Reduction in Cognitive Symptoms Following Intranasal Esketamine Administration in Patients With Chronic Treatment-resistant Depression: A 12-Week Case Series

Background: Cognitive symptoms are a core feature of depressive disorders, interfere with full functional recovery and are prominent in patients with treatment-resistant depression (TRD), particularly in severe chronic cases. Intranasal (IN) esketamine was recently approved for the treatment of TRD; however, its effects on cognitive symptoms are unclear. In this article, we describe cognitive changes in 8 patients with chronic TRD who were treated with IN administration of esketamine. Methods: Eight outpatients with chronic TRD received IN esketamine over 3 months and were assessed at baseline and after 4, 8, and 12 weeks of treatment using the Montgomery-Åsberg Depression Rating Scale (MADRS), the Digit Symbol Substitution Test (DSST), the Trail Making Test-B (TMT-B), the Patient Deficits Questionnaire for Depression 5-item (PDQ-D5), the Hamilton Anxiety Rating Scale (HARS), and the Clinical Global Impressions Scale (CGI). Findings: We observed reductions in cognitive symptoms according to DSST, TMT-B, and PDQ-D5 scores within the first 2 months of treatment with IN esketamine. These improvements were observed before patients achieved clinical response (≥50% decrease in baseline MADRS scores), and they also occurred earlier than reductions in HARS scores. Conclusions: A clinical response to IN esketamine was detected in severely ill patients with chronic TRD after 3 months of treatment. Interestingly, improvements on measures of cognitive symptoms were observed before patients achieved antidepressant response. These preliminary observations suggest an additional value to the antidepressant properties of IN esketamine. Clinical studies specifically investigating cognition as a primary outcome measure of IN esketamine in TRD are warranted.