OPEN Foundation

Psychology

Therapeutic effects of classic serotonergic psychedelics: A systematic review of modern-era clinical studies

Abstract

Objective: To conduct a systematic review of modern-era (post-millennium) clinical studies assessing the therapeutic effects of serotonergic psychedelics drugs for mental health conditions. Although the main focus was on efficacy and safety, study characteristics, duration of antidepressants effects across studies, and the role of the subjective drug experiences were also reviewed and presented.

Method: A systematic literature search (1 Jan 2000 to 1 May 2020) was conducted in PubMed and PsychINFO for studies of patients undergoing treatment with a serotonergic psychedelic.

Results: Data from 16 papers, representing 10 independent psychedelic-assisted therapy trials (psilocybin = 7, ayahuasca = 2, LSD = 1), were extracted, presented in figures and tables, and narratively synthesized and discussed. Across these studies, a total of 188 patients suffering either cancer- or illness-related anxiety and depression disorders (C/I-RADD), major depressive disorder (MDD), obsessive-compulsive disorder (OCD) or substance use disorder (SUD) were included. The reviewed studies established feasibility and evidence of safety, alongside promising early data of efficacy in the treatment of depression, anxiety, OCD, and tobacco and alcohol use disorders. For a majority of patients, the therapeutic effects appeared to be long-lasting (weeks-months) after only 1 to 3 treatment session(s). All studies were conducted in line with guidelines for the safe conduct of psychedelic therapy, and no severe adverse events were reported.

Conclusion: The resurrection of clinical psychedelic research provides early evidence for treatment efficacy and safety for a range of psychiatric conditions, and constitutes an exciting new treatment avenue in a health area with major unmet needs.

Andersen, K., Carhart-Harris, R., Nutt, D. J., & Erritzoe, D. (2021). Therapeutic effects of classic serotonergic psychedelics: A systematic review of modern-era clinical studies. Acta psychiatrica Scandinavica, 143(2), 101–118. https://doi.org/10.1111/acps.13249

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Psychedelic-assisted therapy for functional neurological disorders: A theoretical framework and review of prior reports

Abstract

Functional neurological disorders (FNDs), which are sometimes also referred to as psychogenic neurological disorders or conversion disorder, are common disabling neuropsychiatric disorders with limited treatment options. FNDs can present with sensory and/or motor symptoms, and, though they may mimic other neurological conditions, they are thought to occur via mechanisms other than those related to identifiable structural neuropathology and, in many cases, appear to be triggered and sustained by recognizable psychological factors. There is intriguing preliminary evidence to support the use of psychedelic-assisted therapy in a growing number of psychiatric illnesses, including FNDs. We review the theoretical arguments for and against exploring psychedelic-assisted therapy as a treatment for FNDs. We also provide an in-depth discussion of prior published cases detailing the use of psychedelics for psychosomatic conditions, analyzing therapeutic outcomes from a contemporary neuroscientific vantage as informed by several recent neuroimaging studies on psychedelics and FNDs.

Stewart, B., Dean, J. G., Koek, A., Chua, J., Wabl, R., Martin, K., Davoodian, N., Becker, C., Himedan, M., Kim, A., Albin, R., Chou, K. L., & Kotagal, V. (2020). Psychedelic-assisted therapy for functional neurological disorders: A theoretical framework and review of prior reports. Pharmacology research & perspectives, 8(6), e00688. https://doi.org/10.1002/prp2.688

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The Psychedelic Personality: Personality Structure and Associations in a Sample of Psychedelics Users

Abstract

Research on the relationship between personality and psychedelics use has found evidence of a two-way influence where the personality structure predicts individual responses to psychedelics, and psychedelics use results in lasting changes to the individual’s personality structure. This study used brief personality measures in the form of the Ten-Item Personality Inventory (TIPI) and a simplified version of the Risk Taking Index (RTI) in order to measure personality traits in a sample of psychedelics users (N = 319). The participants in the study scored consistently higher than norms on each of the Big Five traits except Extraversion, and on every dimension of risk taking in the RTI. In multivariate logistic regression analyses, personality structure was associated with characteristics of the psychedelic experience that included the feelings of fear, love, and peace as well as states of perceived contact with non-ordinary beings and transcendent forces.

Johnstad P. G. (2021). The Psychedelic Personality: Personality Structure and Associations in a Sample of Psychedelics Users. Journal of psychoactive drugs, 53(2), 97–103. https://doi.org/10.1080/02791072.2020.1842569

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Pivotal mental states

Abstract

This paper introduces a new construct, the ‘pivotal mental state’, which is defined as a hyper-plastic state aiding rapid and deep learning that can mediate psychological transformation. We believe this new construct bears relevance to a broad range of psychological and psychiatric phenomena. We argue that pivotal mental states serve an important evolutionary function, that is, to aid psychological transformation when actual or perceived environmental pressures demand this. We cite evidence that chronic stress and neurotic traits are primers for a pivotal mental state, whereas acute stress can be a trigger. Inspired by research with serotonin 2A receptor agonist psychedelics, we highlight how activity at this particular receptor can robustly and reliably induce pivotal mental states, but we argue that the capacity for pivotal mental states is an inherent property of the human brain itself. Moreover, we hypothesize that serotonergic psychedelics hijack a system that has evolved to mediate rapid and deep learning when its need is sensed. We cite a breadth of evidences linking stress via a variety of inducers, with an upregulated serotonin 2A receptor system (e.g. upregulated availability of and/or binding to the receptor) and acute stress with 5-HT release, which we argue can activate this primed system to induce a pivotal mental state. The pivotal mental state model is multi-level, linking a specific molecular gateway (increased serotonin 2A receptor signaling) with the inception of a hyper-plastic brain and mind state, enhanced rate of associative learning and the potential mediation of a psychological transformation.

Brouwer, A., & Carhart-Harris, R. L. (2021). Pivotal mental states. Journal of psychopharmacology (Oxford, England), 35(4), 319–352. https://doi.org/10.1177/0269881120959637

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Prescribing meaning: hedonistic perspectives on the therapeutic use of psychedelic-assisted meaning enhancement

Abstract

The recent renaissance in research on psychedelic-assisted psychotherapy is showing great promise for the treatment of many psychiatric conditions. Interestingly, therapeutic outcomes for patients undergoing these treatments are predicted by the occurrence of a mystical experience-an experience characterised in part by a sense of profound meaning. This has led to hypotheses that psychedelic-assisted psychotherapy is therapeutic because it enhances perception of meaning, and consequently leads to a meaning response (a therapeutic mechanism that has been well described in the philosophical literature on the placebo effect). The putative mechanism of action of psychedelics as meaning enhancers raises normative ethical questions as to whether it can be justified to pharmacologically increase the perception of meaning in order to heal patients. Using the perspectives of hedonistic moral theories, this paper argues that if psychedelics operate as meaning enhancers, psychedelic-assisted psychotherapy can be ethically justified. An anti-hedonistic objection is presented by applying Robert Nozick’s Experience Machine thought experiment to the case of psychedelic-assisted psychotherapy. However, it is argued that this objection falls short for two reasons. First, even if pleasure and pain are not the only consequences which have moral value they are not morally irrelevant, therefore, therapeutic meaning enhancement can still be justified in cases of extreme suffering. Second, it is possible that psychedelic states of consciousness do not represent a false reality, hence their therapeutic meaning enhancement is not problematic according to Nozick’s standards.

Miceli McMillan R. (2021). Prescribing meaning: hedonistic perspectives on the therapeutic use of psychedelic-assisted meaning enhancement. Journal of medical ethics, 47(10), 701–705. https://doi.org/10.1136/medethics-2020-106619

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Post-acute psychological effects of classical serotonergic psychedelics: a systematic review and meta-analysis

Abstract

Background: Scientific interest in the therapeutic effects of classical psychedelics has increased in the past two decades. The psychological effects of these substances outside the period of acute intoxication have not been fully characterized. This study aimed to: (1) quantify the effects of psilocybin, ayahuasca, and lysergic acid diethylamide (LSD) on psychological outcomes in the post-acute period; (2) test moderators of these effects; and (3) evaluate adverse effects and risk of bias.

Methods: We conducted a systematic review and meta-analysis of experimental studies (single-group pre-post or randomized controlled trials) that involved administration of psilocybin, ayahuasca, or LSD to clinical or non-clinical samples and assessed psychological outcomes ⩾24 h post-administration. Effects were summarized by study design, timepoint, and outcome domain.

Results: A total of 34 studies (24 unique samples, n = 549, mean longest follow-up = 55.34 weeks) were included. Classical psychedelics showed significant within-group pre-post and between-group placebo-controlled effects on a range of outcomes including targeted symptoms within psychiatric samples, negative and positive affect-related measures, social outcomes, and existential/spiritual outcomes, with large between-group effect in these domains (Hedges’ gs = 0.84 to 1.08). Moderator tests suggest some effects may be larger in clinical samples. Evidence of effects on big five personality traits and mindfulness was weak. There was no evidence of post-acute adverse effects.

Conclusions: High risk of bias in several domains, heterogeneity across studies, and indications of publication bias for some models highlight the need for careful, large-scale, placebo-controlled randomized trials.

Goldberg, S. B., Shechet, B., Nicholas, C. R., Ng, C. W., Deole, G., Chen, Z., & Raison, C. L. (2020). Post-acute psychological effects of classical serotonergic psychedelics: a systematic review and meta-analysis. Psychological medicine, 50(16), 2655–2666. https://doi.org/10.1017/S003329172000389X

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Effect of Ketamine on Rumination in Treatment-Resistant Depressive Patients

Abstract

Background: A rapid antidepressant effect of ketamine has repeatedly been documented in the literature, and identifying clinical features associated with a better response to this treatment is currently an essential question. Considering the relationship between rumination and depression and the need to identify potential predictors of response to ketamine, we analyzed the effect of a single injection of ketamine 0.5 mg/kg on rumination in treatment-resistant depressive (TRD) patients and explored whether baseline ruminative style and early improvements of rumination would predict a greater antidepressant effect of ketamine.

Methods: Ten TRD outpatients who participated in a 4-week open study on the antidepressant effect of ketamine also completed the Ruminative Response Scale the day before, the day after, and a week after ketamine administration.

Results: We found that in our patients, a single rapid 1-minute intravenous injection of ketamine 0.5 mg/kg was efficacious in reducing rumination, but neither severity of rumination at baseline nor early improvements of rumination after ketamine injection predicted antidepressant response.

Conclusions: Our preliminary data suggest that a single injection of ketamine 0.5 mg/kg can be efficacious in reducing rumination in TRD patients but rumination does not seem to be a useful clinical predictor of response to ketamine. Larger studies are necessary to confirm these results.

Vidal, S., Jermann, F., Aubry, J. M., Richard-Lepouriel, H., & Kosel, M. (2020). Effect of Ketamine on Rumination in Treatment-Resistant Depressive Patients. Journal of clinical psychopharmacology, 40(6), 607–610. https://doi.org/10.1097/JCP.0000000000001305

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Neurocognitive impact of ketamine treatment in major depressive disorder: A review on human and animal studies – PubMed

Abstract

Background: Most recent evidence support a rapid and sustained antidepressant effect of subanesthetic dose of intravenous ketamine in patients with major depressive disorder (MDD). However, clinical and animal studies investigating the effects of intravenous ketamine on specific functional domains disrupted by depression reported conflicting results. Therefore, the aim of this review is to provide an overview of the recent findings exploring the cognitive effects of ketamine in depression.
Methods: After a bibliographic search on PubMed, Medline and PsycInfo, we retrieved 11 original studies meeting our research criteria, 7 in humans with MDD or Treatment Resistant Disorder and 4 using rats models for depression.
Results: Overall the results showed that a) ketamine reduced activation and normalized connectivity measures of several brain regions related to depressive behaviors and reversed deficits in cognitive flexibility and coping response strategy in rats with depressive features, and b) ketamine leads to a no significant impairment on neurocognitive functions in most of the studies, with only three studies observing improvements in speed of processing, verbal learning, sustained attention and response control, verbal and working memory.
Limitations: The methodological heterogeneity, in terms of neuropsychological tests used and cognitive domain explored, of the studies included.
Conclusions: Most of the studies included showed no significant cognitive impairments in MDD patients after ketamine treatment. Furthermore, the results of the fMRI studies considered suggest that ketamine may have a normalizing effect on brain functions during attentional and emotional processing in MDD patients. However, further studies are needed to confirm these preliminary evidences.
Crisanti, C., Enrico, P., Fiorentini, A., Delvecchio, G., & Brambilla, P. (2020). Neurocognitive impact of ketamine treatment in major depressive disorder: A review on human and animal studies. Journal of Affective Disorders., 10.1016/j.jad.2020.07.119
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Rapid and sustained decreases in suicidality following a single dose of ayahuasca among individuals with recurrent major depressive disorder: results from an open-label trial

Abstract

Rationale: Suicidality is a major public health concern with limited treatment options. Accordingly, there is a need for innovative interventions for suicidality. Preliminary evidence indicates that treatment with the psychedelic ayahuasca may lead to decreases in depressive symptoms among individuals with major depressive disorder (MDD). However, there remains limited understanding of whether ayahuasca also leads to reductions in suicidality.

Objective: To examine the acute and post-acute effect of ayahuasca on suicidality among individuals with MDD.

Methods: We conducted a secondary analysis of an open-label trial in which individuals with recurrent MDD received a single dose of ayahuasca (N = 17). Suicidality was assessed at baseline; during the intervention; and 1, 7, 14, and 21 days after the intervention.

Results: Among individuals with suicidality at baseline (n = 15), there were significant acute (i.e., 40, 80, 140, and 180 min after administration) and post-acute (1, 7, 14, and 21 days after administration) decreases in suicidality following administration of ayahuasca. Post-acute effect sizes for decreases in suicidality were large (Hedges’ g = 1.31-1.75), with the largest effect size 21 days after the intervention (g = 1.75).

Conclusions: When administered in the appropriate context, ayahuasca may lead to rapid and sustained reductions in suicidality among individuals with MDD. Randomized, double-blind studies with larger sample sizes are needed to confirm this early finding.

Zeifman, R. J., Singhal, N., Dos Santos, R. G., Sanches, R. F., de Lima Osório, F., Hallak, J., & Weissman, C. R. (2021). Rapid and sustained decreases in suicidality following a single dose of ayahuasca among individuals with recurrent major depressive disorder: results from an open-label trial. Psychopharmacology, 238(2), 453–459. https://doi.org/10.1007/s00213-020-05692-9

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Toxicokinetics and Toxicodynamics of Ayahuasca Alkaloids N, N-Dimethyltryptamine (DMT), Harmine, Harmaline and Tetrahydroharmine: Clinical and Forensic Impact

Abstract

Ayahuasca is a hallucinogenic botanical beverage originally used by indigenous Amazonian tribes in religious ceremonies and therapeutic practices. While ethnobotanical surveys still indicate its spiritual and medicinal uses, consumption of ayahuasca has been progressively related with a recreational purpose, particularly in Western societies. The ayahuasca aqueous concoction is typically prepared from the leaves of the N,N-dimethyltryptamine (DMT)-containing Psychotria viridis, and the stem and bark of Banisteriopsis caapi, the plant source of harmala alkaloids. Herein, the toxicokinetics and toxicodynamics of the psychoactive DMT and harmala alkaloids harmine, harmaline and tetrahydroharmine, are comprehensively covered, particularly emphasizing the psychological, physiological, and toxic effects deriving from their concomitant intake. Potential therapeutic utility, particularly in mental and psychiatric disorders, and forensic aspects of DMT and ayahuasca are also reviewed and discussed. Following administration of ayahuasca, DMT is rapidly absorbed and distributed. Harmala alkaloids act as potent inhibitors of monoamine oxidase A (MAO-A), preventing extensive first-pass degradation of DMT into 3-indole-acetic acid (3-IAA), and enabling sufficient amounts of DMT to reach the brain. DMT has affinity for a variety of serotonergic and non-serotonergic receptors, though its psychotropic effects are mainly related with the activation of serotonin receptors type 2A (5-HT2A). Mildly to rarely severe psychedelic adverse effects are reported for ayahuasca or its alkaloids individually, but abuse does not lead to dependence or tolerance. For a long time, the evidence has pointed to potential psychotherapeutic benefits in the treatment of depression, anxiety, and substance abuse disorders; and although misuse of ayahuasca has been diverting attention away from such clinical potential, research onto its therapeutic effects has now strongly resurged.

Brito-da-Costa, A. M., Dias-da-Silva, D., Gomes, N., Dinis-Oliveira, R. J., & Madureira-Carvalho, Á. (2020). Toxicokinetics and Toxicodynamics of Ayahuasca Alkaloids N,N-Dimethyltryptamine (DMT), Harmine, Harmaline and Tetrahydroharmine: Clinical and Forensic Impact. Pharmaceuticals (Basel, Switzerland), 13(11), 334. https://doi.org/10.3390/ph13110334

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