What’s Legal, Where — Psychedelic Law in 2026

Compare ketamine and psilocybin for treatment-resistant depression by trial remission, speed, durability, cost per response, and durable-remission-week metrics. Independent technical note mirroring the canonical version: https://aidrugsearch.com/blog/ketamine-vs-psilocybin-for-depression-comparing-speed-and-durability.php

Abstract Major depressive disorder (MDD) is a leading cause of global disability, and a substantial proportion of patients develop treatment-resistant depression (TRD), highlighting the urgent need for mechanistically novel and fast-acting antidepressants. Ketamine has emerged as a paradigm-shifting therapy due to its rapid and robust antidepressant effects, yet its molecular mechanisms in human neurons remain incompletely understood. Here, we investigated the cellular and transcriptomic effects of ketamine in human induced pluripotent stem cell (hiPSC)-derived forebrain neurons. Neuronal cultures were treated with ketamine (1 µM) for 72 h and analyzed using immunocytochemistry, western blotting, and RNA sequencing. Ketamine treatment did not alter gross neuronal morphology or presynaptic organization but significantly increased synaptic localization of the postsynaptic scaffolding protein PSD-95, suggesting molecular changes associated with synaptic remodeling. At the signaling level, ketamine selectively modulated the Akt pathway without inducing changes in BDNF protein levels or MAPK activation, and without broadly altering excitatory or inhibitory synaptic protein expression. Transcriptomic profiling revealed 604 differentially expressed genes, with significant enrichment of pathways related to serotonergic and dopaminergic neurotransmission. Notably, ketamine upregulated genes involved in monoamine synthesis and signaling, including DDC and DRD1 , while downregulating genes associated with GPCR ligand binding and neurotransmitter transport. SynGO analysis further identified selective regulation of synapse-associated genes, predominantly affecting presynaptic and neurotransmitter uptake mechanisms. Together, these findings indicate that ketamine induces molecular and transcriptional changes in human neurons that are consistent with synaptic remodeling and with activation of transcriptional programs enriched for monoaminergic signaling pathways. This hiPSC-based model provides a platform to investigate the molecular responses of human neurons to ketamine and to explore patient-specific mechanisms in future studies.

A nationally representative cross‐sectional survey of U.S. adults found the among all psychedelics, ibogaine and 5‐MeO‐DMT (5‐methoxy‐N,N‐ dimethyltryptamine) resulted in the most frequent self‐reported adverse outcomes, according to a recent study. The study, “Adverse Health Outcomes of Psilocybin, LSD, MDMA, Ibogaine, and 5‐MeO‐DMT,” by Otto Simonsson, Ph.D., and colleagues, was published September 20 in JAMA Network Open. The number of adults reporting adverse outcomes was greatest for psilocybin, LSD (lysergic acid diethylamide) and MDMA (methylenedioxymethamphetamine), because these substances are more commonly used. Many findings have indicated risks of cardiac adverse effects of ibogaine, consistent with its known association with QTc prolongation and arrhythmia. The study researchers said the information is important, as psychedelics such as psilocybin, LSD MDMA are in clinical trials for psychiatric disorders. Ibogaine and 5‐MeO‐DMT have also shown promise for psychiatric disorders in smaller trials. The study's researchers conducted a survey of 1,964 adults. Past 12‐month use was reported by 1,151 respondents for psilocybin, 376 for LSD, 539 for MDMA, 74 for ibogaine and 95 for 5‐MeO‐DMT. The study limitations included the cross‐sectional design, which precluded conclusions about causality.

Public doubt about the usefulness of antidepressants appears to have grown, even as scientific agreement about their efficacy has become more settled. This paper examines the role that figures associated with critical psychiatry have had in promoting this doubt. It traces the long entanglement of antidepressants and their critics over the last eighty years, culminating in a 2022 review of the serotonin hypothesis, which, though it made no claims about efficacy, was widely interpreted as showing that antidepressants do not work. Drawing on Oreskes and Conway's concept of 'manufactured doubt', the paper explores how certain philosophical commitments have shaped these actors' views, at times impeding their engagement with new evidence. In doing so, it marks a distinction between productive and unproductive doubt. Whilst external scrutiny has played a significant role in shaping psychiatry, some positions are held so rigidly that the resulting critiques obscure the scientific consensus and risk undermining psychiatric care.

Objective The molecular mechanisms driving esketamine (ESK) efficacy in the pain-depression dyad (PDD) remain incompletely understood. This study investigated the effects of a sub-anesthetic ESK regimen on cortical expression profiles and exploratory signaling markers within the anterior cingulate cortex (ACC). Methods Male Sprague-Dawley rats were randomized into Sham, PDD, and PDD + ESK groups. The PDD model, established via chronic constriction injury (CCI), was validated using a behavioral test battery tracking mechanical allodynia and depression-like phenotypes. On day 21 post-surgery, PDD + ESK rats received a single esketamine injection (15 mg/kg, i.p.). Multi-regional c-Fos expression mapping across the PFC, HPC, and ACC identified the primary responsive structure, followed by dual immunofluorescence for cellular phenotyping. Finally, ACC excitatory neuronal calcium dynamics, exploratory transcriptomic profiles, and Wnt4-associated molecular alterations (including GSK3β and mTOR phosphorylation alongside synaptic markers) were evaluated using fiber photometry, RNA sequencing, and Western blotting. Results ESK alleviated pain hypersensitivity, behavioral despair, and anhedonia in PDD rats. Regional c-Fos profiling identified the ACC as the primary reactive locus, with activation localized predominantly to CaMKIIα-positive neurons. Fiber photometry confirmed that ESK attenuated functional hyperactivation in these ACC excitatory neurons. Exploratory transcriptomic profiling (unadjusted P < 0.05) revealed candidate altered transcripts, identifying Wnt4 as an exploratory molecular marker for further investigation. Subsequent orthogonal protein validations demonstrated that ESK modulated Wnt4 expression alongside concomitant alterations in GSK3β and mTOR phosphorylation, parallel with the attenuation of pathologically elevated synaptic protein markers and a restorative trend in synaptic ultrastructure. Conclusion A single sub-anesthetic ESK dose effectively alleviates PDD behavioral phenotypes in rats. This therapeutic efficacy is associated with Wnt4-related molecular adjustments coupled with putative downstream GSK3β-mTOR signaling alterations within the ACC CaMKIIα-positive neurons, providing exploratory transcriptomic and molecular insights into cortical adaptations in pain-related affective disorders.

Background Esketamine is a promising therapeutic option for treatment-resistant depression (TRD). Intravenous (IV) administration is the most extensively studied parenteral route. However, subcutaneous (SC) administration may offer simpler, more scalable delivery. Multicenter real-world evidence comparing IV and SC routes of administration remains limited. Objective To report clinical outcomes and tolerability of parenteral esketamine protocols for TRD at three Brazilian advanced-care centers. Methods This multicenter retrospective chart review study (2023–2025) included 72 outpatients aged 18–65 years who received esketamine 2 to 3 times weekly via IV (n = 26; 6 sessions) or SC (n = 46; 12 sessions) administration. Data were analyzed in RStudio 2026.01.0 Build 392 using R 4.5.2. The primary outcome was categorical response on the Beck Depression Inventory-II (BDI-II) at the shared 6-session milestone and at each protocol-specific endpoint. Secondary outcomes included continuous changes in BDI-II and Beck Anxiety Inventory (BAI) scores in the full sample, tolerability and documented adverse events, and exploratory factor analysis of baseline symptom dimensions. Results After six sessions, BDI-II response distribution favored the IV protocol, although the between-group difference was not statistically significant (Pearson’s chi-square = 5.661; p = 0.059; odds ratio, 3.06; 95% CI, 1.22–8.00). At the protocol-specific endpoints, categorical BDI-II response did not differ significantly between groups (Pearson’s chi-square = 1.227; p = 0.541; odds ratio, 1.44; 95% CI, 0.57–3.73). No serious adverse events or adverse-event-related discontinuations were reported; dissociation was more frequent with IV than with SC treatment (53.8% vs. 13.0%; p = 0.001), whereas nausea and mild transient blood pressure increases did not differ significantly. BDI-II factor analysis identified cognitive-affective and somatic-neurovegetative dimensions. Conclusions The IV protocol showed a more favorable BDI-II response distribution at the shared 6-session milestone, whereas SC esketamine achieved statistically comparable categorical outcomes at its 12-session protocol-specific endpoint. Route selection should consider speed of response, tolerability, dosing, operational complexity, and access. SC esketamine may be a feasible option where simplicity, tolerability, and access are priorities. Results should be interpreted with caution because of the retrospective, observational study design.

Ketamine produces rapid antidepressant effects, but the molecular processes associated with their persistence remain poorly defined in humans. We examined longitudinal DNA methylation changes in 10 adults with major depressive disorder undergoing ketamine-assisted psychotherapy using two pre-treatment assessments (T1, T2) and one post-treatment assessment (T3). Participants received three sessions of intranasal racemic ketamine within a structured psychotherapy protocol. Buccal DNA methylation was measured using the Illumina MethylationEPIC v2.0 BeadChip. Depressive symptoms improved markedly following treatment, with mean Beck Depression Inventory–II scores declining from the severe to the mild range (p < .001). Of 802,595 CpG loci evaluated, 20,770 met the nominal T3-versus-T2 screening criterion. Sequential filtering for methylation-change magnitude and movement relative to pre-treatment fluctuation identified 962 retained CpG loci, including 517 retained gene-annotated loci. A supplementary linear mixed-effects analysis modeled repeated measurements within participants across the 603 preselected gene-annotated magnitude-filtered loci; because these loci were selected using the same contrast and cohort, this analysis was not treated as independent confirmation. Exploratory enrichment analysis of this 603-locus set identified NOTCH1-related Reactome terms driven by NOTCH1, DLL1, and ADAM17. Within the retained signature, multiple core and adjacent Notch-related components formed a coherent signaling module spanning ligand, receptor processing, transcriptional regulation, and pathway cross-talk. These findings identify a structured peripheral methylation signature associated with ketamine-assisted psychotherapy. They do not establish brain-specific pathway activation or causality, but provide a longitudinal basis for investigating regulatory adaptations accompanying clinical improvement.