Given the wide implications of cognitive impairment for prognosis and outcome in schizophrenia, the research on pharmacological approaches aimed at addressing dysfunctional cognition has been extensive; nevertheless, there are no currently available licensed drugs, and the evidence in this field is still unimpressive. Vortioxetine is a multimodal antidepressant, which has been proposed as a suitable treatment option for cognitive symptoms in depression.
Twenty schizophrenia outpatients (mean age ± SD, 40.7 ±10.6 years) on stable clozapine treatment, assessed by neuropsychological (Wisconsin Card Sorting Test, Verbal Fluency, and Stroop task) and psychodiagnostic instruments (Positive and Negative Syndrome Scale [PANSS] and Calgary Depression Scale for Schizophrenia), received vortioxetine at the single daily dose of 10 mg/d until week 12; the dose was increased at 20 mg/d afterward, and this dosage was maintained unchanged until week 24. A physical examination, electrocardiogram with QTc measurement, and laboratory tests were also performed.
Vortioxetine supplementation significantly improved Stroop test (P = 0.013) at week 12 and Stroop test (P = 0.031) and Semantic Fluency (P = 0.002) at end point. Moreover, a significantly reduction of PANSS domains “positive” (P = 0.019) at week 12 and of PANSS domains positive (P = 0.019) and total score (P = 0.041) and of depressive symptoms (Calgary Depression Scale for Schizophrenia, P = 0.032) at end point. There was no significant change in clinical, metabolic, and safety parameters, and no subject spontaneously reported adverse effects.
Despite the limitations (open design, lack of a control group, small sample size, and short intervention period), our findings suggest for the first time that vortioxetine augmentation of clozapine may be a promising therapeutic strategy for addressing cognitive deficits in patients with schizophrenia.