Anhedonia nonresponse to short-term ketamine administration for treatment-resistant bipolar depression.

Anhedonia, a core symptom of bipolar depression, often fails to improve with ketamine treatment in patients with treatment-resistant bipolar depression. In a retrospective analysis of 31 patients who received eight doses of ketamine, 45.2% did not achieve a 50% or greater reduction in anhedonia scores. Nonresponders tended to have higher body mass index, later illness onset, fewer hypomanic episodes, and lower employment rates. These metabolic, illness-course, and psychosocial factors may help predict which patients are less likely to benefit from ketamine's anti-anhedonic effects.

Study at a glance

Abstract

Anhedonia is a key symptom of bipolar depression and a target of ketamine's rapid antidepressant effects. However, many patients with treatment-resistant bipolar depression (TRBD) do not respond. This study aimed to identify clinical and sociodemographic characteristics that are associated with nonresponse of anhedonia following short-term ketamine treatment in TRBD. A retrospective analysis using data from two naturalistic, observational registries of 31 patients with TRBD and baseline anhedonia (Snaith-Hamilton Pleasure Scale (SHAPS) > 2). Patients received eight doses of ketamine (IV: 0.5 mg/kg; oral: 2.0-2.5 mg/kg) over a short-term treatment course. Patients were classified as responders or nonresponders based on a ⩾50% reduction in SHAPS score by the seventh ketamine dose. Groups were compared on baseline sociodemographic and clinical features. Fourteen patients (45.2%) did not respond. Nonresponders had higher BMI, later illness onset, fewer hypomanic episodes, and lower employment rates. Metabolic, illness-course, and psychosocial factors may predict reduced anti-anhedonic response to ketamine in TRBD.