Acute and long-term effects of repeated ketamine infusions in treatment-resistant depression and associated metabolite changes.
Psychiatry and clinical neurosciences – July 15, 2025
Source: PubMed
Summary
Predicting how well someone with severe depression will respond to treatment might be possible early on. Researchers explored if repeated ketamine infusions could help those with treatment-resistant depression. They found these infusions rapidly improved symptoms, with some patients achieving sustained relief. Crucially, changes in a specific metabolite, 3-hydroxybutyrate, measured via metabolomics after the first ketamine dose, predicted long-term improvements in depression. This suggests a powerful way to personalize future depression care.
Abstract
This study aims to investigate the acute and sustained antidepressant effects of repeated ketamine infusions in patients with treatment-resistant depression (TRD), and to identify early metabolomic changes predictive of treatment outcomes using metabolome analyses. This open-label study investigated the effects of four intravenous ketamine infusions (0.5 mg/kg) administered over 2 weeks in 30 patients with TRD. Clinical outcomes, including the Montgomery-Åsberg Depression Rating Scale (MADRS), were evaluated at baseline, 1-2 h after each infusion, and monthly during a 12-month follow-up. Plasma levels of 11 depression-associated metabolites were measured at baseline and 1.5-2 h after the first infusion. A general linear model was employed to analyze the association between metabolite changes after the first infusion and the MADRS score percent improvements after the fourth infusion and at 12 months. Remission was defined as a MADRS score of ≤10. All participants completed the four infusions. The MADRS score decreased from 30.6 ± 6.1 at baseline to 20.3 ± 11.5 after the fourth infusion, with a remission rate of 26.7%. At 12 months, 13.3% of participants remained in remission. Changes in 3-hydroxybutyrate levels after the first infusion predicted the MADRS score percent improvements after the fourth infusion (β = 1.35, 95% CI: 0.41-2.30, P = 0.005) and at 12 months (β = 1.38, 95% CI: 0.37-2.39, P = 0.007). While repeated ketamine infusions demonstrated rapid antidepressant effects, sustained remission was achieved in a minority of patients with TRD. 3-Hydroxybutyrate may serve as a biomarker for predicting treatment response. These findings underscore the potential for individualized strategies using ketamine infusions. jRCTs031210648 (Japan Registry of Clinical Trials).