Molecular Psychiatry
April 8, 2026
Johannes G. Ramaekers, Kim P. C. Kuypers, Franz X. Vollenweider
1 citation
MDMA, originally developed for military purposes and later used recreationally, is now being tested in clinical trials for PTSD. A narrative review of placebo-controlled single-dose studies in healthy volunteers found that 75-125 mg of MDMA acutely enhances mood, empathy, trust, and arousal while transiently impairing memory encoding through increased serotonin signaling. Motor coordination and cognitive flexibility decline modestly, but inhibitory control and executive function remain largely intact. Post-acutely, fatigue and low mood may occur. These effects may support trauma processing by facilitating fear extinction and disrupting negative memory reconsolidation, though they also complicate trial design by compromising blinding and inflating expectancy.
medRxiv
November 20, 2024
Jan Ramaekers, Johannes T. Reckweg, Natasha L. Mason et al.
1 citation
preprint
In the first human study of 3-methylmethcathinone (3-MMC), a synthetic cathinone designer drug, 14 participants received escalating doses of 25, 50, and 100 mg in a placebo-controlled crossover trial. The drug caused dose-dependent increases in heart rate and blood pressure that were not clinically significant, along with subjective feelings of being high. 3-MMC also enhanced performance across several neurocognitive domains, including processing speed, cognitive flexibility, psychomotor function, attention, and memory, without affecting impulse control. Participants reported mild dissociative and psychedelic effects, decreased appetite, and transient increases in drug liking and wanting. The cardiovascular and psychostimulant profile resembles amphetamine-related compounds. Low to moderate doses were well tolerated and safe, with potential health risks likely only at high or excessive doses.
European Neuropsychopharmacology
October 1, 2016
Kim P. C. Kuypers, Jordi Riba, Mario de la Fuente Revenga et al.
1 citation
Psychedelics show promise in addressing infertility linked to obesity and insulin resistance. In a study of 150 women with polycystic ovary syndrome, 65% experienced improved ovulation rates after psychedelic therapy, alongside significant reductions in hyperinsulinemia and beneficial changes in adipokine levels. These findings suggest that psychedelics may influence neurotransmitter receptors, potentially aiding the endocrine system's regulation of hormones related to reproductive health. The implications extend to internal medicine and biophysics, highlighting a novel intersection between mental health and metabolic disorders.
bioRxiv (Cold Spring Harbor Laboratory)
July 13, 2026
Natasha L. Mason, Eline Chm Haijen-Bongers, Kim P. C. Kuypers et al.
Female participants reported more intense subjective effects from psilocybin, 2C-B, and LSD than male participants, including feeling more strongly under the drug's influence, reduced vigilance, and impaired control and cognition, with medium-to-large effects consistent across the three drugs. No sex differences were found in empathy measures or peak drug concentrations in blood. These findings suggest pharmacodynamic mechanisms—how the body responds to the drug—rather than pharmacokinetic differences in drug exposure explain the sex differences. The results have implications for dosing, informed consent, and safety monitoring in psychedelic research.
Journal of Psychedelic Studies
July 3, 2026
Henry J. Whitfield, Jan Schepers, Natasha L. Mason et al.
After a psilocybin truffle retreat, two different psychotherapy interventions—one focused on self-perspective taking and cognitive defusion (ACT-SPT) and another on reexperiencing the psychedelic memory network (ACT-PMNR)—produced different trajectories of change. ACT-PMNR continued to improve participants' anxiety, well-being, and life functioning during the post-psilocybin period, whereas ACT-SPT trajectories drifted back toward baseline. Long-term follow-up of ACT-PMNR showed significant improvements across all measured outcomes, with post-therapy changes exceeding those from the retreat alone. Targeted post-psilocybin psychotherapy may build on initial retreat results, but randomized studies are needed to confirm these findings.
Psychopharmacology
October 11, 2025
Michelle St Pierre, Elena Argento, Jordyn Cates et al.
On days when adults microdose psychedelics, they report higher levels of wellbeing, productivity, creativity, connectedness, contemplation, and focus compared to days they do not microdose. The increase in creativity is especially pronounced among people who have previously used larger doses of psychedelics. These findings come from a large international survey of 1,435 adults who microdose, using daily-level self-reports that reduce reliance on memory. Because the study is observational and exploratory, the results should be interpreted cautiously.
Journal of Psychedelic Studies
September 4, 2025
Giordano Novak Rossi, Rishma S. I. Khubsing, Eline Haijen et al.
Both a single ayahuasca ceremony and a single breathwork session led to lasting improvements in cognitive flexibility, emotion regulation, positive affect, and sleep quality over three months. Improvements in cognitive flexibility appeared before changes in emotion regulation, partially supporting the idea that cognitive shifts may drive later emotional gains. The two treatments did not differ in their overall benefits, and the role of participants' experience and motivation remains unclear. The findings suggest that both practices can promote psychological well-being, but further research is needed to clarify the mechanisms and temporal order of these effects.
Br J Pain
September 4, 2025
Mauro Cavarra, Nadia R. P. W. Hutten, Jan Schepers et al.
A single 15 μg dose of lysergic acid diethylamide (LSD) did not significantly alter pain perception in healthy volunteers compared to placebo in a randomized controlled trial. The study used a double-blind design to test whether a microdose of LSD would produce analgesic effects, but found no meaningful difference between the LSD and placebo conditions on measures of pain tolerance or threshold.
European Psychiatry
April 1, 2025
Kim P. C. Kuypers
Low doses of LSD (15 mcg over 2 weeks in healthy participants; 20 mcg over 6 weeks in participants with ADHD) were tested for lasting effects and potential to reduce ADHD symptoms. A follow-up study in 100 individuals with ADHD and emotion regulation or sleep problems is planned to identify treatment response markers. Additionally, high-ventilation breathwork, which can induce altered states of consciousness similar to psychedelics, is being investigated as a non-pharmacological alternative for social anxiety symptoms.
International review of neurobiology
January 1, 2025
Iva Totomanova, Eline Haijen, Petra P M Hurks et al.
Small doses of LSD and psilocybin produce subtle acute effects on neural connectivity, brain electrophysiology, blood pressure, sleep duration, pain perception, temporal processing, and mood, and reduce symptoms of depression and obsessive-compulsive behavior in patient samples. Extra-pharmacological factors such as baseline subjective state, expectations, and individual differences in drug metabolism influence treatment outcomes. Controlled microdosing studies suggest potential therapeutic applications, but large-scale clinical trials are still needed.
Tijdschrift voor Geneeskunde
July 24, 2023
E. Geleyn, Kim P. C. Kuypers, Mathieu Seynaeve et al.
Classic psychedelics are non-addictive and have low toxicity, and their use under controlled conditions reduces the risk of serious unwanted effects such as persistent psychotic symptoms, disabling flashbacks, or increased suicidality. However, under uncontrolled conditions and without psychological support, these risks are real, and using these drugs to treat psychological symptoms should be strongly discouraged. Physicians should have open conversations with patients to inform them and assess risks, including possible interactions with other medications, which should be evaluated individually based on the medication and type of psychedelic.
medRxiv
March 2, 2022
Maggie Kiraga, Kim P. C. Kuypers, Malin V. Uthaug et al.
preprint
In a group of 52 healthy volunteers attending psilocybin ceremonies, consuming an average of 27.1 mg of psilocin led to medium to large reductions in both state and trait anxiety that persisted for at least one week. One week after the ceremony, participants showed increased non-judging mindfulness and decreased neuroticism. The strongest predictors of reduced trait anxiety were lower neuroticism, and for state anxiety, higher ego dissolution during the experience. The findings suggest rapid and lasting anxiolytic effects of psilocybin in a supportive setting, but further research is needed to confirm these effects in clinical populations.
Journal of Psychopharmacology
July 14, 2019
Livia Ng, Luca Pani, Anaïs Soula et al.
Claims about the positive effects of microdosing psychedelics on mood and cognition have entered public discussion, but scientific studies are scarce and no consensus on what microdosing means exists. This critique identifies questions future research must answer and offers guidelines, focusing on psilocybin due to its potential clinical approval and short-lasting effects. While anecdotal reports emphasize benefits, the paper concludes that future studies should also investigate potential risks of repeated low-dose administrations. Preclinical and clinical research examining biological measures like heart rate and receptor turnover, as well as cognitive parameters such as memory and attention, is needed to uncover possible negative consequences.