Antianhedonic effects of serial intravenous subanaesthetic ketamine in anxious versus nonanxious depression

Abstract

ObjectivesPatents with anxious depression have poor treatment outcomes compared to their nonanxious counterparts. Ketamine has a rapid and robust antianhedonic effect, independent of depressive symptoms. The difference in the antianhedonic effect of ketamine between patients with anxious versus nonanxious depression remains unknown. MethodsOne hundred thirty-five Chinese individuals with anxious depression (n = 92) and nonanxious depression (n = 43) received six intravenous infusions of ketamine (0.5 mg/kg). Post hoc analyses compared changes in anhedonic symptoms, as measured by the Montgomery–Åsberg Depression Rating Scale (MADRS), between patients with anxious depression (defined by a Hamilton Depression Rating Scale Anxiety-Somatization score ≥7) and nonanxious depression. ResultsIn this study, 68.1 % of patients were found to have anxious depression. Anxious depressed patients were associated with a relatively lower antianhedonic response (47.8 % versus 51.2 %, p > 0.05) and remission (17.4 % versus 27.9 %, p > 0.05) than their nonanxious counterparts. When compared to baseline, a significant reduction in anhedonic symptoms was observed from the first infusion to the last infusion and 2-week follow-up in both groups (all p < 0.05). A linear mixed model did not find a significant group main effect on the MADRS anhedonia subscale scores (F = 0.5, p = 0.46). ConclusionThis preliminary study shows that repeated intravenous infusions of ketamine rapidly ameliorate anhedonic symptoms in individuals experiencing anxious depression, but these individuals displayed a weaker antianhedonic response to ketamine than nonanxious depressed patients.