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Olivier Taymans

Increased sensitivity to strong perturbations in a whole-brain model of LSD


Lysergic acid diethylamide (LSD) is a potent psychedelic drug, which has seen a revival in clinical and pharmacological research within recent years. Human neuroimaging studies have shown fundamental changes in brain-wide functional connectivity and an expansion of dynamical brain states, thus raising the question about a mechanistic explanation of the dynamics underlying these alterations. Here, we applied a novel perturbational approach based on a whole-brain computational model, which opens up the possibility to externally perturb different brain regions in silico and investigate differences in dynamical stability of different brain states, i.e. the dynamical response of a certain brain region to an external perturbation. After adjusting the whole-brain model parameters to reflect the dynamics of functional magnetic resonance imaging (fMRI) BOLD signals recorded under the influence of LSD or placebo, perturbations of different brain areas were simulated by either promoting or disrupting synchronization in the regarding brain region. After perturbation offset, we quantified the recovery characteristics of the brain area to its basal dynamical state with the Perturbational Integration Latency Index (PILI) and used this measure to distinguish between the two brain states. We found significant changes in dynamical complexity with consistently higher PILI values after LSD intake on a global level, which indicates a shift of the brain’s global working point further away from a stable equilibrium as compared to normal conditions. On a local level, we found that the largest differences were measured within the limbic network, the visual network and the default mode network. Additionally, we found a higher variability of PILI values across different brain regions after LSD intake, indicating higher response diversity under LSD after an external perturbation. Our results provide important new insights into the brain-wide dynamical changes underlying the psychedelic state – here provoked by LSD intake – and underline possible future clinical applications of psychedelic drugs in particular psychiatric disorders.

Jobst, B. M., Atasoy, S., Ponce-Alvarez, A., Sanjuán, A., Roseman, L., Kaelen, M., Carhart-Harris, R., Kringelbach, M. L., & Deco, G. (2021). Increased sensitivity to strong perturbations in a whole-brain model of LSD. NeuroImage, 230, 117809.

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The impact of 3,4-methylendioxymetamphetamine (MDMA) abstinence on seeking behavior and the expression of the D 2-like and mGlu 5 receptors in the rat brain using saturation binding analyses


The abundance of research indicates that enriched environment acts as a beneficial factor reducing the risks of relapse in substance use disorder. There is also strong evidence showing the engagement of brain dopaminergic and glutamatergic signaling through the dopamine D2-like and metabotropic glutamate type 5 (mGlu5) receptors, respectively, that has a direct impact on drug reward and drug abstinence. The present study involved 3,4-methylendioxymethamphetamine (MDMA) self-administration with the yoked-triad procedure in rats kept under different housing conditions during abstinence – enriched environment (EE) or isolation cage (IC) conditions – aimed at evaluating changes in brain receptors affecting drug-seeking behavior as well as density and affinity of the D2-like and mGlu5 receptors in several regions of the animal brain. Our results show that exposure to EE conditions strongly reduced active lever presses during cue-induced drug-seeking. At the neurochemical level, we demonstrated marked decreases of D2-like receptor affinity in the dorsal striatum in rats previously self-administering MDMA under EE and increases in density under IC conditions. Moreover, we found the increases in the density and decreases in the affinity of the D2-like receptor in the prefrontal cortex and nucleus accumbens provoked by IC conditions. The mGlu5 receptor density decreased only in the prefrontal cortex after IC and EE abstinence. Moreover, our study has revealed a clear decrease in mGlu5 receptor density in the nucleus accumbens in the group actively administering MDMA only under EE conditions. This study demonstrates that housing conditions have impact on drug-seeking behavior in rats during abstinence from MDMA self-administration. The observed changes in the dopamine D2-like and mGlu5 receptor Bmax and/or Kd values were brain-region specific and related to either pharmacological and/or motivational features of MDMA.

Frankowska, M., Miszkiel, J., Pomierny-Chamiolo, L., Pomierny, B., Celeste Borelli, A., Suder, A., & Filip, M. (2020). The impact of 3,4-methylendioxymetamphetamine (MDMA) abstinence on seeking behavior and the expression of the D2-like and mGlu5 receptors in the rat brain using saturation binding analyses. Journal of physiology and pharmacology : an official journal of the Polish Physiological Society, 71(4), 10.26402/jpp.2020.4.09.

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Efficacy of 3,4-methylenedioxymethamphetamine (MDMA)-assisted psychotherapy for posttraumatic stress disorder: A systematic review and meta-analysis


Background: Posttraumatic stress disorder (PTSD) is a common psychiatric condition that can develop following a traumatic experience. PTSD is associated with significant disability, a large economic burden, and despite the range of therapies to treat PTSD, response to antidepressants is limited. A growing body of clinical research suggests the efficacy of 3,4-methylenedioxymethamphetamine (MDMA)-assisted psychotherapy in individuals with treatment-refractory PTSD.

Aim: To assess the effectiveness and safety of MDMA-assisted psychotherapy for reducing symptoms of PTSD, a systematic review and meta-analysis was undertaken.

Methods: Six online databases were searched from inception to December 2018. Reference lists of relevant articles were manually searched as well as electronic sources of ongoing trials and conference proceedings. Researchers active in the subject were also contacted. Eligible studies included randomized and quasi-randomized clinical trials using MDMA-assisted psychotherapy for PTSD in comparison with other medications, placebo or no medication (supportive care). We used standard methodological procedures expected by the Cochrane Collaboration. Two authors assessed studies for inclusion and extracted data. Using random-effects meta-analysis with Cochrane’s Review Manager 5.3, we obtained standardized mean differences [SMD] and rate ratios [RR] for reduction in PTSD symptomatology.

Results: A total of 5 trials met inclusion criteria, totaling 106 participants (average age: 35-40 years, 70% female). Studies were rated as moderate in quality. MDMA-assisted psychotherapy demonstrated a high rate of clinical response (RR = 3.47, 95% CI: 1.70, 7.06), remission (RR = 2.63, 95% CI: 1.37, 5.02), with a large effect size at reducing the symptoms of PTSD (SMD = 1.30, 95% CI: 0.66, 1.94). Available evidence indicates that MDMA was well-tolerated, with few serious adverse events reported across studies.

Conclusions: MDMA-assisted psychotherapy appears to be a potentially safe, effective, and durable treatment for individuals with chronic, treatment-refractory PTSD. However, future studies involving larger samples and longer durations of treatment and follow-up are warranted-and underway.

Bahji, A., Forsyth, A., Groll, D., & Hawken, E. R. (2020). Efficacy of 3,4-methylenedioxymethamphetamine (MDMA)-assisted psychotherapy for posttraumatic stress disorder: A systematic review and meta-analysis. Progress in neuro-psychopharmacology & biological psychiatry, 96, 109735.

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