his case will help him mellow out, and he would be able to function with out the fear of failing or the need to overcome.
Also the supporting characters suffer from disorders. Joseph (Leo G. Carroll) is paranoid. He is afraid of Heathcliff, Hindley and God. I think he suffers from an anxiety disorder. In his case Prozac would help calm his nerves and allow him to live without fear. Hindley (Hugh Williams) is an alcoholic, and Prozac has been proven to help kick the habit. Edgar Linton (David Niven) is obsessive and compulsive. He is very clean in his manners and needs to be in control. Prozac will allow him to deal with others without having to feel like he needs to protect or control them. Also I believe his sister, Isabella (Geraldine Fitzgerald), is depressed because first she is alone and then in a loveless relationship. With her Prozac could help bring more confidence and help her overcome the obstacles that are holding her back.
William Wyler's Wuthering Heights shows all of these disorders at their pinnacle. He uses facial expressions and movement to show that they are mentally unstable. Catherine has her moments of close-ups with crazed eyes, and Hindley is obviously drunk and mean throughout the picture.
One can see Prozac would help the characters deal with the life that they face at Wuthering Heights. The drug would make everyone happier and would allow the story to play out differently, maybe with a happier ending.