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Microdosing psychedelics as cognitive and emotional enhancers
Abstract
"Microdosing, " the use of small doses of psychedelics as cognitive, creativity, or productivity enhancers, has become a popular trend. However, scientific investigation of microdoses of psychedelics remains one of the least developed areas of psychedelic research. In this article, we review available studies of microdosing psychedelics in humans and in animal models. We suggest that microdosing may safely facilitate cognitive as well as emotional enhancement. Microdosing may derive some of its purported long-term cognition and creativity enhancing effects from the capacity of psychedelics to induce potentially beneficial persisting brain changes such as enhanced neural plasticity, enhancement of neurogenesis, or reduction of neuroinflammation. Nevertheless, despite promising results, recent findings also highlight that substantial further study and appropriate caution is warranted as researchers attempt to understand the long-term or even lifelong effects of the exposure to microdoses of psychedelic compounds on the brain and the body.
... In a recent study, intermittent low doses of DMT given to rats produced an antidepressant-like phenotype with enhanced fear extinction suggesting that psychedelic microdosing may alleviate symptoms of mood and anxiety disorders in humans (Cameron et al., 2019). One review of both human and animal microdosing trials suggests it may facilitate cognitive as well as emotional enhancement due to beneficial and persisting brain changes, enhancement of neural plasticity and neurogenesis, or reduction of neuroinflammation (Rifkin et al., 2020). ...
... Indeed, Cavanna et al.'s (2022) study found impaired performance on cognitive tasks. Further trials should also investigate the role of dopamine activation, identification of underlying mechanisms of action, the role of gut bacteria in microdosing, as well as the long-term effects of chronic microdosing, especially given the potential cardiac impacts of chromic 5-HT2B agonism, which has been previously associated with heart valve fibrosis (Rifkin et al., 2020). ...
A rapid review synthesizing published research on the possible therapeutic applications of psychedelics.
... Despite the resurgence of interest in LSD and other psychedelics, the full cognitive effects of LSD remain largely unarticulated (Rifkin et al., 2020). This situation will likely hamper the therapeutic deployment of these substances and in the case of LSD, there is a pressing need to evaluate its cognitive effects in the absence of drug-induced changes in conscious experience. ...
... Microdoses of LSD are frequently taken by people who wish to improve their cognitive or emotional wellbeing (Rifkin et al., 2020). This study examined whether very low doses of LSD affect overall working memory recall and whether there is any evidence that LSD exerts differentially effects on ignoring and updating information. ...
The effect of low doses (<=20 μg) of LSD on working memory, in the absence of altered states of consciousness, remain largely unexplored. Given its possible effects on serotonin 5-HT2A receptors and dopaminergic signalling, it could be hypothesised that LSD microdoses modulate working memory recall. Moreover, in line with computational models, LSD microdoses could exert antagonistic effects on distracter resistance and updating. Here, we tested this hypothesis in a randomised double-blind, placebo-controlled study comparing three different LSD microdoses (5 μg, 10μg and 20μg) with placebo. After capsule administration, participants performed a modified delay-match-to-sample (DMTS) dopamine-sensitive task. The standard DMTS task was modified to include novel items in the delay period between encoding and probe. These novel items either had to be ignored or updated into working memory. There was no evidence that LSD microdoses affected the accuracy or efficiency of working memory recall and there was no evidence for differential effects on ignoring or updating. Due to the small sample of participants, these results are preliminary and larger studies are required to establish whether LSD microdoses affect short-term recall.
... kognitivní funkce či emotivitu. 97,[99][100][101] Užívá se několikanásobně nižší dávka, než je dávka potřebná k vyvolání psychedelického stavu (tj. subhalucinogenní dávka). ...
Tato publikace představuje komplexní úvod do problematiky a dosud první souhrnný přehled situace v oblasti fenoménu užívání psychedelik v České republice, shrnující výsledky výzkumného projektu Aplikace výzkumných metod při tvorbě návrhu systému služeb pro uživatele psychedelických látek realizovaného v letech 2019–2021 v Národním ústavu duševního zdraví a spolufinancovaného se státní podporou Technologické agentury České republiky.
This publication is a comprehensive introduction to the phenomenon
and so far the first complex overview of the situation in the field
of psychedelics use in the Czech Republic, summarizing the results
of the research project Application of Research Methods in Creating
a Design of a System of Services for Users of Psychedelics (hereinafter referred to as National Psychedelic Research) implemented
in 2019–2021 at the National Institute of Mental Health.
... For example, the following methods have been experimentally shown to enhance creativity: exercise (Frith & Loprinzi, 2018;Gondola, 1986;Gondola & Tuckman, 1985;Román et al., 2018;Steinberg et al., 1997), meditation and mindfulness (Capurso et al., 2014;Ding et al., 2014;Lippelt et al., 2014;Müller et al., 2016), mind wandering (Baird et al., 2012;Zedelius & Schooler, 2015), cognitive training (Birdi, 2005;Byrge & Tang, 2015;Ritter & Mostert, 2017;Scott et al., 2004), nature exposure (Atchley et al., 2012;Ferraro, 2015;Plambech & Konijnendijk van den Bosch, 2015;Yu & Hsieh, 2020), alcohol (Benedek & Zöhrer, 2020;Benedek et al., 2017), caffeine (Y. Huang et al., 2018;Jiang et al., 2022;Zabelina & Silvia, 2020), pharmacological drugs (Alexander et al., 2007;Beversdorf, 2013Beversdorf, , 2019Beversdorf et al., 1999;McBride et al., 2021), and psychedelic substances (Hartogsohn, 2018;Prochazkova et al., 2018;Rifkin et al., 2020;Sessa, 2008). As researchers continue to explore the efficacy of neuromodulation techniques for enhancing creative cognition, the effects of neuromodulation should be tested against the aforementioned methods. ...
We review several new and emerging methods of non-invasive neuromodulation and consider their potential to enhance creative cognition. This review covers the following techniques: transcranial electric stimulation (tES) (which includes transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial random noise stimulation (tRNS)), transcranial magnetic stimulation (TMS), transcranial focused ultrasound stimulation (tFUS), and neurofeedback training (NFT). For each technique, we explain the basic mechanism of action, review relevant research demonstrating its ability to enhance creative cognition, consider limitations and advantages, and suggest future research directions. Lastly, we offer broader conclusions and recommendations for the field of creativity neuromodulation.
... (Koben, 2014) In other words, this LSD user experienced altered perception and not necessarily hallucination. While the degree and form of this effect would depend obviously on the dose, this view of altered perception is reinforced by the current trend in "microdosing" (Rifkin, Maraver, & Colzato, 2020). A microdose is less than 20 mcg, or roughly one-tenth of the recreational LSD dose. ...
A general assumption in lysergic acid diethylamide (LSD) research is that LSD’s experiential effects are basically hallucinatory, varying in the degree of distortion. This likely derives from the widely and perhaps implicitly held position of indirect realism which, though accepting an objective world, assumes the brain is generating within the mind not only imaginative images and memory images but also perceptual images—with no substantive difference in their qualia. However, the origin of perceptual images permeated with qualia is an aspect of the “hard problem” of consciousness. And without a solution to the origin of images, any theory of LSD’s seemingly distorted images of the perceptual world is ungrounded. Currently, a model describing LSD’s perceptual effects in terms of direct perception is created by joining Henri Bergson’s panpsychism and J. J. Gibson’s ecological optics. In this model, different doses of LSD produce different timescale changes in perception, and these changes are veridical specifications of the external world, not hallucinatory. In this context, the brain is a very concrete dynamical device, one not captured by an abstract computational framework. A testable model is proposed by which LSD increases rate processes on the relevant timescale. A variety of biochemical data are argued as being productively understood in the context of Gilbert Ling’s association-induction hypothesis, and a primary sequence analysis of the “inductive index”—an amino acid score that is central to this hypothesis— is consistent with the importance of 5-hydroxytryptamine receptor 2A. The proposed model is compared to recent progress in structural biology.
... Conversely, the investigation of microdosing has shown increases in subjective cognition, including memory and attention, and other behavioral measures of cognitive functioning (Cameron et al., 2020;Family et al., 2020;Hutten et al., 2020;Lea et al., 2020;Prochazkova et al., 2018). Microdosing has also been associated with cognitive and emotional enhancement potentially due to increases in neural plasticity, neurogenesis, and decreases in neuroinflammation (Rifkin et al., 2020). Similarly, subacute effects and chronic use of psychedelics are associated with increased subjective and behavioral cognitive performance (Bouso et al., 2015(Bouso et al., , 2012Murphy-Beiner and Soar, 2020;Uthaug et al., 2018). ...
The therapeutic use of classical psychedelic substances such as d-lysergic acid diethylamide (LSD) surged in recent years. Studies in rodents suggest that these effects are produced by increased neural plasticity, including stimulation of the mTOR pathway, a key regulator of metabolism, plasticity, and aging. Could psychedelic-induced neural plasticity be harnessed to enhance cognition? Here we show that LSD treatment enhanced performance in a novel object recognition task in rats, and in a visuo-spatial memory task in humans. A proteomic analysis of human brain organoids showed that LSD affected metabolic pathways associated with neural plasticity, including mTOR. To gain insight into the relation of neural plasticity, aging and LSD-induced cognitive gains, we emulated the experiments in rats and humans with a neural network model of a cortico-hippocampal circuit. Using the baseline strength of plasticity as a proxy for age and assuming an increase in plasticity strength related to LSD dose, the simulations provided a good fit for the experimental data. Altogether, the results suggest that LSD has nootropic effects.
... Kuypers et al. 2019;Passie 2019; Hardon 2021) also as a form of cognitive enhancement(Johnstad 2018;Prochazkova et al. 2018; Hupli et al. 2019a;Rifkin, Maraver & Colzato 2020;Liokaftos 2021).Part of our "descriptive assemblage"(Savage 2007) of microdosing psychedelics on Youtube (Hupli et al. 2019a) was to give a brief overview of published and ongoing research projects in relation to microdosing psychedelics. Several publications and research projects have appeared since that publication, a few of which are presented below. ...
This article-based dissertation focuses on the sociology of cognitive enhancement drugs from mainly student users’ perspectives. The research material consists of qualitative interview data, a patient case study, a general review of available prevalence data on stimulants and a netnographic study on Youtube (Hupli et al. 2016; 2019ab; Hupli 2018a; 2020a).
Two interview studies (Hupli et al. 2016; 2019b, see Table 1) using ‘crowded theory’ to analyse separate qualitative data sets (N=35) and an online survey (N=113) showed that young students in the Netherlands and Lithuania had experienced a variety of positive and negative effects from using several legalised and illegalised drugs considered as “cognitive enhancers” in order to improve their life situations. The experiences and motivations of both self-reportedly diagnosed and those who did not report a psychiatric diagnosis did not differentiate to a large extent, empirically showcasing how the line between therapeutic and enhancement use is often blurred. Unrepresentative data sample and reliance on self-reports in terms of psychiatric diagnostics and drug effects limits the generalisability of the empirical findings and call for further study in this area in different country contexts.
By comparing statistical data from Finland and the Netherlands (Hupli 2020a) - using available data sets from international, European and national sources in relation to both medical and extra-medical use of stimulants among young people - a general review study revealed differentiating stimulant use trends between the countries. However, the full scope of these differences is challenging to evaluate especially in relation to cognitive enhancement drug use, as there is a chronic lack of research data, or even policy discussion in Finland compared to the Netherlands on this particular user practice.
To track new drug trends among young people by applying novel digital methods, a netnographic study on Youtube™ focused on a user practice called microdosing psychedelics (Hupli et al. 2019a). While the positive effects and dosing regimens mentioned in the six most viewed videos that were analysed require further critical evaluation, contrary to how typical users of illegalised drugs are often portrayed in the general media and science, these videos revolved around themes such as experiments, self-monitoring and the imperative of sharing research results. As microdosing psychedelics is seemingly a growing drug trend according to increasing Youtube video content and other media publications as well as scientific research, part of this PhD summary article will provide an update on microdosing psychedelics research especially in relation to cognitive enhancement. Cannabis as a potential cognitive enhancer is also briefly discussed.
Psychedelics and cannabinoids are rarely discussed in the pharmacological neuroenhancement literature, and therapeutic research into these compounds has been severely restricted until recently. One of the studies in this dissertation (Hupli 2018a) includes the first medical sociological patient case study of a male patient living in Finland with Attention Deficit/Hyperactivity Disorder (ADHD) who was prescribed cannabinoid therapeutics (Bedrocan®, Bediol®) to treat his ADHD as the primary indication. The case study partly confirmed increasing research into the potential of cannabinoid therapeutics for treatment-resistant conditions, including adults suffering from ADHD, although further studies and health policy reform are required in the rapidly growing field of cannabinoids in medicine.
The findings of this dissertation raise several bioethical and drug policy questions about the blurred line between pharmacological therapy and neuroenhancement, as well as the political and social dichotomy between prohibited versus promoted drugs. Using Science and Technology Studies (STS), critical drug studies and Anthropology of Pharmaceuticals literature, the author theoretically frames all classes of drugs as ‘pharmacological neurotechnologies’ in order to move beyond these dichotomies and to further develop sociology of technology and drugs. The sociological concepts of medicalisation and especially pharmaceuticalisation are discussed with a focus on the parallel development of the diagnosis of ADHD and the use of pharmacology in its treatment. The last chapter offers research and policy recommendations for evidence-based drug policy making and presents some politicogenic drug effects of current drug policing.
... Outside of the clinical realm, psychedelics appear to change social and political beliefs (Nour et al. 2017;Forstmann and Sagioglou 2017;Rifkin et al. 2020) and moral decision-making (Pokorny et al. 2020). However, disagreement remains about the locus of these effects in terms of perceptual and cognitive mechanisms (Pokorny et al. 2020), or if belief change even occurs (Johnson and Yaden 2020). ...
Renewed interest in psychedelics has reignited the debate about whether and how they change human beliefs. In both the clinical and social-cognitive domains, psychedelic consumption may be accompanied by profound, and sometimes lasting, belief changes. We review these changes and their possible underlying mechanisms. Rather than inducing de novo beliefs, we argue psychedelics may instead change the impact of affect and of others' suggestions on how beliefs are imputed. Critically , we find that baseline beliefs (in the possible effects of psychedelics, for example) might color the acute effects of psychedelics as well as longer-term changes. If we are to harness the apparent potential of psychedelics in the clinic and for human flourishing more generally, these possibilities must be addressed empirically.
... Alexithymia items suggested that difficulty describing one's emotional experience might parallel the difficulties inherent in describing the subjective effects of psychedelics (Barrett et al., 2015). The idea that psychedelic therapy might improve the ability to identify and articulate emotions has intuitive appeal given established links to emotional breakthroughs (Roseman et al., 2019) and emotional enhancements (Rifkin, Maraver, & Colzato, 2020), though clinical work currently does not focus on this skill. Given established links among alexithymia, depression, and anxiety (Marchesi, Brusamonti, & Maggini, 2000), this result echoes other calls for extending clinical trials to anxiety disorders (Muttoni, Ardissino, & John, 2019). ...
Background and aims
Multiple laboratories have proposed measures of subjective effects of psychedelics as potential mediators of their therapeutic impact. Other work has identified individual differences that covary with subjective responses in informative ways. The range of potential measures of responses, traits, and outcomes is vast. Ideas for new measures are likely numerous. The field will progress efficiently if proposed new scales can add incremental validity. Semantic Scale Network analyses identify conceptual overlap among scales based on items (rather than participant ratings), which could help laboratories avoid putting effort into measures that are unlikely to account for unique variance. Semantic Scale Network analyses can also reveal links to constructs from disparate research literatures, potentially helping investigators generate novel hypotheses and explain connections among disparate findings. The results of Semantic Scale Network analyses have the potential to improve as more investigators enter their scales into the corpus.
Method
Example analyses using the revised Mystical Experiences Questionnaire (MEQ) underscore the uniqueness and discriminant validity of the MEQ subscales.
Results
Findings dovetail with published theorizing and suggest potentially novel links with different therapeutic effects. The MEQ total or subscales overlap with measures of awe, inspiration, regret, dissatisfaction, transcendence, depression, fatigue, and spirituality. Links with measures of stress, alexithymia, and gender identity suggest lines of further work.
Conclusions
This analytic approach might suggest unique applications for psychedelic-assisted treatments and provide perspectives on phenomena outside the field. As psychedelic researchers enter their scales to the corpus for Semantic Scale Network analyses, the field will benefit.
... Although social science research has already begun to examine the experimental use of microdosing as self-therapy for mental health issues ( Lea et al., 2020b ), it would be important to trace whether microdosing becomes part of formalised therapeutic protocols ( Nutt, Erritzoe & Carhart-Harris, 2020 ) and how this could impact on its other uses, including enhancement. Equally importantly, qualitative sociological research could pursue issues around the long-term or perhaps lifelong effects of microdosing that have already been pointed out in previous research as key unknowns at present ( Rifkin, Maraver & Colzato, 2020 ). b) Contribute to the empirical and theoretical elaboration of HEDs. ...
Microdosing psychedelics is the regular use of sub-perceptive threshold doses of substances such as lysergic acid diethylamide (LSD) and psilocybin (‘magic’) mushrooms. The phenomenon has attracted increasing public and scientific attention in numerous countries in recent years. This commentary looks at microdosing psychedelics as an emerging facet of human enhancement through drugs. After presenting a narrative based on a multidisciplinary body of literature on human enhancement drugs and microdosing, the commentary maps out directions for further sociological studies of the phenomenon as well as outlining the different fields such research can contribute to.
... More recently, somewhat circumnavigating the hurdle of deeply altered states of consciousness, the concept of "microdosing" has emerged, which consists in taking a "dose of drug that is 1% of the pharmacologically active dose, up to a maximum of 100 mg" (Tewari and Mukherjee, 2010). This kind of dosage is well below the "psychedelic threshold," eliciting minimal or no psychoactive effects, and it is mostly sought for cognitive and emotional enhancement (Hutten et al., 2019;Rifkin et al., 2020) or by patients who are dissatisfied with conventional treatments to improve mental health or cease prescription or illegal substance use (Hutten et al., 2019;Lea et al., 2020). Despite the lack of systematic studies investigating beneficial outcomes and potential long-term side effects of microdosing, a growing number of individuals are seeking this alternative therapeutic approach, sometimes believing it might be a universal remedy for all somatic and psychological ailments. ...
Mounting evidence suggests safety and efficacy of psychedelic compounds as potential novel therapeutics in psychiatry. Ketamine has been approved by the Food and Drug Administration in a new class of antidepressants, and 3,4-methylenedioxymethamphetamine (MDMA) is undergoing phase III clinical trials for post-traumatic stress disorder. Psilocybin and lysergic acid diethylamide (LSD) are being investigated in several phase II and phase I clinical trials. Hence, the concept of psychedelics as therapeutics may be incorporated into modern society. Here, we discuss the main known neurobiological therapeutic mechanisms of psychedelics, which are thought to be mediated by the effects of these compounds on the serotonergic (via 5-HT2A and 5-HT1A receptors) and glutamatergic [via N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors] systems. We focus on 1) neuroplasticity mediated by the modulation of mammalian target of rapamycin–, brain-derived neurotrophic factor–, and early growth response–related pathways; 2) immunomodulation via effects on the hypothalamic-pituitary-adrenal axis, nuclear factor ĸB, and cytokines such as tumor necrosis factor-α and interleukin 1, 6, and 10 production and release; and 3) modulation of serotonergic, dopaminergic, glutamatergic, GABAergic, and norepinephrinergic receptors, transporters, and turnover systems. We discuss arising concerns and ways to assess potential neurobiological changes, dependence, and immunosuppression. Although larger cohorts are required to corroborate preliminary findings, the results obtained so far are promising and represent a critical opportunity for improvement of pharmacotherapies in psychiatry, an area that has seen limited therapeutic advancement in the last 20 years. Studies are underway that are trying to decouple the psychedelic effects from the therapeutic effects of these compounds.
Significance Statement
Psychedelic compounds are emerging as potential novel therapeutics in psychiatry. However, understanding of molecular mechanisms mediating improvement remains limited. This paper reviews the available evidence concerning the effects of psychedelic compounds on pathways that modulate neuroplasticity, immunity, and neurotransmitter systems. This work aims to be a reference for psychiatrists who may soon be faced with the possibility of prescribing psychedelic compounds as medications, helping them assess which compound(s) and regimen could be most useful for decreasing specific psychiatric symptoms.
The history of psychedelia within the New Left counterculture often implies a cultural alignment between psychedelics and progressive values or the promise of radical communitarian social reform. In contrast to these potentials, this paper examines Silicon Valley’s engagement with psychedelics, a community which has demonstrated considerable financial and personal interests in these drugs despite promoting and advancing consistently neoliberal ends. This article studies Silicon Valley’s culture of psychedelic drug use through extensive analysis of published interviews by tech industrialists, news reports, and recent studies on the tech industry’s proliferation of mystical and utopian rhetoric. This work finds that psychedelics and their associated practices are given unconventional mystical meanings by some high-profile tech entrepreneurs, and that these meanings are integrated into belief systems and philosophies which are explicitly anti-democratic, individualist, and essentialist. It is argued that these mystical ideas are supported by a venture capital community which profits from the expression of disruptive utopian beliefs. These beliefs, when held by the extremely wealthy, have effects on legalization policy and the ways which psychedelics are commercialized within a legal marketplace. As Silicon Valley has put considerable resources into funding research and advocacy for psychedelics, I argue that the legalization of psychedelics will likely be operationalized to generate a near-monopoly on the market and promote further inequality in the United States that is reflective of both neoliberalism, and the essentialist beliefs of Silicon Valley functionaries.
Abnormal neuronal and synaptic plasticity occurs in Alzheimer's disease (AD) and depression. The latter, particularly late-life, has been recognized as fundamental in the identification of at-risk prodromal stages of AD. The lack of disease-modifying drugs and the off-label use of antipsychotics and antidepressants for neuropsychiatric symptoms (NPSs) have caused a season of therapeutic inappropriateness. To date, the wealth of clinical trials investigating drugs, diverse for structure and mechanism of action, has failed to provide a cure for all the spectrums of NPSs. Psychedelics in microdosing afford promotion of neurogenesis and synaptic plasticity and, recently, have been considered a revolution for the management of depression endowed with faster action and an improved side effect profile than antidepressants. In the current scenario, therefore, the rapid-acting antidepressant esketamine could represent the first-in-class for treatment of NPSs, and this deserves to be demonstrated with an open-label clinical trial.
Background
In the past few years, the issue of ‘microdosing’ psychedelics has been openly discussed in the public arena where claims have been made about their positive effect on mood state and cognitive processes such as concentration. However, there are very few scientific studies that have specifically addressed this issue, and there is no agreed scientific consensus on what microdosing is.
Aim
This critique paper is designed to address questions that need to be answered by future scientific studies and to offer guidelines for these studies.
Approach
Owing to its proximity for a possible approval in clinical use and short-lasting pharmacokinetics, our focus is predominantly on psilocybin. Psilocybin is allegedly, next to lysergic acid diethylamide (LSD), one of the two most frequently used psychedelics to microdose. Where relevant and available, data for other psychedelic drugs are also mentioned.
Conclusion
It is concluded that while most anecdotal reports focus on the positive experiences with microdosing, future research should also focus on potential risks of (multiple) administrations of a psychedelic in low doses. To that end, (pre)clinical studies including biological (e.g. heart rate, receptor turnover and occupancy) as well as cognitive (e.g. memory, attention) parameters have to be conducted and will shed light on the potential negative consequences microdosing could have.
Background: Microdosing psychedelics is the practice of consuming very low, sub-hallucinogenic doses of a psychedelic substance, such as lysergic acid diethylamide (LSD) or psilocybin-containing mushrooms. According to media reports, microdosing has grown in popularity, yet the scientific literature contains minimal research on this practice. There has been limited reporting on adverse events associated with microdosing, and the experiences of microdosers in community samples have not been categorized.
Methods: In the present study we develop a codebook of Microdosing Benefits and Challenges (MDBC) based on the qualitative reports of a real-world sample of 278 microdosers.
Results: We describe novel findings, both in terms of beneficial outcomes, such as improved mood (26.6%) and focus (14.8%), and in terms of challenging outcomes, such as physiological discomfort (18.0%) and increased anxiety (6.7%). We also show parallels between benefits and drawbacks and discuss the implications of these results. We probe for substance-dependent differences, finding that psilocybin-only users report the benefits of microdosing were more important than other users report.
Conclusions: These mixed-methods results help summarize and frame the experiences reported by an active microdosing community as high-potential avenues for future scientific research. The MDBC taxonomy reported here informs future research, leveraging participant reports to distill the highest-potential intervention targets so research funding can be efficiently allocated. Microdosing research complements the full-dose literature as clinical treatments are developed and neuropharmacological mechanisms are sought. This framework aims to inform researchers and clinicians as experimental microdosing research begins in earnest in the years to come.
Keywords: psychedelic, microdosing, LSD, psilocybin, grounded theory, mood, depression, anxiety, self-efficacy, open science
Background
5-methoxy-N,N-dimethyltryptamine (hereinafter referred to as 5-MeO-DMT) is a psychedelic substance found in the secretion from the parotoid glands of the Bufo alvarius toad. Inhalation of vapor from toad secretion containing 5-MeO-DMT has become popular in naturalistic settings as a treatment of mental health problems or as a means for spiritual exploration. However, knowledge of the effects of 5-MeO-DMT in humans is limited.
Aims
The first objective of this study was to assess sub-acute and long-term effects of inhaling vapor from dried toad secretion containing 5-MeO-DMT on affect and cognition. The second objective was to assess whether any changes were associated with the psychedelic experience.
Methods
Assessments at baseline, within 24 h and 4 weeks following intake, were made in 42 individuals who inhaled vapor from dried toad secretion at several European locations.
Results
Relative to baseline, ratings of satisfaction with life and convergent thinking significantly increased right after intake and were maintained at follow-up 4 weeks later. Ratings of mindfulness also increased over time and reached statistical significance at 4 weeks. Ratings of depression, anxiety, and stress decreased after the session, and reached significance at 4 weeks. Participants that experienced high levels of ego dissolution or oceanic boundlessness during the session displayed higher ratings of satisfaction with life and lower ratings of depression and stress.
Conclusion
A single inhalation of vapor from dried toad secretion containing 5-MeO-DMT produces sub-acute and long-term changes in affect and cognition in volunteers. These results warrant exploratory research into therapeutic applications of 5-MeO-DMT.
Drugs capable of ameliorating symptoms of depression and anxiety while also improving cognitive function and sociability are highly desirable. Anecdotal reports have suggested that serotonergic psychedelics administered in low doses on a chronic, intermittent schedule, so-called "microdosing", might produce beneficial effects on mood, anxiety, cognition, and social interaction. Here, we test this hypothesis by subjecting male and female Sprague Dawley rats to behavioral testing following the chronic, intermittent administration of low doses of the psychedelic N, N-dimethyltryptamine (DMT). The behavioral and cellular effects of this dosing regimen were distinct from those induced following a single high dose of the drug. We found that chronic, intermittent, low doses of DMT produced an antidepressant-like phenotype and enhanced fear extinction learning without impacting working memory or social interaction. Additionally, male rats treated with DMT on this schedule gained a significant amount of body weight during the course of the study. Taken together, our results suggest that psychedelic microdosing may alleviate symptoms of mood and anxiety disorders, though the potential hazards of this practice warrant further investigation.
Creative thinking and empathy are crucial for everyday interactions and subjective well-being. This is emphasized by studies showing a reduction in these skills in populations where social interaction and subjective well-being are significantly compromised (e.g., depression). Anecdotal reports and recent studies suggest that a single administration of psilocybin can enhance such processes and could therefore be a potential treatment. However, it has yet to be assessed whether effects outlast acute intoxication. The present study aimed to assess the sub-acute effects of psilocybin on creative thinking, empathy, and well-being. Participants attending a psilocybin retreat completed tests of creative (convergent and divergent) thinking and empathy, and the satisfaction with life scale on three occasions: before ingesting psilocybin (N = 55), the morning after (N = 50), and seven days after (N = 22). Results indicated that psilocybin enhanced divergent thinking and emotional empathy the morning after use. Enhancements in convergent thinking, valence-specific emotional empathy, and well-being persisted seven days after use. Sub-acute changes in empathy correlated with changes in well-being. The study demonstrates that a single administration of psilocybin in a social setting may be associated with sub-acute enhancement of creative thinking, empathy, and subjective well-being. Future research should test whether these effects contribute to the therapeutic effects in clinical populations.
The phenomenon of ‘microdosing’, that is, regular ingestion of very small quantities of psychedelic substances, has seen a rapid explosion of popularity in recent years. Individuals who microdose report minimal acute effects from these substances yet claim a range of long-term general health and wellbeing benefits. There have been no published empirical studies of microdosing and the current legal and bureaucratic climate makes direct empirical investigation of the effects of psychedelics difficult. In Study One we conducted a systematic, observational investigation of individuals who microdose. We tracked the experiences of 98 microdosing participants, who provided daily ratings of psychological functioning over a six week period. 63 of these additionally completed a battery of psychometric measures tapping mood, attention, wellbeing, mystical experiences, personality, creativity, and sense of agency, at baseline and at completion of the study. Analyses of daily ratings revealed a general increase in reported psychological functioning across all measures on dosing days but limited evidence of residual effects on following days. Analyses of pre and post study measures revealed reductions in reported levels of depression and stress; lower levels of distractibility; increased absorption; and increased neuroticism. To better understand these findings, in Study Two we investigated pre-existing beliefs and expectations about the effects of microdosing in a sample of 263 naïve and experienced microdosers, so as to gauge expectancy bias. All participants believed that microdosing would have large and wide-ranging benefits in contrast to the limited outcomes reported by actual microdosers. Notably, the effects believed most likely to change were unrelated to the observed pattern of reported outcomes. The current results suggest that dose controlled empirical research on the impacts of microdosing on mental health and attentional capabilities are needed.
Rationale
Microdosing psychedelics—the regular consumption of small amounts of psychedelic substances such as LSD or psilocybin—is a growing trend in popular culture. Recent studies on full-dose psychedelic psychotherapy reveal promising benefits for mental well-being, especially for depression and end-of-life anxiety. While full-dose therapies include perception-distorting properties, microdosing mayprovide complementary clinical benefits using lower-risk, non-hallucinogenic doses.
Objectives
This pre-registered study aimed to investigate whether microdosing psychedelics is related to differences in personality, mental health, and creativity.
Methods
In this observational study, respondents recruited from online forums self-reported their microdosing behaviors and completed questionnaires concerning dysfunctional attitudes, wisdom, negative emotionality, open-mindedness, and mood. Respondents also performed the Unusual Uses Task to assess their creativity.
Results
Current and former microdosers scored lower on measures of dysfunctional attitudes (p < 0.001, r = − 0.92) and negative emotionality (p = 0.009, r = − 0.85) and higher on wisdom (p < 0.001, r = 0.88), openmindedness(p = 0.027, r = 0.67), and creativity (p < 0.001, r = 0.15) when compared to non-microdosing controls.
Conclusions
These findings provide promising initial evidence that warrants controlled experimental research to directly test safety and clinical efficacy. As microdoses are easier to administer than full-doses, this new paradigm has the exciting potential to shape future psychedelic research.
Rationale
Previous research demonstrating that lysergic acid diethylamide (LSD) produces alterations in time perception has implications for its impact on conscious states and a range of psychological functions that necessitate precise interval timing. However, interpretation of this research is hindered by methodological limitations and an inability to dissociate direct neurochemical effects on interval timing from indirect effects attributable to altered states of consciousness.
Methods
We conducted a randomised, double-blind, placebo-controlled study contrasting oral administration of placebo with three microdoses of LSD (5, 10, and 20 μg) in older adults. Subjective drug effects were regularly recorded and interval timing was assessed using a temporal reproduction task spanning subsecond and suprasecond intervals.
Results
LSD conditions were not associated with any robust changes in self-report indices of perception, mentation, or concentration. LSD reliably produced over-reproduction of temporal intervals of 2000 ms and longer with these effects most pronounced in the 10 μg dose condition. Hierarchical regression analyses indicated that LSD-mediated over-reproduction was independent of marginal differences in self-reported drug effects across conditions.
Conclusions
These results suggest that microdose LSD produces temporal dilation of suprasecond intervals in the absence of subjective alterations of consciousness.
Classic psychedelics are substances of paramount cultural and neuroscientific importance. A distinctive feature of psychedelic drugs is the wide range of potential subjective effects they can elicit, known to be deeply influenced by the internal state of the user (“set”) and the surroundings (“setting”). The observation of cross-tolerance and a series of empirical studies in humans and animal models support agonism at the serotonin (5-HT)2A receptor as a common mechanism for the action of psychedelics. The diversity of subjective effects elicited by different compounds has been attributed to the variables of “set” and “setting,” to the binding affinities for other 5-HT receptor subtypes, and to the heterogeneity of transduction pathways initiated by conformational receptor states as they interact with different ligands (“functional selectivity”). Here we investigate the complementary (i.e., not mutually exclusive) possibility that such variety is also related to the binding affinity for a range of neurotransmitters and monoamine transporters including (but not limited to) 5-HT receptors. Building on two independent binding affinity datasets (compared to “in silico” estimates) in combination with natural language processing tools applied to a large repository of reports of psychedelic experiences (Erowid’s Experience Vaults), we obtained preliminary evidence supporting that the similarity between the binding affinity profiles of psychoactive substituted phenethylamines and tryptamines is correlated with the semantic similarity of the associated reports. We also showed that the highest correlation was achieved by considering the combined binding affinity for the 5-HT, dopamine (DA), glutamate, muscarinic and opioid receptors and for the Ca+ channel. Applying dimensionality reduction techniques to the reports, we linked the compounds, receptors, transporters and the Ca+ channel to distinct fingerprints of the reported subjective effects. To the extent that the existing binding affinity data is based on a low number of displacement curves that requires further replication, our analysis produced preliminary evidence consistent with the involvement of different binding sites in the reported subjective effects elicited by psychedelics. Beyond the study of this particular class of drugs, we provide a methodological framework to explore the relationship between the binding affinity profiles and the reported subjective effects of other psychoactive compounds.
Introduction
Taking microdoses (a mere fraction of normal doses) of psychedelic substances, such as truffles, recently gained popularity, as it allegedly has multiple beneficial effects including creativity and problem-solving performance, potentially through targeting serotonergic 5-HT2A receptors and promoting cognitive flexibility, crucial to creative thinking. Nevertheless, enhancing effects of microdosing remain anecdotal, and in the absence of quantitative research on microdosing psychedelics, it is impossible to draw definitive conclusions on that matter. Here, our main aim was to quantitatively explore the cognitive-enhancing potential of microdosing psychedelics in healthy adults.
Methods
During a microdosing event organized by the Dutch Psychedelic Society, we examined the effects of psychedelic truffles (which were later analyzed to quantify active psychedelic alkaloids) on two creativity-related problem-solving tasks: the Picture Concept Task assessing convergent thinking and the Alternative Uses Task assessing divergent thinking. A short version of the Ravens Progressive Matrices task assessed potential changes in fluid intelligence. We tested once before taking a microdose and once while the effects were expected to be manifested.
Results
We found that both convergent and divergent thinking performance was improved after a non-blinded microdose, whereas fluid intelligence was unaffected.
Conclusion
While this study provides quantitative support for the cognitive-enhancing properties of microdosing psychedelics, future research has to confirm these preliminary findings in more rigorous placebo-controlled study designs. Based on these preliminary results, we speculate that psychedelics might affect cognitive metacontrol policies by optimizing the balance between cognitive persistence and flexibility. We hope this study will motivate future microdosing studies with more controlled designs to test this hypothesis.
The subgranular zone (SGZ) of dentate gyrus (DG) is one of the few regions in which neurogenesis is maintained throughout adulthood. It is believed that newborn neurons in this region encode temporal information about partially overlapping contextual memories. The 5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a naturally occurring compound capable of inducing a powerful psychedelic state. Recently, it has been suggested that DMT analogs may be used in the treatment of mood disorders. Due to the strong link between altered neurogenesis and mood disorders, we tested whether 5-MeO-DMT is capable of increasing DG cell proliferation. We show that a single intracerebroventricular (ICV) injection of 5-MeO-DMT increases the number of Bromodeoxyuridine (BrdU+) cells in adult mice DG. Moreover, using a transgenic animal expressing tamoxifen-dependent Cre recombinase under doublecortin promoter, we found that 5 Meo-DMT treated mice had a higher number of newborn DG Granule cells (GC). We also showed that these DG GC have more complex dendritic morphology after 5-MeO-DMT. Lastly, newborn GC treated with 5-MeO-DMT, display shorter afterhyperpolarization (AHP) potentials and higher action potential (AP) threshold compared. Our findings show that 5-MeO-DMT affects neurogenesis and this effect may contribute to the known antidepressant properties of DMT-derived compounds.
Near-death experiences (NDEs) are complex subjective experiences, which have been previously associated with the psychedelic experience and more specifically with the experience induced by the potent serotonergic, N,N-Dimethyltryptamine (DMT). Potential similarities between both subjective states have been noted previously, including the subjective feeling of transcending one's body and entering an alternative realm, perceiving and communicating with sentient 'entities' and themes related to death and dying. In this within-subjects placebo-controled study we aimed to test the similarities between the DMT state and NDEs, by administering DMT and placebo to 13 healthy participants, who then completed a validated and widely used measure of NDEs. Results revealed significant increases in phenomenological features associated with the NDE, following DMT administration compared to placebo. Also, we found significant relationships between the NDE scores and DMT-induced ego-dissolution and mystical-type experiences, as well as a significant association between NDE scores and baseline trait 'absorption' and delusional ideation measured at baseline. Furthermore, we found a significant overlap in nearly all of the NDE phenomenological features when comparing DMT-induced NDEs with a matched group of 'actual' NDE experiencers. These results reveal a striking similarity between these states that warrants further investigation.
Rationale
Ayahuasca is a psychotropic plant tea from South America used for religious purposes by indigenous people of the Amazon. Increasing evidence indicates that ayahuasca may have therapeutic potential in the treatment of mental health disorders and can enhance mindfulness-related capacities. Most research so far has focused on acute and sub-acute effects of ayahuasca on mental health-related parameters and less on long-term effects.
Objectives
The present study aimed to assess sub-acute and long-term effects of ayahuasca on well-being and cognitive thinking style. The second objective was to assess whether sub-acute and long-term effects of ayahuasca depend on the degree of ego dissolution that was experienced after consumption of ayahuasca.
Results
Ayahuasca ceremony attendants (N = 57) in the Netherlands and Colombia were assessed before, the day after, and 4 weeks following the ritual. Relative to baseline, ratings of depression and stress significantly decreased after the ayahuasca ceremony and these changes persisted for 4 weeks. Likewise, convergent thinking improved post-ayahuasca ceremony up until the 4 weeks follow-up. Satisfaction with life and several aspects of mindfulness increased the day after the ceremony, but these changes failed to reach significance 4 weeks after. Changes in affect, satisfaction with life, and mindfulness were significantly correlated to the level of ego dissolution experienced during the ayahuasca ceremony and were unrelated to previous experience with ayahuasca.
Conclusion
It is concluded that ayahuasca produces sub-acute and long-term improvements in affect and cognitive thinking style in non-pathological users. These data highlight the therapeutic potential of ayahuasca in the treatment of mental health disorders, such as depression.
Objective
To explore whether psilocybin with psychological support modulates personality parameters in patients suffering from treatment‐resistant depression (TRD).
Method
Twenty patients with moderate or severe, unipolar, TRD received oral psilocybin (10 and 25 mg, one week apart) in a supportive setting. Personality was assessed at baseline and at 3‐month follow‐up using the Revised NEO Personality Inventory (NEO‐PI‐R), the subjective psilocybin experience with Altered State of Consciousness (ASC) scale, and depressive symptoms with QIDS‐SR16.
Results
Neuroticism scores significantly decreased while Extraversion increased following psilocybin therapy. These changes were in the direction of the normative NEO‐PI‐R data and were both predicted, in an exploratory analysis, by the degree of insightfulness experienced during the psilocybin session. Openness scores also significantly increased following psilocybin, whereas Conscientiousness showed trend‐level increases, and Agreeableness did not change.
Conclusion
Our observation of changes in personality measures after psilocybin therapy was mostly consistent with reports of personality change in relation to conventional antidepressant treatment, although the pronounced increases in Extraversion and Openness might constitute an effect more specific to psychedelic therapy. This needs further exploration in future controlled studies, as do the brain mechanisms of postpsychedelic personality change.
Atrophy of neurons in the prefrontal cortex (PFC) plays a key role in the pathophysiology of depression and related disorders. The ability to promote both structural and functional plasticity in the PFC has been hypothesized to underlie the fast-acting antidepressant properties of the dissociative anesthetic ketamine. Here, we report that, like ketamine, serotonergic psychedelics are capable of robustly increasing neuritogenesis and/or spinogenesis both in vitro and in vivo. These changes in neuronal structure are accompanied by increased synapse number and function, as measured by fluorescence microscopy and electrophysiology. The structural changes induced by psychedelics appear to result from stimulation of the TrkB, mTOR, and 5-HT2A signaling pathways and could possibly explain the clinical effectiveness of these compounds. Our results underscore the therapeutic potential of psychedelics and, importantly, identify several lead scaffolds for medicinal chemistry efforts focused on developing plasticity-promoting compounds as safe, effective, and fast-acting treatments for depression and related disorders.
Short-term moderate doses of serotonergic and dissociative hallucinogens can be useful in the treatment of anxiety. Recently, a trend has developed for long-term intermittent 'microdosing' (usually one-tenth of a 'full' active dose), with reports of long-lasting relief from anxiety and related disorders; however, there is no scientific evidence for the efficacy of therapeutic microdosing nor to show its lasting effects. The objective of this study was to test for lasting effects on anxiety in rats after microdosing with ketamine or psilocin. Over 6 days, Wistar rats (N=40) were administered ketamine (0.5 or 3 mg/kg), psilocin (0.05 or 0.075 mg/kg), or saline on three occasions. A 5-min elevated plus-maze test was conducted 48 h after the final drug treatment (n=8). Dependent variables were entries (frequency), spent time (%), and distance traveled (cm) in each zone, as well as total frequency of rears, stretch-attend postures, and head dips. Statistical analyses of drug effects used separate independent one-way analysis of variance and pair-wise comparisons using independent t-tests. Statistical effects were modest or borderline and were most consistent with a mildly anxiogenic profile, which was significant at lower doses; however, this conclusion remains tentative. The lower doses of ketamine and psilocin produced comparable effects (to one another) across each variable, as did the higher doses. This pattern of effects may suggest a common (e.g. neurotransmitter/receptor) mechanism. We conclude that microdosing with hallucinogens for therapeutic purposes might be counter-productive; however, more research is needed to confirm our findings and to establish their translational relevance to clinical 'psychedelic' therapy.
The purpose of this commentary is to provide an introduction to this special issue of Neuropharmacology with a historical perspective of psychedelic drug research, their use in psychiatric disorders, research-restricting regulatory controls, and their recent emergence as potential breakthrough therapies for several brain-related disorders. It begins with the discovery of lysergic acid diethylamide (LSD) and its promising development as a treatment for several types of mental illnesses during the 1940s. This was followed by its abuse and stigmatization in the 1960s that ultimately led to the placement of LSD and other psychedelic drugs into the most restrictively regulated drug schedule of the United States Controlled Substances Act (Schedule I) in 1970 and its international counterparts. These regulatory controls severely constrained development of psychedelic substances and their potential for clinical research in psychiatric disorders. Despite the limitations, there was continued research into brain mechanisms of action for psychedelic drugs with potential clinical applications which began during the 1990s and early 2000s. Finding pathways to accelerate clinical research in psychedelic drug development is supported by the growing body of research findings that are documented throughout this special issue of Neuropharmacology. Accumulated research to date suggests psychedelic drug assisted psychotherapy may emerge as a potential breakthrough treatment for several types of mental illnesses including depression, anxiety, post-traumatic stress disorder, and addiction that are refractory to current evidenced based therapies. This research equally shows promise in advancing the understanding of the brain, brain related functioning, and the consequential effects of untreated brain related diseases that have been implicated in causing and/or exacerbating numerous physical disease state conditions. The authors conclude that more must be done to effectively address mental illnesses and brain related diseases which have become so pervasive, destructive, and whose treatments are becoming increasingly resistant to current evidenced based therapies.
Aims:
This article presents a qualitative interview study of people who microdose with psychedelic drugs, which means that the user takes about one tenth of an ordinary recreational dose.
Design:
Respondents (n = 21) were recruited at several Internet fora for individual interviews via private messaging. Every participant was male, and the median respondent was in his 30s with a stable job and relationship and extensive entheogen experience.
Results:
Respondents tended to experiment with microdosing in phases, reporting mostly positive consequences from this form of drug use. Reported effects included improved mood, cognition, and creativity, which often served to counteract symptoms especially from conditions of anxiety and depression. There were also reports of various challenges with psychedelic microdosing, and some did not find the practice worth continuing.
Conclusion:
The study obtained evidence of a group of users taking small doses of psychedelics not for the purpose of intoxication but to enhance everyday functioning. While the study’s findings are not generalisable, they may inform subsequent investigations with research questions and hypotheses.
Psychedelic drugs are making waves as modern trials support their therapeutic potential and various media continue to pique public interest. In this opinion piece, we draw attention to a long-recognised component of the psychedelic treatment model, namely ‘set’ and ‘setting’ – subsumed here under the umbrella term ‘context’. We highlight: (a) the pharmacological mechanisms of classic psychedelics (5-HT2A receptor agonism and associated plasticity) that we believe render their effects exceptionally sensitive to context, (b) a study design for testing assumptions regarding positive interactions between psychedelics and context, and (c) new findings from our group regarding contextual determinants of the quality of a psychedelic experience and how acute experience predicts subsequent long-term mental health outcomes. We hope that this article can: (a) inform on good practice in psychedelic research, (b) provide a roadmap for optimising treatment models, and (c) help tackle unhelpful stigma still surrounding these compounds, while developing an evidence base for long-held assumptions about the critical importance of context in relation to psychedelic use that can help minimise harms and maximise potential benefits.
Neuropharmacological effects of psychedelics have profound cognitive, emotional, and social effects that inspired the development of cultures and religions worldwide. Findings that psychedelics objectively and reliably produce mystical experiences press the question of the neuropharmacological mechanisms by which these highly significant experiences are produced by exogenous neurotransmitter analogs. Humans have a long evolutionary relationship with psychedelics, a consequence of psychedelics' selective effects for human cognitive abilities, exemplified in the information rich visionary experiences. Objective evidence that psychedelics produce classic mystical experiences, coupled with the finding that hallucinatory experiences can be induced by many non-drug mechanisms, illustrates the need for a common model of visionary effects. Several models implicate disturbances of normal regulatory processes in the brain as the underlying mechanisms responsible for the similarities of visionary experiences produced by psychedelic and other methods for altering consciousness. Similarities in psychedelic-induced visionary experiences and those produced by practices such as meditation and hypnosis and pathological conditions such as epilepsy indicate the need for a general model explaining visionary experiences. Common mechanisms underlying diverse alterations of consciousness involve the disruption of normal functions of the prefrontal cortex and default mode network (DMN). This interruption of ordinary control mechanisms allows for the release of thalamic and other lower brain discharges that stimulate a visual information representation system and release the effects of innate cognitive functions and operators. Converging forms of evidence support the hypothesis that the source of psychedelic experiences involves the emergence of these innate cognitive processes of lower brain systems, with visionary experiences resulting from the activation of innate processes based in the mirror neuron system (MNS).
Previous attempts to identify a unified theory of brain serotonin function have largely failed to achieve consensus. In this present synthesis, we integrate previous perspectives with new and older data to create a novel bipartite model centred on the view that serotonin neurotransmission enhances two distinct adaptive responses to adversity, mediated in large part by its two most prevalent and researched brain receptors: the 5-HT1A and 5-HT2A receptors. We propose that passive coping (i.e. tolerating a source of stress) is mediated by postsynaptic 5-HT1AR signalling and characterised by stress moderation. Conversely, we argue that active coping (i.e. actively addressing a source of stress) is mediated by 5-HT2AR signalling and characterised by enhanced plasticity (defined as capacity for change). We propose that 5-HT1AR-mediated stress moderation may be the brain's default response to adversity but that an improved ability to change one's situation and/or relationship to it via 5-HT2AR-mediated plasticity may also be important - and increasingly so as the level of adversity reaches a critical point. We propose that the 5HT1AR pathway is enhanced by conventional 5-HT reuptake blocking antidepressants such as the selective serotonin reuptake inhibitors (SSRIs), whereas the 5-HT2AR pathway is enhanced by 5-HT2AR-agonist psychedelics. This bipartite model purports to explain how different drugs (SSRIs and psychedelics) that modulate the serotonergic system in different ways, can achieve complementary adaptive and potentially therapeutic outcomes.
Banisteriopsis caapi is the basic ingredient of ayahuasca, a psychotropic plant tea used in the Amazon for ritual and medicinal purposes, and by interested individuals worldwide. Animal studies and recent clinical research suggests that B. caapi preparations show antidepressant activity, a therapeutic effect that has been linked to hippocampal neurogenesis. Here we report that harmine, tetrahydroharmine and harmaline, the three main alkaloids present in B. caapi, and the harmine metabolite harmol, stimulate adult neurogenesis in vitro. In neurospheres prepared from progenitor cells obtained from the subventricular and the subgranular zones of adult mice brains, all compounds stimulated neural stem cell proliferation, migration, and differentiation into adult neurons. These findings suggest that modulation of brain plasticity could be a major contribution to the antidepressant effects of ayahuasca. They also expand the potential application of B. caapi alkaloids to other brain disorders that may benefit from stimulation of endogenous neural precursor niches.
Plant-based psychedelics such as psilocybin have an ancient history of medicinal use. After the first English-language report on LSD in 1950, psychedelics enjoyed a short-lived relationship with psychology and psychiatry. Used most notably as aides to psychotherapy for the treatment of mood disorders and alcohol dependence, drugs such as LSD showed initial therapeutic promise before prohibitive legislature in the mid-1960s effectively ended all major psychedelic research programmes. Since the early 1990s, there has been a steady revival of human psychedelic research: last year saw reports on the first modern brain imaging study with LSD and 3 separate clinical trials of psilocybin for depressive symptoms. In this Circumspective piece, Robin Carhart-Harris and Guy Goodwin share their opinions on the promises and pitfalls of renewed psychedelic research, with a focus on the development of psilocybin as a treatment for depression.Neuropsychopharmacology accepted article preview online, 26 April 2017. doi:10.1038/npp.2017.84.
Lysergic acid diethylamide (LSD) induces profound changes in various mental domains, including perception, self-awareness and emotions. We used functional magnetic resonance imaging (fMRI) to investigate the acute effects of LSD on the neural substrate of emotional processing in humans. Using a double-blind, randomised, cross-over study design, placebo or 100 µg LSD were orally administered to 20 healthy subjects before the fMRI scan, taking into account the subjective and pharmacological peak effects of LSD. The plasma levels of LSD were determined immediately before and after the scan. The study (including the a priori-defined study end point) was registered at ClinicalTrials.gov before study start (NCT02308969). The administration of LSD reduced reactivity of the left amygdala and the right medial prefrontal cortex relative to placebo during the presentation of fearful faces (P<0.05, family-wise error). Notably, there was a significant negative correlation between LSD-induced amygdala response to fearful stimuli and the LSD-induced subjective drug effects (P<0.05). These data suggest that acute administration of LSD modulates the engagement of brain regions that mediate emotional processing.
Classic hallucinogens share pharmacology as serotonin 5-HT2A, 5-HT2B, and 5-HT2C receptor agonists. Unique among most other Schedule 1 drugs, they are generally non-addictive and can be effective tools in the treatment of addiction. Mechanisms underlying these attributes are largely unknown. However, many preclinical studies show that 5-HT2C agonists counteract the addictive effects of drugs from several classes, suggesting this pharmacological property of classic hallucinogens may be significant. Drawing from a comprehensive analysis of preclinical behavior, neuroanatomy, and neurochemistry studies, this review builds rationale for this hypothesis, and also proposes a testable, neurobiological framework. 5-HT2C agonists work, in part, by modulating dopamine neuron activity in the ventral tegmental area—nucleus accumbens (NAc) reward pathway. We argue that activation of 5-HT2C receptors on NAc shell, GABAergic, medium spiny neurons inhibits potassium Kv1.x channels, thereby enhancing inhibitory activity via intrinsic mechanisms. Together with experiments that show that addictive drugs, such as cocaine, potentiate Kv1.x channels, thereby suppressing NAc shell GABAergic activity, this hypothesis provides a mechanism by which classic hallucinogen-mediated stimulation of 5-HT2C receptors could thwart addiction. It also provides a potential reason for the non-addictive nature of classic hallucinogens.
Psychedelic drugs have been used as treatments in indigenous cultures for thousands of years. Yet, due to their legal status, there has been limited scientific research into the therapeutic potential of these compounds for psychiatric disorders. In the absence of other effective treatments however, researchers have begun again to systematically investigate such compounds and there is now evidence pointing to the use of psychedelic drugs in the treatment of addiction. In this review we focus on human evidence for the effectiveness of preparations used by indigenous cultures in the Amazon (ayahausca) and Africa (ibogaine) and worldwide (psilocybin), and more recently synthetised drugs such as the serotonergic hallucinogen LSD and the dissociative anaesthetic ketamine. Potential mechanisms explored are anti-depressant effects, changes in neuroplasticity and existential psychological effects of these drugs.
Experiences of profound existential or spiritual significance can be triggered reliably through psychopharmacological means using psychedelic substances. However, little is known about the benefits of religious, spiritual, or mystical experiences (RSMEs) prompted by psychedelic substances, as compared with those that occur through other means. In this study, 739 self-selected participants reported the psychological impact of their RSMEs and indicated whether they were induced by a psychedelic substance. Experiences induced by psychedelic substances were rated as more intensely mystical (d = .75, p < .001), resulted in a reduced fear of death (d = .21, p < .01), increased sense of purpose (d = .18, p < .05), and increased spirituality (d = .28, p < .001) as compared with nonpsychedelically triggered RSMEs. These results remained significant in an expanded model controlling for gender, education, socioeconomic status, and religious affiliation. These findings lend support to the growing consensus that RSMEs induced with psychedelic substances are genuinely mystical and generally positive in outcome.
Lysergic acid diethylamide (LSD) is used recreationally and has been evaluated as an adjunct to psychotherapy to treat anxiety in patients with life-threatening illness. LSD is well-known to induce perceptual alterations, but unknown is whether LSD alters emotional processing in ways that can support psychotherapy. We investigated the acute effects of LSD on emotional processing using the Face Emotion Recognition Task (FERT) and Multifaceted Empathy Test (MET). The effects of LSD on social behavior were tested using the Social Value Orientation (SVO) test. Two similar placebo-controlled, double-blind, random-order, cross-over studies were conducted using 100 μg LSD in 24 subjects and 200 μg LSD in 16 subjects. All of the subjects were healthy and mostly hallucinogen-naive 25- to 65-year-old volunteers (20 men, 20 women). LSD produced feelings of happiness, trust, closeness to others, enhanced explicit and implicit emotional empathy on the MET, and impaired the recognition of sad and fearful faces on the FERT. LSD enhanced the participants' desire to be with other people and increased their prosocial behavior on the SVO test. These effects of LSD on emotion processing and sociality may be useful for LSD-assisted psychotherapy.Neuropsychopharmacology accepted article preview online, 01 June 2016. doi:10.1038/npp.2016.82.
Significance
Lysergic acid diethylamide (LSD), the prototypical “psychedelic,” may be unique among psychoactive substances. In the decades that followed its discovery, the magnitude of its effect on science, the arts, and society was unprecedented. LSD produces profound, sometimes life-changing experiences in microgram doses, making it a particularly powerful scientific tool. Here we sought to examine its effects on brain activity, using cutting-edge and complementary neuroimaging techniques in the first modern neuroimaging study of LSD. Results revealed marked changes in brain blood flow, electrical activity, and network communication patterns that correlated strongly with the drug’s hallucinatory and other consciousness-altering properties. These results have implications for the neurobiology of consciousness and for potential applications of LSD in psychological research.
Lysergic acid diethylamide (LSD), described as a classical hallucinogen, began its journey from the middle of the last century following an accidental discovery. Since then, it was used as a popular and notorious substance of abuse in various parts of the world. Its beneficial role as an adjunct to psychotherapy was much unknown, until some ‘benevolent’ experiments were carried out over time to explore some of its potential uses. But, many of its effects were unclear and seemed to be a psychedelic enigma. In this review article, we have described the receptor pharmacology, mechanism of action, effects and adverse effects of LSD on the normal body system. We have also highlighted its addictive potentials and the chances of developing tolerance. We have assimilated some of the interesting therapeutic uses of this drug, such as an antianxiety agent, a creativity enhancer, a suggestibility enhancer, and a performance enhancer. We have also described LSD to be successfully used in drug and alcohol dependence, and as a part of psychedelic peak therapy in terminally ill patients. The relevant chronological history and literature in the light of present knowledge and scenarios have been discussed. Based on available evidence, LSD could be tried therapeutically in certain specific conditions under controlled settings. But as we mention, due to all the safety concerns, the use of this nonaddictive ‘entheogen’ in actual practice warrants a lot of expertise, caution, cooperation and ethical considerations.
Psychedelics (serotonergic hallucinogens) are powerful psychoactive substances that alter perception and mood and affect numerous cognitive processes. They are generally considered physiologically safe and do not lead to dependence or addiction. Their origin predates written history, and they were employed by early cultures in many sociocultural and ritual contexts. After the virtually contemporaneous discovery of (5R,8R)-(+)-lysergic acid-N,N-diethylamide (LSD)-25 and the identification of serotonin in the brain, early research focused intensively on the possibility that LSD and other psychedelics had a serotonergic basis for their action. Today there is a consensus that psychedelics are agonists or partial agonists at brain serotonin 5-hydroxytryptamine 2A receptors, with particular importance on those expressed on apical dendrites of neocortical pyramidal cells in layer V. Several useful rodent models have been developed over the years to help unravel the neurochemical correlates of serotonin 5-hydroxytryptamine 2A receptor activation in the brain, and a variety of imaging techniques have been employed to identify key brain areas that are directly affected by psychedelics. Recent and exciting developments in the field have occurred in clinical research, where several double-blind placebo-controlled phase 2 studies of psilocybin-assisted psychotherapy in patients with cancer-related psychosocial distress have demonstrated unprecedented positive relief of anxiety and depression. Two small pilot studies of psilocybinassisted psychotherapy also have shown positive benefit in treating both alcohol and nicotine addiction. Recently, blood oxygen level–dependent functional magnetic resonance imaging and magnetoencephalography have been employed for in vivo brain imaging in humans after administration of a psychedelic, and results indicate that intravenously administered psilocybin and LSD produce decreases in oscillatory power in areas of the brain’s default mode network. © 2016 by The American Society for Pharmacology and Experimental Therapeutics.
The serotonergic system forms a diffuse network within the central nervous system and plays a significant role in the regulation of mood and cognition. Manipulation of tryptophan levels, acutely or chronically, by depletion or supplementation, is an experimental procedure for modifying peripheral and central serotonin levels. These studies have allowed us to establish the role of serotonin in higher order brain function in both preclinical and clinical situations and have precipitated the finding that low brain serotonin levels are associated with poor memory and depressed mood. The gut-brain axis is a bi-directional system between the brain and gastrointestinal tract, linking emotional and cognitive centres of the brain with peripheral functioning of the digestive tract. An influence of gut microbiota on behaviour is becoming increasingly evident, as is the extension to tryptophan and serotonin, producing a possibility that alterations in the gut may be important in the pathophysiology of human central nervous system disorders. In this review we will discuss the effect of manipulating tryptophan on mood and cognition, and discuss a possible influence of the gut-brain axis.
Background:
Numerous anecdotal reports suggest that repeated use of very low doses of lysergic acid diethylamide (LSD), known as microdosing, improves mood and cognitive function. These effects are consistent both with the known actions of LSD on serotonin receptors and with limited evidence that higher doses of LSD (100-200 μg) positively bias emotion processing. Yet, the effects of such subthreshold doses of LSD have not been tested in a controlled laboratory setting. As a first step, we examined the effects of single very low doses of LSD (0-26 μg) on mood and behavior in healthy volunteers under double-blind conditions.
Methods:
Healthy young adults (N = 20) attended 4 laboratory sessions during which they received 0 (placebo), 6.5, 13, or 26 μg of LSD in randomized order at 1-week intervals. During expected peak drug effect, they completed mood questionnaires and behavioral tasks assessing emotion processing and cognition. Cardiovascular measures and body temperature were also assessed.
Results:
LSD produced dose-related subjective effects across the 3 doses (6.5, 13, and 26 μg). At the highest dose, the drug also increased ratings of vigor and slightly decreased positivity ratings of images with positive emotional content. Other mood measures, cognition, and physiological measures were unaffected.
Conclusions:
Single microdoses of LSD produced orderly dose-related subjective effects in healthy volunteers. These findings indicate that a threshold dose of 13 μg of LSD might be used safely in an investigation of repeated administrations. It remains to be determined whether the drug improves mood or cognition in individuals with symptoms of depression.
Background: Despite increasing clinical and neuroscientific research, pharmacological neuroenhancement literature rarely discusses psychedelic drugs. However, psychedelic microdosing, the ingestion of sub-perceptual doses of psychedelics like psilocybin, has gained increasing public and scientific attention. Published research on the topic is scarce and systematic studies of the digital milieus surrounding psychedelic microdosing are currently non-existent. Methods: In this netnographic study, we explore psychedelic microdosing by focusing on Youtube™ and listing current research projects as a descriptive assemblage. We used the Youtube Data Tool (YDT) for data extraction from the YouTube™ platform. We selected videos that specifically focused on microdosing with a psychoactive substance and descriptively analysed the ecology of practices of the six most viewed videos focusing on definitions, dosages per substance and claimed effects. Results: Our initial data extraction, completed in 2016, resulted in total of 115 Youtube™ videos. Additional data extractions done in 2017 and 2018 showed a 290% increase of “microdosing” videos between 2016 and 2018, indicating that the phenomenon is growing, at least online. The digital milieu of microdosing in 2016 included 48 videos (41,7%) which mentioned a psychoactive substance. The six most viewed videos comprised 92% (N = 934,819) of the total view count and the ecology of practices depicted psychedelic microdosing as beneficial, but the claimed effects and dosing require critical evaluation. Contrary to how typical users of illicit drugs are often portrayed in the media and science, these videos revolved around themes like research, experiments, self-monitoring and the imperative of sharing results. As our descriptive assemblage demonstrates several psychedelic microdosing research projects are under way, potentially influencing user practices and knowledge. Conclusion: This type of online drug research can be used to gather knowledge of under-researched topics, like psychedelic microdosing. However, further digital and non-digital drug research is needed to investigate this potentially rising phenomenon.
Albert Hoffman suggested that low doses of LSD might be an appropriate alternative to Ritalin. Following this possibility, a systematic exploration of the effects of “microdoses,” comprising hundreds of lengthy descriptive reports, was undertaken. Based on these reports, using a psychedelic in the microdose range (10 micrograms) every three days was determined to be safe across a wide variety of individuals and conditions. Over 18 months, more than a thousand individuals from 59 countries did a daily evaluation of negative and positive emotional state using the PANAS checklist plus written reports for between one week and four months. Participant reports suggested that spaced but repeated microdoses were followed by improvements in negative moods, especially depression, and increases in positive moods. Increased energy, improved work effectiveness, and improved health habits were observed in clinical and non-clinical populations. Smaller samples described alleviation of symptoms in migraine headaches, pre-menstrual syndromes, traumatic brain injury, shingles, and other conditions not previously associated with psychedelic use.
The prototype 5-HT2A receptor agonist hallucinogens LSD, mescaline, and psilocybin are classified as Schedule 1 drugs of abuse by the U.S. Drug Enforcement Administration. Accumulating clinical evidence has also suggested that acute or repeated “microdosing” with these drugs may have utility for treatment of some mental health disorders, including drug abuse and depression. The goal of the present study was to evaluate LSD, mescaline, and psilocybin effects on intracranial self-stimulation (ICSS), a procedure that has been used to evaluate abuse-related effects of other classes of abused drugs. Effects of repeated LSD were also examined to evaluate potential changes in its own effects on ICSS or changes in effects produced by the abused psychostimulant methamphetamine or the prodepressant kappa opioid receptor (KOR) agonist U69,593. Male Sprague–Dawley rats were implanted with microelectrodes targeting the medial forebrain bundle and trained to respond under a “frequency-rate” ICSS procedure, in which many drugs of abuse increase (or “facilitate”) ICSS. In acute dose-effect and time-course studies, evidence for abuse-related ICSS facilitation was weak and inconsistent; the predominant effect of all 3 drugs was dose- and time-dependent ICSS depression. Repeated LSD treatment failed to alter either its own ICSS depressant effects or the abuse-related effects of methamphetamine; however, repeated LSD did attenuate ICSS depression by U69,593. These results extend those of previous preclinical studies to suggest weak expression of abuse-related effects by 5-HT2A agonist hallucinogens and provide supportive evidence for therapeutic effects of repeated LSD dosing to attenuate KOR-mediated depressant effects but not abuse potential of psychostimulants.
Serotonin (5-hydroxytryptamine, 5-HT)2A receptor agonists have recently emerged as promising new treatment options for a variety of disorders. The recent success of these agonists, also known as psychedelics, like psilocybin for the treatment of anxiety, depression, obsessive-compulsive disorder (OCD), and addiction, has ushered in a renaissance in the way these compounds are perceived in the medical community and populace at large. One emerging therapeutic area that holds significant promise is their use as anti-inflammatory agents. Activation of 5-HT2A receptors produces potent anti-inflammatory effects in animal models of human inflammatory disorders at sub-behavioural levels. This review discusses the role of the 5-HT2A receptor in the inflammatory response, as well as highlight studies using the 5-HT2A agonist (R)-2,5-dimethoxy-4-iodoamphetamine [(R)-DOI] to treat inflammation in cellular and animal models. It also examines potential mechanisms by which 5-HT2A agonists produce their therapeutic effects. Overall, psychedelics regulate inflammatory pathways via novel mechanisms, and may represent a new and exciting treatment strategy for several inflammatory disorders.
Recent studies suggest that the antidepressant effects of the psychedelic 5-HT2A receptor agonist psilocybin are mediated through its modulatory properties on prefrontal and limbic brain regions including the amygdala. To further investigate the effects of psilocybin on emotion processing networks, we studied for the first-time psilocybin's acute effects on amygdala seed-to-voxel connectivity in an event-related face discrimination task in 18 healthy volunteers who received psilocybin and placebo in a double-blind balanced cross-over design. The amygdala has been implicated as a salience detector especially involved in the immediate response to emotional face content. We used beta-series amygdala seed-to-voxel connectivity during an emotional face discrimination task to elucidate the connectivity pattern of the amygdala over the entire brain.
When we compared psilocybin to placebo, an increase in reaction time for all three categories of affective stimuli was found. Psilocybin decreased the connectivity between amygdala and the striatum during angry face discrimination. During happy face discrimination, the connectivity between the amygdala and the frontal pole was decreased. No effect was seen during discrimination of fearful faces. Thus, we show psilocybin's effect as a modulator of major connectivity hubs of the amygdala. Psilocybin decreases the connectivity between important nodes linked to emotion processing like the frontal pole or the striatum. Future studies are needed to clarify whether connectivity changes predict therapeutic effects in psychiatric patients.
Psychedelic drugs, such as lysergic acid diethylamide (LSD), mescaline, and psilocybin, exert profound effects on brain and behavior. After decades of difficulties in studying these compounds, psychedelics are again being tested as potential treatments for intractable biomedical disorders. Preclinical research of psychedelics complements human neuroimaging studies and pilot clinical trials, suggesting these compounds as promising treatments for addiction, depression, anxiety, and other conditions. However, many questions regarding the mechanisms of action, safety, and efficacy of psychedelics remain. Here, we summarize recent preclinical and clinical data in this field, discuss their pharmacological mechanisms of action, and outline critical areas for future studies of psychedelic drugs, with the goal of maximizing the potential benefits of translational psychedelic biomedicine to patients.
Today, there is continued, and in some cases growing, availability of not only psychoactive substances, including treatments for mental health disorders such as cognitive enhancers, which can enhance or restore brain function, but also ‘recreational’ drugs such as novel psychoactive substances (NPS). The use of psychoactive drugs has both benefits and risks: whilst new drugs to treat cognitive symptoms in neuropsychiatric or neurodegenerative disorders could have great benefits for many patient groups, the increasing ease of accessibility to recreational NPS and the increasing lifestyle use of cognitive enhancers by healthy people means that the effective management of psychoactive substances will be an issue of increasing importance. Clearly, the potential benefits of cognitive enhancers are large and increasingly relevant, particularly as the population ages, and for this reason, we should continue to devote resources to the development of cognitive enhancers as treatments for neurodegenerative diseases and psychiatric disorders, including Alzheimer's disease, attention deficit hyperactivity disorder and schizophrenia. However, the increasing use of cognitive enhancers by healthy individuals raises safety, ethical and regulatory concerns, which should not be ignored. Similarly, understanding the short‐ and long‐term consequences of the use of NPS, as well as better understanding the motivations and profiles of users could promote more effective prevention and harm reduction measures.
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This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc
The prototypical hallucinogen LSD acts via serotonin receptors, and here we describe the crystal structure of LSD in complex with the human serotonin receptor 5-HT2B. The complex reveals conformational rearrangements to accommodate LSD, providing a structural explanation for the conformational selectivity of LSD’s key diethylamide moiety. LSD dissociates exceptionally slow from both 5-HT2BR and 5-HT2AR—a major target for its psychoactivity. Molecular dynamics (MD) simulations suggest that LSD’s slow binding kinetics may be due to a “lid” formed by extracellular loop 2 (EL2) at the entrance to the binding pocket. A mutation predicted to increase the mobility of this lid greatly accelerates LSD’s binding kinetics and selectively dampens LSD-mediated β-arrestin2 recruitment. This study thus reveals an unexpected binding mode of LSD; illuminates key features of its kinetics, stereochemistry, and signaling; and provides a molecular explanation for LSD’s actions at human serotonin receptors.
An extensive body of research suggests the spontaneous eye blink rate (EBR) is a non-invasive indirect marker of central dopamine (DA) function, with higher EBR predicting higher DA function. In the present review we provide a comprehensive overview of this literature. We broadly divide the available research in studies that aim to disentangle the dopaminergic underpinnings of EBR, investigate its utility in diagnosis of DA-related disorders and responsivity to drug treatment, and, lastly, investigate EBR as predictor of individual differences in DA-related cognitive performance. We conclude (i) EBR can reflect both DA receptor subtype D1 and D2 activity, although baseline EBR might be most strongly related to the latter, (ii) EBR can predict hypo- and hyperdopaminergic activity as well as normalization of this activity following treatment, and (iii) EBR can reliably predict individual differences in performance on many cognitive tasks, in particular those related to reward-driven behavior and cognitive flexibility. In sum, this review establishes EBR as a useful predictor of DA in a wide variety of contexts.
Background:
A recent open-label pilot study (N = 15) found that two to three moderate to high doses (20 and 30 mg/70 kg) of the serotonin 2A receptor agonist, psilocybin, in combination with cognitive behavioral therapy (CBT) for smoking cessation, resulted in substantially higher 6-month smoking abstinence rates than are typically observed with other medications or CBT alone.
Objectives:
To assess long-term effects of a psilocybin-facilitated smoking cessation program at ≥12 months after psilocybin administration.
Methods:
The present report describes biologically verified smoking abstinence outcomes of the previous pilot study at ≥12 months, and related data on subjective effects of psilocybin.
Results:
All 15 participants completed a 12-month follow-up, and 12 (80%) returned for a long-term (≥16 months) follow-up, with a mean interval of 30 months (range = 16-57 months) between target-quit date (i.e., first psilocybin session) and long-term follow-up. At 12-month follow-up, 10 participants (67%) were confirmed as smoking abstinent. At long-term follow-up, nine participants (60%) were confirmed as smoking abstinent. At 12-month follow-up 13 participants (86.7%) rated their psilocybin experiences among the five most personally meaningful and spiritually significant experiences of their lives.
Conclusion:
These results suggest that in the context of a structured treatment program, psilocybin holds considerable promise in promoting long-term smoking abstinence. The present study adds to recent and historical evidence suggesting high success rates when using classic psychedelics in the treatment of addiction. Further research investigating psilocybin-facilitated treatment of substance use disorders is warranted.
N,N-Dimethyltryptamine (DMT) is an indole alkaloid widely found in plants and animals. It is best known for producing brief and intense psychedelic effects when ingested. Increasing evidence suggests that endogenous DMT plays important roles for a number of processes in the periphery and central nervous system, and may act as a neurotransmitter. This paper reviews the current literature of both the recreational use of DMT and its potential roles as an endogenous neurotransmitter. Pharmacokinetics, mechanisms of action in the periphery and central nervous system, clinical uses and adverse effects are also reviewed. DMT appears to have limited neurotoxicity and other adverse effects except for intense cardiovascular effects when administered intravenously in large doses. Because of its role in nervous system signaling, DMT may be a useful experimental tool in exploring how brain works, and may also be a useful clinical tool for treatment of anxiety and psychosis.
Expectancy effects are a widespread phenomenon, and they come with a lasting influence on cognitive operations, from basic stimulus processing to higher cognitive functions. Their impact is often profound and behaviorally significant, as evidenced by an enormous body of literature investigating the characteristics and possible processes underlying expectancy effects. The literature on this topic spans diverse fields, from clinical psychology to cognitive neuroscience, and from social psychology to behavioral biology. We present an emerging perspective on these diverse phenomena and show how this perspective stimulates new toeholds for investigation, provides insight in underlying mechanisms, improves awareness of methodological confounds, and can lead to a deeper understanding of the effects of expectations on a broad spectrum of cognitive processes.
Traditional approaches to action control assume the existence of a more or less unitary control system that struggles with, and serves to overcome action tendencies induced by automatic processes. In this article, I point out that and why these approaches fail to capture the complexity and dynamics of cognitive control. I describe an alternative approach that assumes that control emerges from the interaction of at least two counteracting forces: one system promoting persistence and the maintenance of action goals and another promoting mental and behavioral flexibility. I describe how this interaction might be shaped by various factors, including genetic predisposition, learning, personal experience, and the cultural context, and suggest a simple functional model (the Metacontrol State Model, MSM) that explains how this shaping process works. Then I provide an overview of studies from various fields (including perception, attention, performance monitoring, conflict resolution, creativity, meditation, religion, and interpersonal perception and behavior) that successfully tested predictions from the MSM.
The mixed serotonin (5-HT) 1A/2A/2B/2C/6/7 receptor agonist psilocybin dose-dependently induces an altered state of consciousness (ASC) that is characterized by changes in sensory perception, mood, thought, and the sense of self. The psychological effects of psilocybin are primarily mediated by 5-HT2A receptor activation. However, accumulating evidence suggests that 5-HT1A or an interaction between 5-HT1A and 5-HT2A receptors may contribute to the overall effects of psilocybin. Therefore, we used a double-blind, counterbalanced, within-subject design to investigate the modulatory effects of the partial 5-HT1A agonist buspirone (20 mg p.o.) and the non-hallucinogenic 5-HT2A/1A agonist ergotamine (3 mg p.o.) on psilocybin-induced (170 µg/kg p.o.) psychological effects in two groups (n=19, n=17) of healthy human subjects. Psychological effects were assessed using the Altered State of Consciousness (5D-ASC) rating scale. Buspirone significantly reduced the 5D-ASC main scale score for Visionary Restructuralization (VR) (p<0.001), which was mostly driven by a reduction of the VR item cluster scores for elementary and complex visual hallucinations. Further, buspirone also reduced the main scale score for Oceanic Boundlessness including derealisation and depersonalisation phenomena at a trend level (p=0.062), whereas ergotamine did not show any effects on the psilocybin-induced 5D-ASC main scale scores. The present finding demonstrates that buspirone exerts inhibitory effects on psilocybin-induced effects, presumably via 5-HT1A receptor activation, an interaction between 5-HT1A and 5-HT2A receptors, or both. The data suggest that the modulation of 5-HT1A receptor activity may be a useful target in the treatment of visual hallucinations in different psychiatric and neurological diseases.