Psychedelics
June 28, 2026
Joost J. Breeksema, Ulf Bremberg, Jens H van Dalfsen et al.
Psychedelic therapies face layered complexity from interactions between pharmacological and extra-pharmacological factors, and their embeddedness in societal, legal, and regulatory systems. This is compounded by epistemic fragmentation: dominant biomedical paradigms often clash with knowledge from social sciences, humanities, or Indigenous traditions. Though interdisciplinary engagement is increasingly recognized as necessary, existing calls rarely specify structural or pedagogical conditions for operationalizing it. Addressing these complexities requires moving beyond superficial collaboration; genuine interdisciplinary progress needs researchers capable of productive friction across epistemic cultures. The authors propose cultivating T-shaped competencies and intersectoral training as a structural response to these systemic challenges.
Journal of Psychiatric Research
June 12, 2026
Juliana Lima Constantino, Tobias Stephan Freimann, Jens H van Dalfsen et al.
Oral esketamine can be an effective and well-tolerated treatment for treatment-resistant depression (TRD), but about half of those treated do not respond. This study tested whether sociodemographic and clinical features, including depressive symptoms and treatment resistance, could predict how much depressive symptoms would improve in 131 TRD patients receiving individually adjusted oral esketamine doses (0.5 mg/kg to 3 mg/kg) twice weekly for six weeks. Machine learning models—linear regression, elastic net, and random forest—failed to predict symptom change above chance. The findings suggest that oral esketamine may work similarly across the TRD population, regardless of treatment-resistance levels.
The pharmacogenomics journal
April 24, 2026
Daniël T Coerts, Sanne Y Smith-Apeldoorn, Jérôme C Oude Nijhuis et al.
A genetic variation in the CYP2B6 enzyme, known as 516 G > T, is linked to higher blood levels of oral esketamine four hours after dosing in people with treatment-resistant depression. In a small sample of 18 participants from a placebo-controlled trial, carriers of the variant had median esketamine levels of 5.1 µg/L, compared to 2.1 µg/L in non-carriers. No significant associations were found for two other genetic variants, CYP3A4*22 and CYP3A5*3, but the numbers of carriers were very small. Larger studies are needed to clarify their effects.
Pharmacogenomics
December 12, 2025
Jérôme C Oude Nijhuis, Daniël T Coerts, Jens H van Dalfsen et al.
Oral esketamine is a promising treatment for depression that does not respond to other therapies, but how much of the drug reaches the bloodstream varies from person to person. This study tested whether common genetic variations in two drug-transport proteins, ABCB1 and ABCG2, affect esketamine levels in the blood. In 18 participants from a placebo-controlled trial, esketamine concentrations four hours after dosing did not differ significantly among people with different ABCB1 or ABCG2 genotypes. Metabolite levels also showed no association with these genetic variants. The findings suggest that these transporter polymorphisms do not influence oral esketamine pharmacokinetics, though the small sample size means the results are preliminary and need confirmation in larger studies.
J Affect Disord
October 10, 2025
Guy M. Goodwin, Scott T Aaronson, Oscar Alvarez et al.
correction
No Summary
Clinical psychopharmacology and neuroscience : the official scientific journal of the Korean College of Neuropsychopharmacology
August 31, 2025
Cagdas Türkmen, Rutger Boesjes, Anne-Fleur Zandbergen et al.
In adults with treatment-resistant depression, intranasal esketamine added to an antidepressant does not change the likelihood of experiencing insomnia as a side effect compared with placebo. Across seven randomized trials involving 1,311 patients, insomnia was reported by 7.3% of those receiving esketamine and 6.7% of those receiving placebo, a difference that was not statistically significant. This finding contrasts with earlier reports that esketamine improves insomnia symptoms, possibly because adverse-event reporting does not capture gradual improvements in sleep for patients who often have insomnia at the start of treatment.
Journal of Affective Disorders
July 16, 2026
Sara Massetti, Sanne Y Smith-Apeldoorn, Jolien K E Veraart et al.
Ketamine and its enantiomer esketamine are effective in only 30-35% of patients with treatment-resistant depression. Increased serum brain-derived neurotrophic factor (BDNF) after a single intravenous dose has been proposed as a biomarker of antidepressant response, but effects under different treatment schedules are unclear. In a randomized, placebo-controlled trial of six-week, low-dose, oral esketamine (90 mg/day, three 30 mg intakes), depression severity and serum BDNF were measured in 54 patients at baseline, end of treatment, and after a four-week washout. BDNF levels did not significantly differ between esketamine and placebo groups during treatment or washout. An increase in BDNF occurred regardless of treatment condition.
Psychopharmacology
January 1, 2022
Nina Schimmers, Joost J. Breeksema, Sanne Y Smith-Apeldoorn et al.
Both classical psychedelics (DPT, LSD, psilocybin) and atypical psychedelics (MDMA, ketamine) show promise for reducing anxiety, depression, and existential distress in terminally ill patients, with recent controlled trials indicating positive effects on existential and spiritual well-being, quality of life, and acceptance while causing few adverse and no serious adverse effects. Early studies had serious methodological flaws, but newer trials are of higher quality. Larger high-quality studies are still needed for classical psychedelics and MDMA, and ketamine research should better address existential well-being and psychotherapeutic context.
BMC Psychiatry
November 29, 2019
Sanne Y Smith-Apeldoorn, Jolien K E Veraart, Jeanine Kamphuis et al.
A triple-blind randomized placebo-controlled trial investigates daily oral esketamine versus placebo as an add-on to regular antidepressants in patients with treatment-resistant depression over 6 weeks, followed by a 4-week follow-up. This is the first such trial to examine the efficacy, safety, tolerability, mechanisms of action, and economic impact of repeated oral esketamine administration. If effective and tolerated, oral esketamine offers practical advantages over intravenous administration. The study aims to address the urgent need for additional treatment strategies for treatment-resistant depression.