The effects of vortioxetine on cognitive dysfunction in patients with inadequate response to current antidepressants in major depressive disorder: A short-term, randomized, double-blind, exploratory study versus escitalopram.

BACKGROUND: Major Depressive Disorder (MDD) is a heterogeneous disease characterized by emotional, physical and cognitive symptoms. This study explored the effects of vortioxetine versus escitalopram on outcomes of cognition, functioning and mood symptoms in depressed patients with inadequate response to current antidepressant treatment. METHODS: In this parallel-group, active-comparator study, adult patients (18-65 years, N = 101) with MDD, with inadequate response to current antidepressant monotherapy, were randomized 1:1 to 8 weeks' double-blind treatment with flexible doses (10-20mg/day) of either vortioxetine or escitalopram. Primary and key secondary efficacy measures were the Digit Symbol Substitution Test (DSST), analyzed using a mixed model for repeated measurements, and the University of San Diego Performance-based Skills Assessment - Brief (UPSA-B), analyzed using analysis of covariance (last observation carried forward method). RESULTS: At week 8, DSST and UPSA-B performance had improved in both treatment groups, with no statistically significant treatment differences. Numerical improvements across measures of cognition, functioning and mood symptoms generally favored vortioxetine. Most adverse events were mild or moderate, with nausea being the most common adverse event. LIMITATIONS: This was an exploratory study with small sample sizes implying limited statistical power. CONCLUSION: Although this explorative study did not meet primary endpoints, the results confirm vortioxetine in doses of 10-20mg/day as an efficacious and well-tolerated antidepressant switch treatment. The overall direction of numerical effect sizes across cognition endpoints support previous findings that vortioxetine specifically benefits cognitive function in MDD.

The effects of vortioxetine on cognitive performance in working patients with major depressive disorder: A short-term, randomized, double-blind, exploratory study.

BACKGROUND: Major Depressive Disorder (MDD) is a complex disease characterized by emotional, physical and cognitive symptoms. We explored the efficacy of vortioxetine versus placebo on outcomes of cognition, functioning and mood symptoms in working patients with depression, using paroxetine as an active reference. METHODS: Gainfully employed patients (18-65 years, N = 152) with MDD were randomized 1:1:1 to 8 weeks' double-blind, parallel treatment either with vortioxetine (10mg/day) or paroxetine (20mg/day), or with placebo. The primary efficacy measure was the Digit Symbol Substitution Test (DSST), analyzed using a mixed model for repeated measurements, and the key secondary efficacy measure was the University of San Diego Performance-based Skills Assessment - Brief (UPSA-B), analyzed using analysis of covariance (last observation carried forward). RESULTS: At week 8, DSST and UPSA-B performance had improved relative to baseline in all treatment groups, with no statistically significant differences between treatment groups. While improvements in mood were comparable for vortioxetine and paroxetine, numerical improvements in cognitive performance (DSST) were larger with vortioxetine. Vortioxetine significantly improved overall cognitive performance and clinician-rated functioning relative to placebo. The majority of adverse events were mild or moderate, with nausea being the most common adverse event for vortioxetine. LIMITATIONS: Small sample sizes implied limited statistical power. CONCLUSION: This explorative study showed no significant differences versus placebo in DSST or UPSA-B performance at week 8. However, secondary results support vortioxetine as an effective and well-tolerated antidepressant, supporting an added benefit for cognition and functioning, which could have particular therapeutic relevance for the working patient population.

Which Cognitive Domains are Improved by Treatment with Vortioxetine?

BACKGROUND: These post hoc analyses evaluated vortioxetine efficacy on cognitive dysfunction in depression. Data were from a double-blind, randomized, fixed-dose, placebo-controlled, 8-week depression study in adults aged 18-65 years (n = 602) with DSM-IV-defined major depressive disorder (MDD). Subjects were randomized (1:1:1) to vortioxetine 10mg/day or 20mg/day or placebo. METHODS: Cognitive function was assessed at baseline, Week 1 (10mg/day only) and Week 8 using Digit Symbol Substitution Test (DSST) number of correct symbols, Rey Auditory Verbal Learning Test, Trail Making Test, Stroop test, Simple Reaction Time, and Choice Reaction Time tests. The cognition variables were standardized and used for constructing composite Z-scores for the cognitive domains of executive function, attention/speed of processing, and memory. RESULTS: At Week 1, vortioxetine 10mg/day separated from placebo for attention/speed of processing (standardized composite Z-score = 0.21; p = 0.0238) and DSST number of correct symbols (standardized effect size = 0.18; p = 0.0458) and for executive function (standardized composite Z-score = 0.20; p = 0.0274). At Week 8, vortioxetine 10mg/day and 20mg/day separated from placebo for executive function and attention/speed of processing, with standardized composite Z-scores ranging from 0.35 to 0.49 (all p < 0.01). Standardized composite Z-scores for memory were 0.31 ( p = 0.0036, 10mg/day) and 0.22 ( p = 0.0349, 20mg/day). Standardized effect sizes for DSST were 0.51 ( p < 0.0001, 10mg/day) and 0.52 ( p < 0.0001, 20mg/day). Results are limited by the post hoc nature of the analyses and the absence of an active reference in the original study. CONCLUSIONS: Vortioxetine (10 and 20mg/day) had a multi-domain beneficial effect on cognitive performance, as evidenced by improvements in measures of executive function, attention/speed of processing, and memory. The effect on the DSST may be due to improvements in several cognitive skills.

Effects of serotonin in the hippocampus: how SSRIs and multimodal antidepressants might regulate pyramidal cell function.

The hippocampus plays an important role in emotional and cognitive processing, and both of these domains are affected in patients with major depressive disorder (MDD). Extensive preclinical research and the notion that modulation of serotonin (5-HT) neurotransmission plays a key role in the therapeutic efficacy of selective serotonin reuptake inhibitors (SSRIs) support the view that 5-HT is important for hippocampal function in normal and disease-like conditions. The hippocampus is densely innervated by serotonergic fibers, and the majority of 5-HT receptor subtypes are expressed there. Furthermore, hippocampal cells often co-express multiple 5-HT receptor subtypes that can have either complementary or opposing effects on cell function, adding to the complexity of 5-HT neurotransmission. Here we review the current knowledge of how 5-HT, through its various receptor subtypes, modulates hippocampal output and the activity of hippocampal pyramidal cells in rodents. In addition, we discuss the relevance of 5-HT modulation for cognitive processing in rodents and possible clinical implications of these results in patients with MDD. Finally, we review the data on how SSRIs and vortioxetine, an antidepressant with multimodal activity, affect hippocampal function, including cognitive processing, from both a preclinical and clinical perspective.

A randomized, double-blind, placebo-controlled study of vortioxetine on cognitive function in depressed adults.

The efficacy of vortioxetine 10 and 20 mg/d vs. placebo on cognitive function and depression in adults with recurrent moderate-to-severe major depressive disorder (MDD) was evaluated. Patients (18-65 yr, N = 602) were randomized (1:1:1) to vortioxetine 10 or 20 mg/d or placebo for 8 wk in a double-blind multi-national study. Cognitive function was assessed with objective neuropsychological tests of executive function, processing speed, attention and learning and memory, and a subjective cognitive measure. The primary outcome measure was change from baseline to week 8 in a composite z-score comprising the Digit Symbol Substitution Test (DSST) and Rey Auditory Verbal Learning Test (RAVLT) scores. Depressive symptoms were assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS). In the pre-defined primary efficacy analysis, both doses of vortioxetine were significantly better than placebo, with mean treatment differences vs. placebo of 0.36 (vortioxetine 10 mg, p < 0.0001) and 0.33 (vortioxetine 20 mg, p < 0.0001) on the composite cognition score. Significant improvement vs. placebo was observed for vortioxetine on most of the secondary objectives and subjective patient-reported cognitive measures. The differences to placebo in the MADRS total score at week 8 were -4.7 (10 mg: p < 0.0001) and -6.7 (20 mg: p < 0.0001). Path and subgroup analyses indicate that the beneficial effect of vortioxetine on cognition is largely a direct treatment effect. No safety concern emerged with vortioxetine. Vortioxetine significantly improved objective and subjective measures of cognitive function in adults with recurrent MDD and these effects were largely independent of its effect on improving depressive symptoms.

A schizophrenia rat model induced by early postnatal phencyclidine treatment and characterized by Magnetic Resonance Imaging.

Better animal models are needed to aid the development of new medications to alleviate the cognitive deficits associated with schizophrenia. Growing evidence suggests neurodevelopmental insults and disturbances in NMDA receptor (NMDAR) signaling to be involved in the schizophrenia etiology. Acute administration of phencyclidine (PCP) induces schizophrenia-like symptoms in healthy volunteers and exacerbates symptoms in patients with schizophrenia. In this study, pharmacological Magnetic Resonance Imaging (phMRI) was used to evaluate if rats treated with 20mg/kg PCP on postnatal days 7, 9, and 11 (neoPCP), compared to saline (neoVeh), were hypersensitive to acute PCP administration in adulthood (acutePCP). Intravenous administration of 0.5mg/kg acutePCP produced robust and sustained relative cerebral blood volume (rCBV) increase in discrete frontal, neocortical, hippocampal, thalamic, and limbic brain structures in both neoPCP:acutePCP and neoVeh:acutePCP rats compared to acute saline treatment (Vehicle control group). AcutePCP injection significantly increased the rCBV response in the medial prefrontal cortex and nucleus accumbens compared to the Vehicle control group, without distinguishing neoPCP and neoVeh animals. However, at late time points (25-33min post acutePCP injection), neoPCP animals showed significantly higher rCBV values compared to the Vehicle control group, suggesting an altered sensitivity toward NMDAR blockade in adult rats subjected to this neurodevelopmental procedure. In combination with the observed cognitive deficits revealed in this animal model, the present findings indicate that altered NMDAR signaling might underlie the symptomatic changes seen in schizophrenia, adding to the construct and face validity of this model.

Antipsychotic-like effect of retigabine [N-(2-Amino-4-(fluorobenzylamino)-phenyl)carbamic acid ester], a KCNQ potassium channel opener, via modulation of mesolimbic dopaminergic neurotransmission.

Dopaminergic (DAergic) neurons in the ventral tegmental area express both KCNQ2 and KCNQ4 channels, which opening is expected to decrease neuronal excitability via neuronal hyper-polarization. Because psychotic symptoms are believed to be associated with an increased excitability of dopamine (DA) cells in the mesencephalon, KCNQ channels might represent a new potential target for the treatment of psychosis. The aim of our study was to investigate the antipsychotic-like potential of KCNQ channel opening via modulation of neuronal activity within the mesolimbic DAergic system. We report that retigabine [N-(2-amino-4-(fluorobenzylamino)-phenyl)carbamic acid ester], a KCNQ opener, dose-dependently reduced basal DA firing rate and more potently suppressed burst firing activity in the ventral tegmental area, whereas XE-991 [10,10-bis(pyridinylmethyl)-9(10H)-anthracenone], a selective KCNQ blocker, induced opposite effects. In addition, retigabine prevented d-amphetamine-induced DA efflux in the nucleus accumbens and d-amphetamine-induced locomotor hyperactivity. In contrast, XE-991 potentiated both the locomotor hyperactivity and DA efflux evoked by d-amphetamine. These data strongly suggest that the activation of KCNQ channels attenuates DAergic neurotransmission in the mesolimbic system, particularly in conditions of excessive DAergic activity. In a model predictive of antipsychotic activity, the conditioned avoidance response paradigm, retigabine was found to inhibit avoidance responses, an effect blocked by coadministration of XE-991. Furthermore, retigabine was found to significantly inhibit the hyperlocomotor response to a phencyclidine (PCP) challenge in PCP-sensitized animals, considered as a disease model for schizophrenia. Taken together, our studies provide evidence that KCNQ channel openers represent a potential new class of antipsychotics.

Classical as well as novel antipsychotic drugs increase self-stimulation threshold in the rat--similar mechanism of action?

Antipsychotic drugs given acutely increase the threshold for intracranial self-stimulation elicited from the ventral tegmental area. As all the antipsychotic drugs share the dopamine D2-receptor antagonism it is reasonable to believe that this is the cause for suppression of intracranial self-stimulation behaviour. The objective of this investigation was to examine the effect of classical (haloperidol) as well as novel antipsychotic drugs (clozapine, olanzapine and sertindole) on intracranial self-stimulation behaviour. Furthermore, the effects of different specific receptor antagonists on intracranial self-stimulation behaviour were examined. Our results showed that both the classical (haloperidol) and the three novel antipsychotic drugs increase the threshold for intracranial self-stimulation. The results obtained with the receptor specific antagonists showed that dopamine D2, alpha1-adrenoceptor and serotonin 5-HT2A receptor antagonisms inhibit intracranial self-stimulation behaviour and that muscarinic receptor antagonism is without effect. Even though all the tested antipsychotic drugs inhibited intracranial self-stimulation behaviour, there seems to be a difference in their ratio between doses that inhibits intracranial self-stimulation behaviour and those that produce antipsychotic effect in a preclinical model (amphetamine hyperactivity). Sertindole was the only antipsychotic drug able to produce antipsychotic effect without significant inhibition of intracranial self-stimulation behaviour at a narrow dose interval. The remaining antipsychotic drugs all inhibited intracranial self-stimulation behaviour at equal or lower doses than those producing antipsychotic effect.