Oral prolonged-release ketamine in treatment-resistant depression - A double-blind randomized placebo-controlled multicentre trial of KET01, a novel ketamine formulation - Clinical and safety results

INTRODUCTION

We investigated the antidepressant effects of a novel oral prolonged-release formulation of racemic ketamine (KET01) in patients suffering from treatment-resistant depression (TRD) as add-on therapy.

MATERIAL AND METHODS

Patients were randomized to an additional 160 mg/day or 240 mg/day KET01 or placebo for 14 days. The primary endpoint was change in Montgomery-Åsberg Depression Rating Scale (MADRS) scores from baseline to day 15. For treatment group comparisons, we used ANOVA with pairwise least squares mean difference tests in a mixed model repeated measures analysis.

RESULTS

Twenty-seven patients completed the double-blind protocol before trial premature termination due to poor recruitment during the COVID-19 pandemic. Mean (SD) MADRS scores on day 15 were 23 (10.32) in placebo, 25 (8.28) with 160 mg/day and 17 (10.32) with 240 mg/day KET01. MADRS change was numerically larger but statistically non-significant in the 240 mg/day KET01 group vs placebo on day 7 (-5.67; p = 00.106) and day 15 was (difference: 4.99; p = 00.15). In exploratory analysis, baseline leukocyte count correlated with response to KET01 (p = 00.01). Distribution of adverse event rates were comparable between the treatment arms. Safety analysis did not identify increased risk of suicidality, dissociation, hear rate, systolic and diastolic blood pressure associated with trial treatment.

DISCUSSION

Our results suggest that adjunctive oral administration of prolonged-release ketamine at a dose of 240 mg/day shows a positive, although statistically non-significant, trend towards antidepressant efficacy, however, the benefit could not be confirmed due to premature trial termination. Given its ease of use and low side effects, further trials are warranted to investigate this route of ketamine administration as a promising potential treatment of TRD.

Experimentally induced and real-world anxiety have no demonstrable effect on goal-directed behaviour

BACKGROUND

Goal-directed control guides optimal decision-making and it is an important cognitive faculty that protects against developing habits. Previous studies have found some evidence of goal-directed deficits when healthy individuals are stressed, and in psychiatric conditions characterised by compulsive behaviours and anxiety. Here, we tested if goal-directed control is affected by state anxiety, which might explain the former results.

METHODS

We carried out a causal test of this hypothesis in two experiments (between-subject N = 88; within-subject N = 50) that used the inhalation of hypercapnic gas (7.5% CO2) to induce an acute state of anxiety in healthy volunteers. In a third experiment (N = 1413), we used a correlational design to test if real-life anxiety-provoking events (panic attacks, stressful events) are associated with impaired goal-directed control.

RESULTS

In the former two causal experiments, we induced a profoundly anxious state, both physiologically and psychologically, but this did not affect goal-directed performance. In the third, correlational, study, we found no evidence for an association between goal-directed control, panic attacks or stressful life eventsover and above variance accounted for by trait differences in compulsivity.

CONCLUSIONS

In sum, three complementary experiments found no evidence that anxiety impairs goal-directed control in human subjects.

Focusing the Neuroscience and Societal Implications of Cognitive Enhancers

Cognitive enhancement can benefit the individual and society, but also has associated risks and ethical concerns. Cognitive-enhancing drugs are used in the treatment of neuropsychiatric disorders. Nonpharmacological strategies are also emerging, which have the potential to improve motivational deficits associated with neuropsychiatric symptoms and should be prioritized for development. The increasing lifestyle use of "smart" and other drugs indicates the desire for healthy people to improve themselves. Safety and ethical implications are discussed.

Neural correlates of 'pessimistic' attitude in depression

BACKGROUND

Preparing for potentially threatening events in the future is essential for survival. Anticipating the future to be unpleasant is also a cognitive key feature of depression. We hypothesized that 'pessimism'-related emotion processing would characterize brain activity in major depression.MethodDuring functional magnetic resonance imaging, depressed patients and a healthy control group were cued to expect and then perceive pictures of known emotional valences--pleasant, unpleasant and neutral--and stimuli of unknown valence that could have been either pleasant or unpleasant. Brain activation associated with the 'unknown' expectation was compared with the 'known' expectation conditions.

RESULTS

While anticipating pictures of unknown valence, activation patterns in depressed patients within the medial and dorsolateral prefrontal areas, inferior frontal gyrus, insula and medial thalamus were similar to activations associated with expecting unpleasant pictures, but not with expecting positive pictures. The activity within a majority of these areas correlated with the depression scores. Differences between healthy and depressed persons were found particularly for medial and dorsolateral prefrontal and insular activations.

CONCLUSIONS

Brain activation in depression during expecting events of unknown emotional valence was comparable with activation while expecting certainly negative, but not positive events. This neurobiological finding is consistent with cognitive models supposing that depressed patients develop a 'pessimistic' attitude towards events with an unknown emotional meaning. Thereby, particularly the role of brain areas associated with the processing of cognitive and executive control and of the internal state is emphasized in contributing to major depression.