Psychedelic Research Papers

This meta-analysis (s=29) examines the effects of psychedelics (including ketamine and MDMA) and two other 'psychoplastogens' on peripheral BDNF levels in humans. It finds no significant changes in BDNF levels post-administration (SMD=0.024, p=0.64), regardless of drug, dose, participant age, or psychiatric condition. Studies with better-controlled designs report smaller effect sizes, and later timepoints show minimal increases in BDNF. The authors conclude that peripheral BDNF is likely not a reliable marker of rapid neuroplasticity and recommend neuroimaging or stimulation-based methods for future research.

This review (2024) highlights preclinical research from the past 15 years showing that ketamine and psychedelics trigger dendritic spine growth in cortical pyramidal neurons, enhancing neural plasticity. It compares the longitudinal effects of psychoactive drugs, emphasizing rapid-onset and sustained structural plasticity as key features of rapid-acting antidepressants, and discusses gaps in understanding and prospects for other interventions like rTMS.

This subgroup analysis of a trial on treatment-resistant depression (n=4) evaluates the safety and efficacy of psilocybin (25 mg) in individuals with Bipolar II disorder. Results show a reduction in MADRS scores from 32.5 at baseline to 21.3 at 6 months, with no emergent mania, hypomania, or psychosis, suggesting potential improvement in depressive symptoms.

This pre-print cross-over, placebo-controlled trial (n=14) assesses the effects of escalating doses of 3-MMC (25, 50, 100mg) on vital signs, neurocognitive function, state of consciousness, appetite, and drug desire. Results show dose-dependent increases in heart rate and blood pressure (not clinically significant), enhanced neurocognitive task performance, and mild dissociative and psychedelic effects. Participants reported decreased appetite and transient increases in liking and wanting 3-MMC. Low to moderate doses were well tolerated and safe, with potential risks associated with high doses.

This pooled analysis of two RCTs (n=48) investigates the safety of mescaline in single oral doses of 100–800 mg (96 administrations). Positive subjective effects increased dose-dependently, while autonomic effects were moderate. Adverse effects, including nausea (dose-limiting), were recorded, but no significant issues with liver/kidney function or blood cell counts occurred. "Flashbacks" were reported in 2% of administrations. Mescaline doses up to 800 mg were deemed safe in a controlled clinical setting for healthy participants.

This pharmacokinetic study (n=16 + n=51 data from earlier study) investigates the effects of food on MDMA pharmacokinetics and uses population and physiologically based pharmacokinetic models to simulate clinical dosing regimens. Results show that a high-fat/high-calorie meal delays Tmax but does not alter plasma concentrations, with no clinically meaningful covariates identified. Simulations reveal MDMA is a potent CYP2D6 inhibitor but has negligible impact on drugs sensitive to renal transport, informing drug–drug interaction potential and dosing strategies.

This systematic review (2024) and meta-analysis (s=131) examines the incidence of psychedelic-induced psychosis, focusing on individuals with schizophrenia. It finds an incidence of 0.002% in population studies, 0.2% in UCTs, and 0.6% in RCTs, with 3.8% of UCT participants with schizophrenia developing long-lasting psychotic symptoms. It also reports that 13.1% of those with psychedelic-induced psychosis later developed schizophrenia.

This survey (n=581) evaluates the Psychedelic-related Major Life Changes Questionnaire (P-MLCQ) in people reporting naturalistic psychedelic use. It finds that 82.96% of participants reported major life changes in at least one domain, including goals (53.7%), values (53.53%), and spirituality (49.05%), with changes rated highly positively (M = 4.64/5). Frequency of use correlated with more changes (r = 0.34), while education level was negatively associated with the number of changes (β = -0.137).

This mixed-methods investigation (n=16 psilocybin retreat participants; n=529 online survey respondents) explores strategies for navigating challenging psychedelic experiences and their link to emotional breakthroughs. Three primary strategies—Acceptance and Reappraisal, Sensory Regulation and Physical Interaction, and Social Support and Disclosure—emerged, with the first and third positively associated with emotional breakthroughs. Fear-related challenges were negatively associated with breakthroughs, indicating the need for adaptive coping strategies to optimize therapeutic and safety protocols.

This theoretical framework paper analyses two Phase III trials of MDMA-assisted therapy for PTSD, describing the conceptual underpinnings and therapeutic approach. It explains how the treatment combines three MDMA-facilitated sessions with non-drug psychotherapy sessions, emphasizing the patient's "inner healing intelligence" as the primary change agent and the therapeutic relationship as the core facilitating condition.

This reanalysis of four RCTs (n=96) finds that MDMA (100mg or 125mg) induced hyponatremia in 31% of participants, with none occurring in the fluid-restricted group (n=15) compared to 37% in the unrestricted group (n=81). The study challenges previous understanding by showing hyponatremia correlates with increased oxytocin (433% increase) rather than vasopressin levels, suggesting oxytocin mimics vasopressin's effects in the kidneys.

This meta-analysis (s=5, n=158) of classic psychedelic effects on empathy using the Multifaceted Empathy Test (MET) finds significant enhancement of explicit and implicit emotional empathy, with no effect on cognitive empathy. The analysis covers studies up to November 2023 examining LSD, psilocybin, and ayahuasca.

This placebo-controlled study (n=6) investigates how psilocybin (25mg) affects visual surround suppression compared to placebo (100mg niacin). The study finds increased surround suppression effects under psilocybin, with stronger suppression correlating with more intense subjective visual effects.

This online survey (n=6,193; 2,488 microdosers) examines differences between exclusive microdosers and those who use both micro and macrodoses of psychedelics. The study finds exclusive microdosers were typically older, more likely to be female and non-Caucasian, with psilocybin (74.5%) and LSD (34.4%) being the most commonly used substances, primarily for general wellbeing (73.0%).

This cost-effectiveness analysis compares MDMA-assisted therapy (MDMA-AT) versus placebo with therapy (PT) for chronic PTSD treatment over 5 years. Using a health state-transition model, it finds MDMA-AT to be cost-effective with an ICER of $83,845 per QALY (below the $150,000 willingness-to-pay threshold), despite higher intervention costs ($48,376 vs $12,376), due to reduced healthcare visits and better health outcomes (0.377 QALY increment).

This pre-print mouse study investigates how psilocybin affects different types of brain cells in the medial frontal cortex (mPFC; decision-making processes and judgement). The research finds that psilocybin increases dendritic spine density in both pyramidal tract (PT) and intratelencephalic (IT) neurons, but only PT neurons are essential for psilocybin's anti-stress effects through 5-HT2A receptor activation.

This randomised feasibility study (n=37) evaluates psilocybin-assisted (microdoses x 6) frontal-midline theta neurofeedback (NF) to improve executive functions (EFs) in participants with psychiatric disorders. Despite no significant improvements in tasks-based EFs, the experimental group reported medium to high gains in daily EFs, indicating the potential benefits of this neuromodulation technique for enhancing daily functioning.

This lab study used different ways of looking at cells to see how the psychedelic drug DOI affects the outer layer of cells (lipid membrane). The study found that DOI is over 100 times stronger than serotonin at disrupting the cell's outer layer, helping small bubble-like structures combine with cells, and making it easier for tiny holes to form in cell membranes. This suggests that psychedelics might affect the brain not just by binding to receptors (their usual known method), but also by physically changing how cell membranes work and help create new connections.

This pre-print, open-label, proof-of-concept trial (n=5) of psilocybin-assisted therapy for fibromyalgia finds the treatment to be well-tolerated, with only transient blood pressure elevations and headaches reported. Secondary outcomes show clinically meaningful improvements in pain severity, pain interference, and sleep disturbance one month after treatment, with all participants reporting some degree of symptom improvement.

This pre-registered randomized placebo-controlled study (n=34) investigates the effects of MDMA (100mg) administration on personality traits and affective states in healthy adults. While no statistical significance was found for the primary hypotheses, medium effect sizes were observed for increased Openness (d = 0.79) and Positive Affect (d = 0.51) 48 hours after MDMA administration compared to placebo.

This internet survey (n=629) examines how psychedelic experiences relate to psychological flexibility and mental well-being in classical psychedelic users. Network analysis shows psychological insight links to acceptance, while mediation analysis reveals psychological flexibility mediates the relationship between psychedelic use and well-being, suggesting experience quality matters more than frequency of use.

This survey study (n=457) explores the relationship between dysfunctional attitudes and well-being in the context of psychedelic-assisted therapy. It finds that post-acute changes in these attitudes significantly influence well-being, with emotional breakthroughs having a greater impact than challenging or mystical experiences.

This post hoc analysis (n=233) of a Phase II RCT investigates the impact of recent antidepressant discontinuation (n=156) on the efficacy of psilocybin in treating treatment-resistant depression (TRD). The study compares outcomes between participants who discontinued antidepressants during screening and those who entered the trial free of these medications, finding no significant relationship between antidepressant discontinuation and worsening depression severity or compromised psilocybin treatment efficacy.

This preprint mouse study (n=29) finds that the serotonin 1B receptor (5-HT1BR) is necessary for psilocybin's antidepressant and anxiolytic effects, independent of its hallucinogenic properties. Using transgenic mice lacking 5-HT1BR and network analysis, the study demonstrates that this receptor influences brain-wide activity patterns and mediates acute and persistent behavioural responses to psilocybin, suggesting a novel mechanism for psilocybin's therapeutic effects.

This retrospective analysis (n=841) of the Prehospital Tranexamic Acid Use for Traumatic Brain Injury trial evaluates the effects of ketamine in subjects with traumatic brain injury (TBI). It finds no significant difference in mortality or disability between ketamine-exposed (15.5%) and unexposed subjects, though ketamine exposure was associated with fewer instances of elevated intracranial pressure and a lower increase in TBI protein biomarkers, despite a higher likelihood of seizure activity in the ketamine group.

This pre-print, double-blind, placebo-controlled crossover study (n=22) investigates the neural effects of 2C-B (20mg) compared to psilocybin (15mg) and placebo using 7T resting-state functional MRI. The results reveal that both 2C-B and psilocybin reduce intra-network connectivity while enhancing between-network connectivity, with 2C-B showing less impact on certain connectivity measures but greater transmodal connectivity.

This online survey (n=233) of autistic participants with high autism quotient scores examines their experiences with psychedelic drugs and perceived changes attributed to their most 'impactful' psychedelic experience. It finds that the majority of participants reported reductions in psychological distress (82%) and social anxiety (78%), and increases in social engagement (70%), while 20% reported undesirable effects such as increased anxiety.

This preprint, naturalistic EEG study (n=29) examines the effects of inhaled synthetic 5-MeO-DMT (12mg) on brain activity in healthy individuals. It finds that 5-MeO-DMT radically reorganises low-frequency neural activity flows, making them incoherent, heterogeneous, and nonrecurring. It also causes broadband activity to exhibit slower, more stable, low-dimensional behaviour with increased energy barriers to rapid global shifts.

This meta-analysis (2024, s=31) examines the correlation between subjective effects and therapeutic outcomes for ketamine (s=23, n=471) and psilocybin (s=8, n=183) in depression and substance use disorder (SUD) treatment. It finds modest mediating effects of subjective experiences on therapeutic outcomes, with psilocybin showing a stronger mediating effect (R² = 24%) compared to ketamine (R² = 5-10%), and a greater mediating effect observed in SUD compared to depression regardless of the substance used.

This preprint open-label study (n=20) examines the effects of ketamine infusions (35mg/70kg, 6x) on biological ageing markers in individuals with depression (MDD) or PTSD. It finds reductions in epigenetic age as measured by OMICmAge, GrimAge V2, and PhenoAge biomarkers, as well as significant changes in Epigenetic Biomarker Proxies (EBPs) and surrogate protein markers following a 2-3 week treatment course. The study also reports expected decreases in depression and PTSD scores as measured by PHQ-9 and PCL-5.