Inclusion Criteria:  Outpatient Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders (DSM - SCID) diagnosis of Schizophrenia spectrum disorders. Age >18-50 years old Stable antipsychotic medication doses during at least 4 weeks ( all second generation antipsychotics excluding clozapine). No antidepressant treatment for at least 8 weeks prior to randomization. PANSS Negative subscore >14 with at least two of the items at a level >/=4 (moderate) PANSS Positive subscore </=14 with not more than one of the items at a level >/=4 (moderate) Hamilton Depression Rating Scale (HAMD-17) total score </=12 Simpson Angus Score of any item <2 Behaviorally Anchored Rating Scale (BARS) of any item </= 1 Competent and willing to sign informed consent The patient, if a woman, must: agree not to try to become pregnant during the study and use adequate, highly effective contraception  Exclusion Criteria:  Patients taking any antidepressant and its use cannot be discontinued at least 8 weeks prior to randomization. Structural brain disease (based on previous medical records) Cognitive disability by history and estimated intelligence quotient (IQ) <70 (ID DSM-5 diagnosis). Any serious chronic medical illnesses that may interfere with the patient's ability to comply with the study procedures or that will interfere with cognition. Organic mental disorders, or mental disorders due to a general medical condition. Any neurological or neurodegenerative disorders. Any current diagnosis of substance abuse or dependence. Serious risk of suicide. Patients with thyroid conditions. Intolerance to or inefficacy of vortioxetine in the past. Patients who had failed treatment with vortioxetine were also excluded. Pregnant or breastfeeding female.