A comparison of the antianhedonic effects of repeated ketamine infusions in melancholic and non-melancholic depression.

Abstract

Melancholic depression may respond differently to certain treatments. The aim of this study was to compare the antianhedonic effects of six intravenous injections of 0.5 mg/kg ketamine in patients with melancholic and non-melancholic depression, which remain largely unknown. Individuals experiencing melancholic (n = 30) and non-melancholic (n = 105) depression were recruited and assessed for anhedonic symptoms using the Montgomery-Åsberg Depression Rating Scale (MADRS). The presence of melancholic depression was measured with the depression scale items at baseline based on DSM-5 criteria. A total of 30 (22.2%) patients with depression fulfilled the DSM-5 criteria for melancholic depression. Patients with melancholic depression had a non-significant lower antianhedonic response (43.3 vs. 50.5%, t = 0.5, p > 0.05) and remission (20.0 vs. 21.0%, t = 0.01, p > 0.05) to repeated-dose ketamine infusions than those with non-melancholic depression. The melancholic group had significantly lower MADRS anhedonia subscale scores than the non-melancholic group at day 26 (p < 0.05). After six ketamine infusions, the improvement of anhedonic symptoms was found in both patients with melancholic and non-melancholic depression, and the efficacy was similar in both groups.