The acute phase of this study will monitor the response to a combination of an atypical antipsychotic medication olanzapine with an antidepressant medication sertraline in the acute treatment of the disorder. It is predicted that this combination will improve symptoms of psychotic depression and be associated metabolic side effects. Factors that moderate tolerability will be monitored. Improvement in symptoms could take between 4 and 12 weeks, followed by a period of 8 weeks during which participants will continue to take the same medications to stabilize the remission from symptoms of psychotic depression.

The maintenance phase will be a randomized, double-blind, placebo-controlled study of olanzapine for a period of up to 36 weeks to test whether continuing this combination decreases the risk of relapse and whether discontinuing the combination leads to improvement in metabolic measures. Subjects who complete the acute phase will be asked to consent separately to the randomized maintenance phase.

The original STOP-PD study established that the combination of olanzapine and sertraline was significantly better than olanzapine alone in achieving remission of psychotic depression. This STOP-PD-II Sustaining Remission study aims to assess the long-term tolerability of taking this combination of medications and their efficacy at preventing a relapse of the symptoms. The acute phase of the study will monitor the efficacy and tolerability of the olanzapine and sertraline combination, including investigation of weight and metabolic variables, age effects on treatment response and tolerability, and the association of genetic polymorphisms to response or relapse. When subjects are stabilized on these medications for a period of 8 weeks they will be invited to participate in the randomized phase of the research: the olanzapine will be placebo-controlled, meaning half of the subjects will continue to take the olanzapine/sertraline combination and half will take a sertraline/placebo combination, for a period of 36 weeks. Symptoms and side effects will be monitored regularly throughout this phase. Randomization will be stratified on a 1:1 basis by age 60 and above.

Inclusion Criteria:

1. Aged 18-85 years, inclusive
2. Diagnosis: Diagnostic Statistical Manual-IV Trade Revision (DSM IV-TR) non-bipolar major depression with psychotic features established by both clinical interview with research psychiatrist and administration of SCID-IV.
3. Score >2 on Schedule for Affective Disorders (SADS) delusion severity item
4. Score >1 on any of the three conviction items of the Delusion Assessment Scale (DAS) (does not alter belief in response to reality testing)
5. 17-item HAM-D score of >20

Exclusion Criteria:

1. Current or lifetime DSM-IV-TR history of schizophrenia or other psychotic disorders or meeting current criteria for brief psychotic disorder, body dysmorphic disorder or obsessive-compulsive disorder
2. Current or lifetime DSM-IV-TR bipolar affective disorder
3. History of DSM-IV-TR defined alcohol or substance abuse or dependence within the past three months
4. Dementia or clinically significant cognitive impairment prior to index episode of depression, and/or a mean score >3 on 26-item caregiver assessment
5. Type 1 diabetes mellitus (defined as insulin-dependent diabetes mellitus with onset before age 35, and/or diabetes mellitus complicated by prior documented episode of ketoacidosis
6. Acute or unstable medical illness within the past 3 months; current abnormal serum free T4; current abnormally low vitamin B4 or folic acid level; medical conditions and/or medications for which psychotic or depressive symptoms can be a direct manifestation; neurological disease associated with extrapyramidal signs and symptoms; epilepsy, if the person has had one or more grand mal seizures within the past 12 months.
7. The need for treatment with any psychotropic medication other than sertraline, olanzapine or lorazepam; or with an anticonvulsant medication with mood-stabilizing properties.
8. Current pregnancy or plan to become pregnant during the course of the study; breast feeding in women with infants.
9. A documented history of being unable to tolerate olanzapine or sertraline including significant bradycardia (heart rate of <50 bpm), and serum sodium level of 129mmol/L or below.
10. History of non-response of the index episode of psychotic depression to at least a 6-week trial of at least 150mg/day sertraline combined with 15mg/day olanzapine
11. Patients showing ongoing improvement in current episode of psychotic depression with treatment other than sertraline or olanzapine
12. Patients who are in immediate need of electroconvulsive therapy (ECT) (imminent risk of suicide, refusing to eat, catatonic)

36 Weeks of RCT Phase

Are based on items of the Udvalg for Kliniske Undersogelser Side effect scale (UKU), based on the following system: 1) Items with an increase of ≥2 points from baseline and items rated as a 3 on the UKU that were rated <3 at baseline. Exceptions include the following items: 35=Weight Gain, 36= Weight Loss. 2) Weight gain and weight loss AEs were determined by the following definitions: a. weight gain of >7% from pre-morbid weight, b. weight loss of >7% from pre-morbid weight in the RCT phase.