The Effects of Vortioxetine on Cognitive Function in Patients with Major Depressive Disorder: A Meta-Analysis of Three Randomized Controlled Trials

BACKGROUND Management of cognitive deficits in Major Depressive Disorder (MDD) remains an important unmet need. This meta-analysis evaluated the effects of vortioxetine on cognition in patients with MDD. METHODS Random effects meta-analysis was applied to three randomized, double-blind, placebo-controlled 8-week trials of vortioxetine (5-20mg/day) in MDD, and separately to two duloxetine-referenced trials. The primary outcome measure was change in Digit Symbol Substitution Test (DSST) score. Standardized effect sizes (SES) versus placebo (Cohen's d) were used as input. Path analysis was employed to determine the extent to which changes in DSST were mediated independently of a change in Montgomery-Åsberg Depression Rating Scale (MADRS) score. Meta-analysis was applied to MADRS-adjusted and -unadjusted SES values. Changes on additional cognitive tests were evaluated (source studies only). RESULTS Before adjustment for MADRS, vortioxetine separated from placebo on DSST score (SES 0.25-0.48; nominal p < 0.05) in all individual trials, and statistically improved DSST performance versus placebo in meta-analyses of the three trials (SES = 0.35; p < 0.0001) and two duloxetine-referenced trials (SES = 0.26; p = 0.001). After adjustment for MADRS, vortioxetine maintained DSST improvement in one individual trial (p = 0.001) and separation from placebo was maintained in meta-analyses of all three trials (SES = 0.24; p < 0.0001) and both duloxetine-referenced trials (SES 0.19; p = 0.01). Change in DSST with duloxetine failed to separate from placebo in individual trials and both meta-analyses. Change in DSST statistically favored vortioxetine versus duloxetine after MADRS adjustment (SES = 0.16; p = 0.04). CONCLUSIONS Vortioxetine, but not duloxetine, significantly improved cognition, independent of depressive symptoms. Vortioxetine represents an important treatment for MDD-related cognitive dysfunction.