Ketamine treatment for depression in elderly inpatients: an observational case series

• This open-label trial assessed the tolerability, safety, and potential clinical benefits of repeated intravenous ketamine infusions in geriatric treatment-resistant depression in a real-world inpatient setting. • The treatment was generally well tolerated with no discontinuation due to adverse effects. • 70 % of patients showed clinically significant improvements. • Antidepressant effects were mostly short-lived. Treatment-resistant depression (TRD) in elderly patients is a challenging issue, with limited options beyond electroconvulsive therapy (ECT). Intravenous ketamine has emerged as a potential alternative, but its efficacy in older patients is not well-studied. This study evaluates the tolerability and efficacy of intravenous ketamine in 10 consecutively treated elderly patients mostly with TRD in an inpatient geriatric psychiatry setting. Ten elderly patients (aged 61–77) mostly with TRD were treated with six bi-weekly intravenous ketamine infusions (0.5–1.0 mg/kg) as an add-on treatment in an open-label trial. Depression severity was assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS) at baseline, after two treatments, and after six treatments. Clinically significant improvement (≥25 % improvement), response (≥50 % improvement), and remission (MADRS < 10) rates were calculated. Tolerability was monitored throughout. After six treatments, 7 out of 10 patients showed clinically significant improvement, with 5 meeting response criteria, and 2 achieving remission. The mean MADRS score reduction was 14.2 (SD = 9.62) for the entire sample. Those with ≥25 % improvement exhibited a rapid decrease in symptoms, with a mean MADRS score reduction of 14.14 (SD = 6.74) already after the second infusion. Only 2 of the 7 patients showed sustained benefit four weeks after treatment. The treatment was well-tolerated with no serious adverse events. Intravenous ketamine rapidly reduced depressive symptoms in most patients, but the majority did not maintain the response at four-week follow-up. Further research is needed to develop strategies for maintaining the effects and to study larger samples.