Anhedonia and depression severity measures during ketamine administration in treatment-resistant depression.

Anhedonia, a reduced ability to experience pleasure, is a core depression symptom that often persists despite standard treatments. Ketamine appears to have antianhedonic effects. In a naturalistic study of 28 inpatients with treatment-resistant depression, both responders and non-responders to ketamine therapy showed significant reductions in anhedonia over time, as measured by the Snaith-Hamilton Pleasure Scale. Non-responders also reported significant improvement in self-reported depression at the seventh infusion, but not at follow-up. Changes in depressive symptoms and anhedonia did not fully overlap, suggesting ketamine may alleviate anhedonia as a separate symptom domain regardless of overall treatment response.

Study at a glance

Abstract

Anhedonia is a core symptom of depression characterized by a diminished ability to experience pleasure. Currently available treatments for depression often fall short in adequately addressing anhedonia that often presents as a chronic and debilitating symptom. Ketamine is known to possess antianhedonic properties. This post-hoc analysis of a naturalistic observational study of treatment-resistant depression inpatients (n=28) analyzed antianhedonic response patterns measured by Snaith-Hamilton Pleasure Scale and changes in Inventory of Depressive Symptomatology in responders (n=6) and non-responders (n=22) stratified per Montgomery-Åsberg Depression Rating Scale during short-term ketamine treatment. Results show that responders significantly improve in anhedonia over time (p=0.0084) and at the 7th infusion and follow-up (both p<0.05). Non-responders reported significant reduction in anhedonia over time (p=0.0011) and at the 5th, 7th infusion and at the follow-up (all p's<0.05). Non-responders were also observed to improve significantly in self-reported depression at the 7th infusion (p=0.0219) but not at the follow-up. There is no complete overlap between change in depressive symptoms and anhedonia. Therefore, it might be assumed ketamine alleviates anhedonia as an individual symptom domain regardless of formal treatment outcome.