Failed Response to Repeat Intravenous Ketamine Infusions in Geriatric Patients With Major Depressive Disorder

Abstract

Geriatric depression has reported prevalence rates of 1.6 to 15% of the population1. New effective fast-acting treatment modalities in this population would be cost saving and alleviate suffering and disability for the patients and their families. The rapid onset of antidepressant effect produced by subanesthetic intravenous (IV) ketamine provides such a promise. Single2, 3 and repeat 4-7 ketamine infusions have been shown to produce an antidepressant effect within hours with a sustained effect lasting days to weeks. But not all depressed patients who are administered ketamine have a response. Using a 50% reduction in baseline symptoms as the response criteria, response rates of 43-90% are reported within 40 minutes, 24 hours, and 72 hours post-infusion8. Although a large number of patients do respond, studies to accurately predict who responds are at an early stage. Here, we report a case series where IV ketamine infusions in geriatric patients with Treatment Resistant Depression (TRD) did not prove beneficial. Four patients (mean (± SD) age, 72.25 (± 5.38) years) admitted to an inpatient psychiatric unit due to a relapse in their Major Depressive Disorder (MDD), with histories of multiple failed medication trials and failed electroconvulsive therapy (ECT), were offered IV ketamine treatments, as described elsewhere9. An Institutional Review Board approved retrospective chart review was conducted for this case series. After the initial inpatient infusion demonstrated no physiological concerns, the infusions were continued on an outpatient basis. Prescribed medications were continued throughout the infusions.