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Journal of Psychopharmacology

SAGE Publications

Preprints posted in the last 90 days, ranked by how well they match Journal of Psychopharmacology's content profile, based on 14 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.

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Distinct Modulatory Effects on Affective Biases by Different Serotonergic Psychedelics and MDMA in Male Rats: Possible Implications for Antidepressant Effects

Hinchcliffe, J.; Bartlett, J.; Thomas, C.; Golden, C.; Bortolotto, Z.; Gilmour, G.; Robinson, E.

2026-04-22 neuroscience 10.64898/2026.04.20.719483 medRxiv
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Affective biases are important neuropsychological mechanisms by which emotions modulate cognition, behaviour and the subjective experience of mood. Previous studies have shown that the rapid-acting antidepressant, ketamine, and serotonergic psychedelic, psilocybin, modulate affective biases in a translational rat model. Both treatments differ from conventional, delayed onset antidepressants in being able to attenuate negatively biased memories and facilitate re-learning with a more positive affective valence. Psilocybin, but not ketamine, also positively biased new experiences, an effect similar to conventional antidepressants. This study used the different affective bias test protocols, in adult male rats, to investigate the effects of acute treatment with the serotonergic psychedelics N,N-DMT, LSD and 5-MeO-DMT, and MDMA. These drugs have different pharmacology in relation to their effects on serotonin receptor subtypes and we hypothesised this may influence their modulation of affective biases. When comparing the ability to attenuate a negatively biased memory, only MDMA had specific effects although for all drugs tested, retrieval of the FG7142-induced negative affective bias was more variable and less robust statistically. LSD attenuated the negative bias at higher doses but had non-specific effects on memory retrieval. At 24hrs post treatment only N,N-DMT had a sustained effect and none of the treatments facilitated re-learning with a more positive affective valence. However, like psilocybin and conventional antidepressants, N,N-DMT positively biased new experiences. These findings suggest there are divergent affective bias modulating effects associated with different psychedelics which may be relevant to their antidepressant effects.

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Acceptability of cannabidiol as a treatment for people at clinical high risk for psychosis

Oliver, D.; Chesney, E.; Wallman, P.; Estrade, A.; Azis, M.; Provenzani, U.; Damiani, S.; Melillo, A.; Hunt, O.; Agarwala, S.; Minichino, A.; Uhlhaas, P. J.; McGuire, P.; Fusar-Poli, P.

2026-03-06 psychiatry and clinical psychology 10.64898/2026.03.05.26347694 medRxiv
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BackgroundAt present, there are no approved pharmacological treatments for people at clinical high risk for psychosis (CHR-P). We sought to assess the acceptability of cannabidiol (CBD): a promising candidate treatment for this population. MethodsCHR-P individuals completed a survey which assessed their views on the acceptability of CBD, its expected effectiveness and side effects, and on formulation preferences. ResultsThe sample comprised 55 CHR-P individuals (24.3 years and 69% female). Most (91%) were familiar with CBD, and had previously used cannabis (64%), and around half (42%) had tried over-the-counter CBD. 75% were willing to take CBD as an intervention for mental health problems. Most participants anticipated fewer side effects with CBD than with existing medications, and preferred tablet or capsule formulations over liquids. DiscussionCBD is perceived as a highly acceptable treatment among CHR-P individuals.

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Mystical Experience Induced by Esketamine Treatment: A Real-World Observational Study

Mallevays, M.; Fuet, L.; Danon, M.; Di Lodovico, L.; Jaffre, C.; Bouzeghoub, L.; Mrad, S.; Rousselet, A.-V.; Allary, L.; Muh, C.; Vissel, B.; De Maricourt, P.; Vinckier, F.; Gaillard, R.; Mekaoui, L.; Gorwood, P.; Petit, A.-C.; Berkovitch, L.

2026-04-01 psychiatry and clinical psychology 10.64898/2026.03.31.26349757 medRxiv
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Esketamine is a fast-acting antidepressant drug which induces acute psychoactive effects. The most frequent is a dissociative state which seems unrelated to therapeutic efficacy. Other esketamine-induced effects, including psychedelic-like mystical experiences, have been poorly studied in terms of phenomenology and frequency, and may carry specific therapeutic relevance. In this study, we characterised esketamine-induced mystical experiences in relation with clinical outcomes. We conducted a longitudinal observational study and systematically measured acute subjective effects in patients receiving esketamine for treatment-resistant depression after each administration across the induction phase. A total of 45 patients were included, from two independent centres, totalling 352 esketamine administrations. Principal Component Analysis (PCA) supported the validity of the Mystical Experience Questionnaire (MEQ-30) for assessing esketamine-induced subjective effects, with components recovering dimensions previously validated with classic psychedelics. Mystical experiences (MEQ-30 score above 60) occurred in 58% of patients, with high inter- and intra-individual variability in frequency, intensity, and phenomenology across sessions. Higher mean and peak MEQ scores were associated with greater improvement in Montgomery-Asberg Depression Rating Scale scores from pre- to post-treatment, whereas the intensity of dissociative or other non-mystical effects was not. Positive mood and mystical MEQ dimensions in particular predicted therapeutic outcomes. Baseline spirituality also significantly predicted treatment outcomes and peak MEQ scores in the first week of treatment. These findings add to the growing body of evidence suggesting that psychedelic-like mystical experiences may be associated to therapeutic efficacy, not only in classic psychedelic-assisted therapy, but also in esketamine treatment.

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When the psychedelic state's over: limited evidence for persistent neurophysiological changes in naturalistic psychedelic users

Wojcik, M.; Orłowski, P.; Adamczyk, S.; Lenartowicz, P.; Hobot, J.; Wierzchon, M.; Bola, M.

2026-04-02 neuroscience 10.64898/2026.03.30.711922 medRxiv
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BackgroundContemporary research indicates that psychedelics induce notable neurophysiological changes, some lasting weeks to months after a single dose. However, most evidence derives from acute administration studies and limited post-acute follow-ups. Long-term naturalistic psychedelic users remain critically underexamined, yet may exhibit distinct neurobiological profiles informing our understanding of persistent alterations following repeated exposure. MethodsWe recorded resting-state EEG in 57 long-term psychedelic users (abstinent [≥]30 days) and 49 matched non-users across two independent sites under eyes-open and eyes-closed conditions. We analyzed oscillatory power, signal complexity, and source-localized effective connectivity, focusing on five canonical frequency bands and regions of the Default Mode, Salience, and Central Executive Networks. Analyses included linear mixed-effects modeling for power spectra and complexity results and a rank-based approach combining ordinary least squares regression with randomization inference for effective connectivity. ResultsWe observed predominantly null findings. No significant between-group differences emerged for oscillatory power. Complexity comparison yielded results contrary to our hypothesis: psychedelic users exhibited lower complexity values in the eyes-open condition. Effective connectivity revealed no within- or between-network differences that would survive statistical corrections. Additionally, we report a few small-magnitude effects uncovered by exploratory analyses. Conclusions Long-term naturalistic psychedelic users showed largely non-significant differences in oscillatory power, complexity, and network connectivity compared to non-users -- across several measures commonly reported as altered in acute administration studies. These findings raise the question of whether psychedelics neurophysiological signatures persist during abstinence despite repeated prior use, or whether they reflect homeostatic receptor adaptation, individual variability, or contextual factors. Null, incongruous, or subtle effects contribute to the existing evidence base, yet underscore the need for replication in larger, more ecologically valid populations to advance the emerging field of psychedelic neuroscience.

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Incidence of antidepressant withdrawal reactions: A prospective longitudinal cohort study in primary care patients

Rennwald, A.; Horowitz, M. A.; Senn, O.; Neuner-Jehle, O.; Hengartner, M. P.

2026-05-15 psychiatry and clinical psychology 10.64898/2026.05.12.26352975 medRxiv
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Background: The incidence of antidepressant withdrawal reactions in longer-term users and the influence of dosage is insufficiently understood. Objectives: Informed by neuropharmacological models and user surveys, this study examined symptom change during tapering and if increases were specifically associated with reductions below 75% of the minimum effective dose. Design: This was a prospective longitudinal cohort study with seven assessments over six months. Methods: Altogether 32 Swiss adult primary care patients who were on antidepressants for at least six months and in stable remission were assessed at baseline (week 0) before they started tapering and after 2, 4, 6, 8, 16, and 26 weeks. Withdrawal symptoms were measured repeatedly using an adapted version of the Discontinuation-Emergent Signs and Symptoms Scale (DESS) and the main outcome was intra-individual symptom change during intervals. Antidepressant dose was standardized relative to the minimum effective dose in the treatment of depressive and anxiety disorders. Results: Across intervals, reductions below 75% of the minimum effective dose were associated with symptom increases, while reductions above that threshold or no reductions were associated with symptom decreases. After adjusting for potential confounders, the rate of clinically relevant symptom increases contingent on dose reductions below 75% of the minimum effective dose was 33%, as compared to 13% during intervals with no dose reductions (OR=3.2, 1.4 to 7.4). We thus estimated that 60% of the risk of clinically relevant symptom increases was attributable to pharmacological withdrawal effects. The adjusted incidence rates for clinically relevant and severe withdrawal reactions were 32% and 11%, respectively. Conclusions: Consistent with neuropharmacological research findings, we found that antidepressant withdrawal symptoms emerge mostly following reductions below 75% of the minimum effective dose, affecting about one-third of patients. Even small reductions may trigger clinically relevant withdrawal reactions in this lowest dose-range, stressing the need for personalized tapering plans.

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A spoonful of what helps the medicine go down? Improving the reliability of voluntary ingestion for oral dosing in rats and mice

Bartlett, J.; Robinson, E.

2026-03-06 pharmacology and toxicology 10.64898/2026.03.04.709533 medRxiv
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Voluntary ingestion is a refined method for substance administration that can replace oral gavage in rats and mice. It requires no physical restraint and has no associated risks of adverse effects, resulting in improved welfare and reduced distress for both animals and research staff. This method has been shown to be effective for a variety of compounds but is still not widely used due to concerns about accuracy and reliability. One potential issue is aversion to the taste of the compound being administered, including a common issue of bitter taste. In this study we tested compounds used in oral preparations for human medicines to mask bitter tasting drugs, including a commercial formulation designed for this purpose, Bitter Drug Powder (BDP). The masking agents were given in combination with a palatable vehicle (10% condensed milk) and the amount consumed and time to consume recorded. Animals were first habituated to the vehicle with reliable ingestion achieved within a few days. In the first studies, only BDP was fully effective at masking the bitter taste of quinine and preventing the progressive reduction in reliability of intake of the antidepressant, venlafaxine in mice and rats. We were able to replicate these effects using a combination of two different artificial sweeteners, saccharine and acesulfame K, and a thickening agent xanthan gum. These studies demonstrate that using a masking agent can improve the reliability of voluntary oral dosing in mice and rats and provide evidence to support a formulation which is readily available for researchers.

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Unexpected antidepressant-like effects of temozolomide in a mixed sex-cohort of adult rats: role of hippocampal FADD protein

Galvez-Melero, L.; Garcia-Fuster, M. J.

2026-04-27 pharmacology and toxicology 10.64898/2026.04.23.720315 medRxiv
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Temozolomide is the gold standard chemotherapeutic agent used in the treatment of glioblastoma multiforme. Yet its pharmacological use has been linked to the emergence of depressive- and/or anxiety-like behaviors, probably through the inhibition of hippocampal neurogenesis. Since prior studies reporting these negative effects were based on prolonged treatment paradigms (i.e., from 2 weeks to up to 6 months), and given the few reports that have included female rodents in their studies, our approach aimed at further characterizing the behavioral effects induced by temozolomide (25 mg/kg, 1 or 2 cycles, 5 days/cycle) in a mixed-sex cohort of adult rats. To do so, rats were scored across time through specific behavioral tests that capture diverse manifestations of affective-like responses (forced-swim, open field, novelty-suppressed feeding and sucrose preference) or cognitive performance (Barnes maze). At the neurochemical level, we ascertained the effects of 2 cycles of temozolomide on hippocampal neurogenesis (neural progenitors with NeuroD) and other potential neuroplasticity targets (i.e., FADD, BDNF). The main results showed that temozolomide induced unexpected antidepressant-like responses in a treatment-duration manner while decreased hippocampal FADD, a neuroplastic marker previously associated with the acute and repeated actions of most antidepressants. These results break the prior dogma linking increased hippocampal neurogenesis with antidepressant-like efficacy, and suggest that other mechanisms of action, such as the one described through the neuroplastic molecule FADD, might be responsible for the antidepressant-like actions of temozolomide, even in the presence of impaired neurogenesis. Our results, in conjunction with the prior data, suggested cycle- and/or length-dependent treatment effects in terms of temozolomides antidepressant- vs. depressant-like profile, while proposing a novel biomarker of its treatment response.

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Mediators of Treatment Response in Clinical Trial of Naltrexone and Bupropion for Methamphetamine Use Disorder: A Longitudinal Mediation Analysis

Mojtabai, R.; Susukida, R.; Farokhnia, M.; Nguyen, T. Q.; Leggio, L.; Bergeria, C.; Prasad, S.; Dunn, K.; Amin-Esmaeili, M.

2026-05-13 psychiatry and clinical psychology 10.64898/2026.05.09.26352807 medRxiv
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BackgroundThe mechanisms underlying pharmacological treatments for stimulant use disorders are poorly understood. This study examined whether changes in craving, depressive symptoms, and/or impulsivity mediate treatment effect in pharmacotherapy with combined naltrexone and bupropion for methamphetamine use disorder. MethodsThe study was based on secondary analysis of data from the Accelerated Development of Additive Pharmacotherapy Treatment for methamphetamine disorder (ADAPT-2) trial which randomized adults with methamphetamine use disorder to combined treatment with injectable naltrexone (380 mg every three weeks) plus oral bupropion (450 mg daily) versus placebo. A total of 403 adults with methamphetamine use disorder participated in the first Stage; 225 of first Stage participants in the placebo arm who did not respond to treatment were re-randomized in the second Stage. Mediation effects were examined using longitudinal multi-level structural equation modeling. ResultsNaltrexone-bupropion treatment was associated with decreases in drug use, craving, depressive symptoms, and impulsivity. The indirect effect of treatment through change in craving was significant (self-reported use=-0.21, 95% Credible Interval [CrI]=-0.35, -0.09; drug screen-ascertained use=-0.36, 95% CrI=-0.63, -0.16). Change in craving mediated 56% of the treatment effect on self-reported use and 45% of the effect on drug screen-ascertained use. Estimates for mediated effects for depressive symptoms and impulsivity were smaller in magnitude and non-significant. ConclusionReduction in craving mediates the effect of naltrexone-bupropion pharmacotherapy in methamphetamine use disorder. Craving may serve as a surrogate measure of treatment efficacy in short-term trials and help identify promising candidate medications to be tested in larger and longer-term trials. Trial RegistrationClinicalTrials.gov number: NCT03078075.

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Antidepressant Effects of Lauric Acid in a Corticosterone-Induced Murine Model of Depression: Behavioral and Neurochemical Insights

de Paulo, M. C.; Barbosa Moraes, L. R.; Vasconcelos Aguiar, L. M.; de Vasconcelos Melo, C. T.; Magalhaes, J.; Cunha, N. F.

2026-05-19 neuroscience 10.64898/2026.05.15.725442 medRxiv
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BackgroundLauric acid (LA) is a medium-chain saturated fatty acid found in several foods, including vegetable oils and seeds. Previous studies have demonstrated that LA exhibits neuroprotective, antioxidant, and anti-inflammatory properties in experimental models of neuropsychiatric disorders. Therefore, the present study aimed to investigate the behavioral and neurochemical effects of LA in a corticosterone-induced murine model of depression. MethodsMale Swiss mice received corticosterone (CORT; 20 mg/kg, subcutaneously) for 23 consecutive days, while the control group received vehicle only. During the last nine days of the experimental protocol, the animals received the respective treatments by oral gavage: LA (10 or 20 mg/kg), fluvoxamine (FLUV; 50 mg/kg), or vehicle, administered 1 hour after CORT injection. One hour after treatment administration, the animals were subjected to the behavioral tests: Forced Swimming Test (FST), Tail Suspension Test (TST), and Open Field Test (OFT). At the end of the experimental protocol, the animals were euthanized, and the prefrontal cortex (PFC), hippocampus (HPC), and striatum (STR) were collected for neurochemical analyses. ResultsChronic CORT treatment significantly increased immobility time in the FST and TST, characterizing depressive-like behavior. Treatment with LA reversed these behavioral alterations, showing an effect similar to that observed in the FLUV-treated group. In the OFT, LA did not promote significant changes in locomotor activity, suggesting the absence of psychostimulant effects. Regarding neurochemical analyses, LA treatment did not reduce malondialdehyde (MDA) or nitrite/nitrate (NO2-/NO3-) levels, nor did it alter reduced glutathione (GSH) levels in the evaluated brain regions. ConclusionThe results demonstrated that LA treatment was able to reverse corticosterone-induced behavioral alterations in mice, indicating a potential antidepressant-like effect. Furthermore, the observed effects were not associated with nonspecific locomotor alterations. Although LA did not promote significant changes in the evaluated neurochemical markers, these findings reinforce its potential as a therapeutic agent for depressive disorders and highlight the need for further studies to elucidate its mechanisms of action and possible clinical applicability.

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Electroconvulsive seizures for alcohol use disorder: a preclinical study

Garcia-Cabrerizo, R.; Bergas-Cladera, P.; Colom-Rocha, C.; Garcia-Fuster, M. J.

2026-04-01 pharmacology and toxicology 10.64898/2026.03.30.715248 medRxiv
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The use of neuromodulation techniques for the treatment of alcohol use disorder is receiving increasing attention, especially non-invasive approaches, such as repetitive transcranial magnetic stimulation or transcranial direct current stimulation, while the hypothetical use of electroconvulsive therapy remains unexplored. Given our experience inducing electroconvulsive seizures (ECS) for therapeutic purposes in psychopathology rodent models, we evaluated the role of ECS on reducing the increased voluntary ethanol consumption caused by adolescent ethanol exposure in our validated preclinical model. Rats were treated in adolescence with a binge paradigm of ethanol (2 g/kg, i.p.; 3 rounds of 2 days at 48-h intervals; post-natal day, PND 29-30, PND 33-34 and PND 37-38) or saline. Following persistent withdrawal until adulthood, rats were allowed to: voluntarily drink ethanol (20%) by a two-bottle choice test, for 3 days (PND 80-82); treated with ECS (95 mA for 0.6 s, 100 Hz, pulse width 0.6 ms; ear-clip electrodes) or SHAM for 5 days (PND 86-90); re-exposed to voluntarily ethanol exposure (PND 94-96). Brains were collected on PND 97 to evaluate hippocampal markers of ethanol toxicity and/or treatment response (e.g., NeuroD, NF-L, BDNF and NF-L/BDNF ratio). Our results reproduced the increased voluntary ethanol consumption in adult rats induced by adolescent ethanol exposure and demonstrated that ECS could improve this abuse-prone response. Moreover, we suggested a possible role for BDNF in the beneficial effects induced by ECS, especially reducing the neurotoxic ratio NF-L/BDNF. Overall, we provide preclinical evidence for the potential use of ECS as an efficacious treatment for alcohol use disorder.

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Changes in perineuronal net and parvalbumin expression in the orbitofrontal cortex of male Wistar rats following repeated fentanyl administration

Dejeux, M. I. H.; Jewanee, S. S.; Moutos, S.; Trehan, A.; Golbarani, M.; Kwak, J.; Farach, E.; Cheng, N.; Kasaram, S. V.; Ogden, A.; Schwartz, B. A.; Nguyen, J. D.

2026-03-30 neuroscience 10.64898/2026.03.26.714490 medRxiv
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The misuse of opioid medications is a significant health issue in the United States. Very few studies have investigated the effect of opioids on perineuronal nets (PNNs), scaffold-like structures that surround neurons and are involved in the regulation of plasticity-dependent mechanisms such as development, learning and memory, and acquisition of addiction-like phenotypes. Regulation of PNNs in the orbitofrontal cortex (OFC) during periods of drug intoxication or withdrawal is widely unknown. In this study, male Wistar rats were injected with fentanyl (0.125 mg/kg, s.c.) or 0.9% saline twice daily for 7 days and once on day 8 (7continuous days following by 3 days of abstinence) or twice daily for 15 days (5 continuous days followed by 2 days of abstinence for more than 3 weeks) and twice on day 16. Antinociception was evaluated using the tail immersion test immediately before and 30 minutes after injections. Whole-brain coronal slices were collected, and immunohistochemistry was used to identify Wisteria Floribunda Agglutinin (WFA)-positive PNNs and parvalbumin (PV)-expressing cells. Results confirmed that repeated fentanyl injections induced tolerance to the antinociceptive effects, which normalized following acute abstinence periods. WFA intensity decreased following 8 days of injections. Analyses confirmed significant correlations between PV+ density and tail withdrawal latency following 8 days of fentanyl injections. These data confirm that repeated fentanyl injections modulate both WFA+ and PV+ expression in the rodent brain and antinociceptive tolerance in a duration-dependent manner. Overall, these data suggest that perineuronal nets may mediate opioid-induced behavioral effects, such as antinociceptive tolerance, following repeated administration and abstinence in rats.

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A living systematic review, meta-analysis, and open data resource of trials of MDMA-assisted therapy for PTSD

Sevchik, B. L.; Singleton, S. P.; Lahey, A.; Cuijpers, P.; Harrer, M.; Jones, M. T.; Nayak, S. M.; Strain, E. C.; Vandekar, S. N.; Yaden, D. B.; Dworkin, R. H.; Scott, J. C.; Satterthwaite, T. D.

2026-03-30 psychiatry and clinical psychology 10.64898/2026.03.27.26349536 medRxiv
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3,4-methylenedioxymethamphetamine (MDMA) has emerged as a potential treatment for post-traumatic stress disorder (PTSD), generating considerable enthusiasm in the field. However, rapidly changing evidence in a fast-moving field can be challenging to integrate. Here, we present a living systematic review and open-data meta-analytic resource on MDMA treatment for PTSD. In this initial release, six randomized controlled trials comprising 286 participants are included in the database. Our primary model uses inverse-variance random-effects meta-analysis of standardized mean differences on primary outcomes of PTSD. Compared to control conditions, MDMA showed a greater reduction in PTSD symptoms (Hedges' g = -0.71). Meta-regression on both the number of dosing sessions and cumulative dose showed that a higher number of dosing sessions and a higher cumulative dose was related to larger effects of MDMA. Treatment with MDMA as compared to placebo also resulted in higher response (risk ratio (RR) = 1.35) and remission (RR = 2.25) rates. Most studies included in the database had a low risk of bias according to Cochrane guidelines, though these fail to capture pertinent challenges in the field such as expectancy, functional unblinding, potential issues with study conduct, and safety. The current findings were assigned an overall low certainty rating using the GRADE approach. Together, this systematic review and meta-analysis suggests that MDMA-assisted therapy results in short-term decreases in PTSD symptoms across studies to date, though more trials are needed. This living systematic review, meta-analysis, database, and online dashboard (sypres.io) will continue to be updated as evidence emerges, providing a valuable, open, and transparent resource for researchers in a rapidly evolving field.

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Glucagon-like peptide-1 receptor agonist, semaglutide, attenuates intravenous self-administration of fentanyl in female rats

Rojas, K. E.; Gee, S. C.; Wernette, C. L.; Wang, E. X.; Nguyen, E. T.; Nguyen, J. D.

2026-05-21 pharmacology and toxicology 10.64898/2026.05.19.726324 medRxiv
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Current treatments for opioid use disorder (OUD) have major barriers to access. As such, researching new potential therapies for OUD is important to public health. Previous research has implicated glucagon-like peptide-1 (GLP-1) receptor agonists in decreasing the use of addictive substances by animals. In this study, female Wistar rats (N=32) were surgically implanted with jugular catheters and trained to self-administer fentanyl at a fixed-ratio 1 (FR1) schedule of reinforcement for 21 sessions under short- (ShA; 1 hour) or long-access (LgA; 8 hours) conditions. Next, the animals received injections of semaglutide (0.1 mg/kg, s.c.) or saline (0.9% NaCl, s.c.) prior to another FR1 session. The animals underwent a progressive ratio (PR) schedule of reinforcement while receiving saline (i.v.) or fentanyl (0.625-10 {micro}g/kg/inf, i.v.) and semaglutide (0.1 mg/kg, s.c.) or saline (s.c.). Next, the animals underwent a semaglutide (0-0.1 mg/kg, s.c.) dose response procedure at FR1 and a single dose of fentanyl (2.5 {micro}g/kg/inf, i.v.). Following drug discontinuation, spontaneous locomotor activity and withdrawal-like symptoms were measured. Semaglutide dose-dependently decreased fentanyl rewards under ShA and LgA conditions (p<0.05). Under a PR, semaglutide significantly decreased breakpoint (p<0.05), suggesting semaglutide decreases motivation to self-administer fentanyl. Semaglutide-treated ShA animals displayed significantly less withdrawal-like behavior (p<0.05) but not LgA animals. Overall, these findings suggest semaglutide may modulate motivation to seek opioid reward and could be useful in the development of pharmacotherapies to address OUD.

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Effects of NMDA antagonists on social behaviour: a systematic review and meta-analysis of preclinical studies

Gallas-Lopes, M.; Abreu, M. B.; Andrades, M.; Arbo, B. D.; Bastos, L. M.; Caetano, T. C.; Muller, D. V.; Patelli-Alves, A.; Rosa, D. A.; Stein, D. J.; Herrmann, A. P.

2026-05-15 pharmacology and toxicology 10.64898/2026.05.13.724847 medRxiv
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Social withdrawal is a key component of the negative symptom domain of schizophrenia, and pharmacological blockade of the N-methyl-D-aspartate receptor (NMDAR) is widely used to model schizophrenia-relevant phenotypes in animals. However, findings on social behaviour are inconsistent across paradigms and laboratories. We therefore conducted a systematic review and meta-analysis to synthesise the effects of dizocilpine, ketamine, and phencyclidine on social interaction and social preference, to evaluate whether clinically approved antipsychotics modify these outcomes, and to examine locomotor activity measured within the same social tests to aid interpretation. We searched Embase, PubMed and Web of Science without language or date restrictions. Controlled in vivo studies in laboratory animals administering an eligible NMDAR antagonist and reporting social interaction and/or social preference outcomes were included. Two reviewers independently screened records, extracted data and assessed risk of bias. Effect sizes were computed as standardised mean differences and synthesised using correlated multilevel random-effects models with cluster-robust variance estimation. In total, 264 studies met the inclusion criteria. Overall, NMDAR antagonists were associated with reduced social interaction and reduced social preference relative to controls, although the social preference literature appeared vulnerable to small-study effects and imprecision. Locomotor activity measured during social interaction tests tended to be higher following NMDAR antagonists, whereas during social preference no consistent overall change was observed. In animals exposed to NMDAR antagonists, antipsychotics increased social behaviour, but these changes commonly co-occurred with reduced locomotion during social interaction tests, suggesting that improvements in social measures may partly reflect altered behavioural competition and time allocation rather than selective restoration of social functioning. Taken together, the evidence supports an overall link between NMDAR antagonism and reduced social behaviour, but the strength and interpretability of this signal depend on the paradigm and are constrained by heterogeneity and limitations in reporting.

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Modulation of Automatic Alcohol Approach Tendencies using Single-Session 10 Hz rTMS over the Right dLPFC

Verma, A. K.; Kumar, A. D.; Chivukula, U.; Kumar, N.

2026-04-13 neuroscience 10.64898/2026.04.09.717508 medRxiv
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BackgroundMaladaptive drinking is often sustained by automatic approach tendencies toward alcohol cues that override conscious self-control. While cognitive and behavioral modification techniques show some promise, their effects remain limited, highlighting the need for alternative neuromodulatory strategies. The current study examined the feasibility of a single session of 10 Hz repetitive transcranial magnetic stimulation (rTMS) to the right dorsolateral prefrontal cortex (dLPFC) as a targeted approach to reduce automatic alcohol approach tendencies. MethodForty-five healthy alcohol-using participants completed an alcohol approach- avoidance task (A-AAT) with concurrent electroencephalographic recording before and after active or sham stimulation. Primary analyses focused on participants with baseline alcohol approach tendencies (n = 35). ResultsAt baseline, individuals with approach tendencies exhibited attenuated N2 and P3b amplitudes to alcohol relative to non-alcohol cues, indicating reduced cognitive control and attentional mechanisms irrespective of group. Following stimulation, active rTMS selectively facilitated alcohol avoidance responses and enhanced prefrontal N2 amplitudes, suggesting strengthened top-down control and protection against repetition-induced automaticity, which was evident in the sham group. ConclusionThese findings suggest that high-frequency rTMS over the right dLPFC can modulate automatic alcohol-related action tendencies by strengthening neural control mechanisms, supporting its further evaluation as a neuromodulatory adjunct for maladaptive drinking. Baseline motivational profiles may additionally influence rTMS response and warrant consideration when tailoring such approaches.

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Multimodal autonomic arousal tracks dose-dependent affective dynamics during the acute effects of DMT

D'Amelio, T. A.; Gil Garbagnoli, T.; Rodriguez Cuello, J.; Lewis-Healey, E.; Pallavicini, C.; Cavanna, F.; Bruno, N.; de la Fuente, L. A.; Muller, S. A.; Copa, D.; Bekinschtein, T.; Vidaurre Henche, D.; Tagliazucchi, E.

2026-05-04 neuroscience 10.64898/2026.04.30.721872 medRxiv
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Serotonergic psychedelics induce altered states of consciousness characterised by profound changes in emotional experience. Although psychedelics modulate autonomic arousal, sympathetic engagement during their affective effects remains poorly characterised. We recorded cardiac, electrodermal, and respiratory activity in 19 participants following inhalation of 20 or 40 mg of freebase N,N-dimethyltryptamine (DMT) under a semi-naturalistic blinded design, alongside time-resolved retrospective phenomenological reports. DMT induced robust increases across all autonomic markers, integrated into a multimodal index that selectively tracked subjective emotional intensity. Dose-dependent divergence followed modality-specific profiles: heart rate and respiratory differences emerged within the first 2 min post-inhalation, whereas electrodermal activity diverged only during the later phase, with higher doses showing prolonged autonomic engagement. DMT thus produces a transient sympathetic activation co-varying with emotional arousal, followed by gradual disengagement accompanied by pleasantness and bliss. By combining time- and cost-effective peripheral physiological measures with time-resolved phenomenological reports, this work contributes to the objective characterisation of psychedelic-induced affective states and provides a methodological basis for future biomarker research in clinical applications.

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Transcutaneous vagus nerve stimulation enhances reward-effort efficiency in major depressive disorder

Forbes, P. A. G.; Brandt, E.; Aichholzer, M.; Uckermark, C.; Bouzouina, A.; Jacobsen, L.; Repple, J.; Kingslake, J.; Reif-Leonhard, C.; Reif, A.; Schiweck, C.; Thanarajah, S. E.

2026-04-17 psychiatry and clinical psychology 10.64898/2026.04.16.26351003 medRxiv
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Major depressive disorder (MDD) is a highly prevalent psychiatric disorder with changes in motivation to work for rewards being a core symptom. Transcutaneous vagus nerve stimulation (tVNS) has emerged as a promising therapy but its effects on the core features of MDD, such as changes in motivation, remained relatively unexplored. In this randomised, single-blind, cross-over, controlled trial, we used a grip strength effort task to investigate how tVNS impacted choices to exert different levels of physical effort for varying monetary rewards in MDD patients (n=53) and a non-depressed control group (n=45). Compared to sham stimulation, tVNS enhanced the efficiency with which participants with severe depressive symptoms allocated physical effort for rewards (reward-effort efficiency). These effects were not seen in participants with less severe symptoms. Specifically, we found that the effect of tVNS on reward-effort efficiency was driven by reduced unnecessary effort, i.e., a reduction in choices to exert additional effort when this was not required to gain a larger reward. These findings suggest a potential motivational mechanism by which tVNS exerts its therapeutic effects in MDD. Determining whether the effects of tVNS are linked to broader changes in executive functioning, such as improvements in cognitive flexibility in MDD, should be a key aim for future work.

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Imaging FDG PET/CT Study of Nicotinic Acetylcholinergic Receptor α2 Knock-Out Mice and α2 Hypersensitive Mice Compared to Control Mice: Male-Female Differences and Nicotine Effects

Liang, C.; Tucker, T. E.; Coronel, A. D. L.; Nguyen, E. H. N.; Nguyen, J. L.; Intskirveli, I. L.; Lazar, R. L.; Metherate, R. L.; Mukherjee, J.

2026-03-27 neuroscience 10.64898/2026.03.23.713331 medRxiv
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ObjectiveNicotinic acetylcholinergic receptors (nAChRs), comprising of and {beta} subunits are present in the brain and whole body. The less abundant 2-subunit is a fast-acting receptor subtype and plays an important role in cognition and learning. To understand cellular functional consequences, this study evaluated glucose metabolism using [18F]FDG PET/CT in 2 knockout (2KO) and 2 hypersensitive (2HS) mice. MethodsControl (CN; 4M, 4F), 2 knockout (2KO; 4M, 4F) and 2 hypersensitive (2HS; 4M,4F), 12-16 month old mice were used. Mice were fasted and injected with [18F]FDG (3-5 MBq) while awake. After 40 minutes they underwent whole body PET/CT. On a separate day, nicotine challenge [18F]FDG studies were done. Reconstructed images were analyzed to obtain standard uptake values (SUV) of [18F]FDG in brain and interscapular brown adipose tissue (IBAT). Statistical analysis was performed. ResultsThe 2HS male mice exhibited the largest brain increase in [18F]FDG compared to 2KO male mice. The rank order of brain [18F]FDG uptake in the 3 groups: 2HS[male]> CN[male]> 2KO[male]> CN[female]= 2KO[female][&ge;] 2HS[female]. Nicotine treatment reduced brain [18F]FDG uptake in all mice. Females had lower [18F]FDG uptake compared to males and were less sensitive to 2 nAChR. In the case of IBAT, 2KO mice had significantly higher baseline [18F]FDG uptake compared to the other two groups: 2KO[male]> 2KO[female]> 2HS[female]> 2HS[male]> CN[female]> CN[male]. Nicotine decreased IBAT in 2KO mice rather than increase as observed in CN and 2HS mice. Conclusions2 nAChRs plays a significant role in brain activation as exhibited by the increase in [18F]FDG in 2HS mice. In the absence of regulatory control by the 2 nAChR, the 2KO mice IBAT exhibited higher [18F]FDG IBAT compared to controls and 2HS mice. Female mice were less affected by nicotine compared to the male mice. Overall, 2 nAChRs played a significant role in glucose metabolism in the brain and IBAT.

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MDMA-Assisted Therapy Randomized Controlled Trial Incremental Effects Systematic Review and Meta-Analysis

Borgogna, N. C.; Whittington, D. D.; Owen, T.; Petrovitch, D.; Vaughn, J.; Struble, C.; Pagano, L. A.; Aita, S. L.; Hill, B. D.

2026-05-20 psychiatry and clinical psychology 10.64898/2026.05.05.26352468 medRxiv
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Mental illness poses a substantial global burden, yet existing psychotherapies and psychopharmacologies often produce limited outcomes. Psychedelic assisted therapies have emerged as potential transdiagnostic interventions. In particular, 3,4 methylenedioxymethamphetamine assisted therapy (MDMA AT) has generated interest for its rapid psychological effects and potential to enhance psychotherapy outcomes. However, the incremental efficacy of MDMA AT relative to control interventions across transdiagnostic outcomes remains unclear. Further, there have been emerging concerns regarding harm reporting quality in MDMA AT clinical trials. We conducted a systematic review and meta analysis of MDMA AT randomized controlled trials. Eleven publications representing eight controlled trials with 10 analyzed subgroups (n = 295 participants) were included in meta-analyses. Two additional secondary publications were included for harm reporting syntheses (k = 13 total). Across 114 extracted effect sizes, MDMA AT demonstrated a significant moderate-to-large incremental reduction in psychopathology relative to controls (g = 1.03, 95% CI [0.46, 1.60]), though heterogeneity was high (I squared = 76%). Incremental effects were larger versus inert placebos (g = 1.27) than active controls (g = 0.75). Symptom specific analyses indicated strong incremental effects for trauma reduction (g=1.46 [95% CI: 0.67, 2.25]) and smaller non-significant effects for depression (g=0.51 [95% CI: -0.06, 1.08]). Harm reporting quality synthesis showed only 23% of publications met high-quality reporting standards. Overall, MDMA AT demonstrates potential transdiagnostic efficacy, but small samples, confounding factors, and mediocre harm reporting highlight the need for larger more transparent clinical trials.

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Exploring the Antidepressant Effects of Saffron Constituents: Targeting Dopamine and Serotonin Transport Proteins, and Monoamine Oxidase-B: An in Silico Evidence-Based Study

SINGH, B.; sharma, D.; Madhavrao Shingatgeri, V.; Lomash, V.

2026-03-19 neuroscience 10.64898/2026.03.16.712249 medRxiv
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Globally, about 264 million individuals across all age groups are impacted by depression, a prevalent central nervous system (CNS) condition. Chronic and enduring depression might result in significant health consequences. Numerous pharmaceutical antidepressants exist for the management of mild to severe depression, largely functioning by modifying neurotransmitter levels in the brain. Nevertheless, these drugs frequently induce a variety of side effects, such as insomnia, constipation, exhaustion, drowsiness, and anxiety. Saffron (Crocus sativus L.) is widely acknowledged as a natural antidepressant with little adverse effects. This study investigated the potential antidepressant mechanisms of saffrons principal bioactive compounds safranal, crocin, and picrocrocin via molecular docking against critical target proteins associated with depression, namely the dopamine transporter (DAT), serotonin transporter (SERT), and monoamine oxidase B (MAO-B). Molecular docking was conducted with AutoDock 4.2 to assess the binding affinity and interaction energy of these drugs with the target proteins. Furthermore, Discovery Studio facilitated the viewing and study of both interacting and non-interacting residues at the docking sites, juxtaposing these interactions with those of established inhibitors in crystal structures. The permeability of the blood-brain barrier (BBB), pharmacokinetic characteristics, and toxicity profiles of saffron components were evaluated using SWISS ADME, DataWarrior, and Osiris Molecular Property Explorer. Among the evaluated elements, safranal had the greatest potential as a competitive inhibitor of the dopamine transporter, according to its notable blood-brain barrier permeability, robust binding affinity, and analogous interaction residues in comparison to nortriptyline, a recognized inhibitor. Our findings indicate that safranal may be a viable natural alternative to traditional antidepressants, with minimized adverse effects.