Translated from our German original by AI. The German text was researched, written, and edited by the Psychedelia Foundation team and remains the authoritative version.
A small observational study of inpatients with treatment-resistant depression offers indications of which factors could be linked to a lack of improvement in anhedonia under ketamine treatment. Anhedonia, the reduced capacity to feel pleasure or interest, is considered a core symptom of severe depression and is associated with a higher burden of illness, poorer everyday functioning, and an increased risk of suicide.
For the retrospective analysis, researchers evaluated data from 34 patients with treatment-resistant major depression who received ketamine over four weeks in addition to standard treatment, either intravenously or orally. The analysis looked at which clinical and social characteristics were linked to a response in the anhedonia symptoms. Treatment success was defined as an improvement of at least 50 percent on the Snaith-Hamilton Pleasure Scale (SHAPS), an established instrument for measuring anhedonia.
The evaluation showed that 16 of the 34 patients, around 47 percent, did not reach this improvement. Notable differences between responders and non-responders appeared above all in three areas. Patients without a clear improvement in anhedonia had a lower rate of substance use disorders in their history, reported fewer depressive episodes over the course of their illness, and were more often single.
A statistical model that took these three factors into account together proved significant overall. No differences were found between intravenous and oral ketamine administration; the distribution of both forms of treatment was comparable across the groups.
The authors stress that the results have to be interpreted cautiously given the small sample and the retrospective design. The data did suggest, however, that psychosocial factors and individual illness trajectories could play an important role in how anhedonia symptoms respond to ketamine. This, they write, underlines the importance of personalized treatment approaches in treatment-resistant depression.
