Related Experiment Video
Updated: Feb 4, 2026
Vagus Nerve Stimulation As an Adjunctive Neurostimulation Tool in Treatment-resistant Depression
Published on: January 7, 2019
Anhedonia nonresponse to short-term ketamine administration for treatment-resistant bipolar depression
Zofia Kachlik1, Wiesław Jerzy Cubała2, Michał Walaszek2
1Department of Psychiatry, Faculty of Medicine, Medical University of Gdansk, ul. Smoluchowskiego 17, Gdańsk 80-214, Poland.
Background:
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.
Objectives:
This study aimed to identify clinical and sociodemographic characteristics that are associated with nonresponse of anhedonia following short-term ketamine treatment in TRBD.
Design:
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.
Methods:
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.
Results:
Fourteen patients (45.2%) did not respond. Nonresponders had higher BMI, later illness onset, fewer hypomanic episodes, and lower employment rates.
Conclusion:
Metabolic, illness-course, and psychosocial factors may predict reduced anti-anhedonic response to ketamine in TRBD.
Related Concept Videos
01:05Long-term Depression
01:03Long-term Depression
Calcium Ion Concentration Mechanism
If over...
02:56Treatment Resistant Cancers
01:30Bipolar Disorder
03:12Freezing Point Depression and Boiling Point Elevation
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...
01:28Depressants
Alcohol is a common depressant that can induce a sense of relaxation and reduced inhibition at low doses. Contrary to its occasional...