Hello.
Mood Disorder with Psychosis does need a combination of medication quite often. Olanzapine may not be sufficient. Olanzapine is known to have effects on mood, however, it is not the first line treatment for a mood disorder. You might consider talking with the doctor about adding a mood stabilizer (if the mood disorder is bipolar). Olanzapine may be withdrawn gradually once the psychosis is treated. The mood stabilizer will remain as the mainstay of his treatment.
This is a suggestion. You can talk with his doctor regarding this.
Take care.
Abhijeet Deshmukh, MD
(This post is for the purpose of providing medical information and is not a substitute for a face-to-face consultation with a doctor. This post is not intended to give or rule out a diagnosis, create a doctor-patient relationship or replace an existing one. I am not able to diagnose medical conditions online. Please consult with your doctor or a qualified healthcare provider for diagnosis and treatment options)