Adjunctive Vortioxetine in Schizophrenia

Inclusion Criteria: 1. Outpatient 2. SCID diagnosis of schizophrenia 3. Age 18-65 years old 4. Treated with an adequate dose of one or a maximum of two antipsychotic medications for at least 3 months, with a stable dose for at least the last 4 weeks, and willing to continue for up to 16 weeks. 5. No antidepressant treatment for at least 8 weeks prior to randomization. 6. Treatment with other concomitant, non-antipsychotic, psychiatric medications is allowed, but must be unchanged for at least 8 weeks, with a stable dose for at least the last 4 weeks, and willing to continue for 16 weeks. Benzodiazepines must not be given within 8 hours of the cognitive assessment. Treatment with non-psychiatric medications is unrestricted. 7. PANSS Negative subscore \>14 with at least two of the items at a level \>/=4 (moderate) 8. PANSS Positive subscore \</=14 with not more than one of the items at a level \>/=4 (moderate) for patients who have been stable outpatients for \<1 year. A PANSS Positive subscore of \</=18 is acceptable for patients who have been stable outpatients for \>/=1year and whose psychotic symptoms do not affect behavior in a clinically relevant way as per investigator assessment. - . In order to avoid simple double counting, any rating on P1 ("delusions") will not be considered as an additional symptom for determination of eligibility based on PANSS positive subscore when a specific delusion is present that is rated either on P5 ("grandiosity") or P6 ("suspiciousness/paranoia"), whereas delusions not captured by P5 ("grandiosity") or P6 ("suspiciousness/paranoia"), will be rated under P1 ("delusions") and counted toward the sum score used to determine study eligibility). 9. HAMD-17 total score \</=12 10. Simpson Angus Score of any item \<3 11. English-speaking 12. Competent and willing to sign informed consent Exclusion Criteria: 1. Structural brain disease 2. Mental retardation by history and estimated IQ \<70 (WRAT-III Word Reading) 3. Autism-spectrum disorder diagnosis by history 4. Any serious chronic medical illnesses that in the view of the investigator will interfere with the patient's ability to comply with the study procedures or that will interfere with cognition. 5. Active substance abuse or dependence in the past 8 weeks 6. Intolerance to or inefficacy of vortioxetine in the past 7. Acute anger to self or others as per investigator assessment 8. Pregnant or breastfeeding females 9. Unwilling or unable to be sexually abstinent or not using an effective form of birth control if they are sexually active 10. Current treatment with a Monoamine Oxidase Inhibitor (MAOI)