OPEN Foundation

Author name: OPEN Foundation

A qualitative descriptive analysis of effects of psychedelic phenethylamines and tryptamine

Abstract

OBJECTIVE:

The number of novel psychedelic phenethylamines and tryptamines has continued to increase, but little academic research has focused on the effects of these substances. We sought to determine and compare the subjective effects of various substances.

METHODS:

We conducted in-depth interviews with 39 adults (75.4% male and 87.2% White) who reported experience using psychedelic phenethylamines and/or tryptamines. Participants described the effects of compounds they have used. We examined the subjective drug effects in a qualitative descriptive manner.

RESULTS:

Participants reported on the use of 36 compounds. The majority (64.1%) reported the use of 2C series drugs, with 2C-B use being most prevalent; 38.5% reported the use of NBOMe, and 25.6% reported the use of DOx. With regard to tryptamines, 46.2% reported use, and 4-AcO-DMT was the most prevalent drug used in this class. 2C-B was often described as being more favorable than other 2C series compounds with the effects described as being comparable with MDMA and LSD. NBOMe effects were generally described in an unfavorable manner, and the effects of DOx were often described as lasting too long (12-36 hr). The effects of 4-AcO-DMT were often described as mimicking psilocybin.

CONCLUSION:

Knowing the effects of various compounds can inform education, prevention, and harm reduction efforts regarding the use of these drugs.

Palamar, J. J., & Acosta, P. (2020). A qualitative descriptive analysis of effects of psychedelic phenethylamines and tryptamines. Human Psychopharmacology: Clinical and Experimental, e2719., 10.1002/hup.2719
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Correlation between the potency of hallucinogens in the mouse head-twitch response assay and their behavioral and subjective effects in other species

Abstract

Serotonergic hallucinogens such as lysergic acid diethylamide (LSD) induce head twitches in rodents via 5-HT2A receptor activation. The goal of the present investigation was to determine whether a correlation exists between the potency of hallucinogens in the mouse head-twitch response (HTR) paradigm and their reported potencies in other species, specifically rats and humans. Dose-response experiments were conducted with phenylalkylamine and tryptamine hallucinogens in C57BL/6J mice, enlarging the available pool of HTR potency data to 41 total compounds. For agents where human data are available (n = 36), a strong positive correlation (r = 0.9448) was found between HTR potencies in mice and reported hallucinogenic potencies in humans. HTR potencies were also found to be correlated with published drug discrimination ED50 values for substitution in rats trained with either LSD (r = 0.9484, n = 16) or 2,5-dimethoxy-4-methylamphetamine (r = 0.9564, n = 21). All three of these behavioral effects (HTR in mice, hallucinogen discriminative stimulus effects in rats, and psychedelic effects in humans) have been linked to 5-HT2A receptor activation. We present evidence that hallucinogens induce these three effects with remarkably consistent potencies. In addition to having high construct validity, the HTR assay also appears to show significant predictive validity, confirming its translational relevance for predicting subjective potency of hallucinogens in humans. These findings support the use of the HTR paradigm as a preclinical model of hallucinogen psychopharmacology and in structure-activity relationship studies of hallucinogens. Future investigations with a larger number of test agents will evaluate whether the HTR assay can be used to predict the hallucinogenic potency of 5-HT2A agonists in humans.

Halberstadt, A. L., Chatha, M., Klein, A. K., Wallach, J., & Brandt, S. D. (2020). Correlation between the potency of hallucinogens in the mouse head-twitch response assay and their behavioral and subjective effects in other species. Neuropharmacology, 107933., 10.1016/j.neuropharm.2019.107933
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The experimental effects of psilocybin on symptoms of anxiety and depression: A meta-analysis.

Abstract

The current meta-analysis examined the effects of psilocybin in combination with behavioral interventions on anxiety and depression in samples with elevated symptoms. Across four studies (one uncontrolled; three randomized, placebo-controlled; N = 117), within-group pre-post and pre-follow-up effects on anxiety and depression were large (Hedges’ gs=1.16 to 1.47) and statistically significant. Across three placebo-controlled studies, pre-post placebo-controlled effects were also large (gs = 0.82 to 0.83) and statistically significant. No serious adverse events were reported. Limitations include the small number of studies and risk for bias within studies. Results tentatively support future research on psilocybin for the treatment of anxiety and depression.

Goldberg, S. B., Pace, B. T., Nicholas, C. R., Raison, C. L., & Hutson, P. R. (2020). The experimental effects of psilocybin on symptoms of anxiety and depression: A meta-analysis. Psychiatry Research, 112749., https://doi.org/10.1016/j.psychres.2020.112749
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[Neuroscientific and psychological explanations for the therapeutic effects of psychedelics]

Abstract

Psychedelics have a strong therapeutic potential for the treatment of biomedical disorders, but the working mechanisms underlying psychedelics are only poorly understood.<br/> AIM: To discuss different mechanisms underlying the therapeutic effects of classic psychedelics.<br/> METHOD: To make a distinction between different levels of explanation: the pharmacological, the neurocognitive and the psychological level.<br/> RESULTS: At the pharmacological level, classic psychedelics affect via the serotonin-receptor, the production of glutamate and brain-derived neurotrophic factor (bdnf), which stimulate neurogenesis. Psychedelics also have anti-flammatory properties and thereby have a protective effect on the brain. At the neurocognitive level, psychedelics have been associated with a reduced activation of the default mode network, which has been implicated in self-referential processing and rumination. At the same time, the brain’s entropy increases, reflected in an increased connectivity between different brain areas. At the psychological level, the therapeutic efficacy of psychedelics has been attributed to the mystical experience, as well as to its awe-inducing potential, the feelings of connectedness and an enhanced awareness of emotions.<br/> CONCLUSION: Psycholytic and psychedelic therapy act at different levels, but ultimately the combination of different mechanisms will help us to understand how psychedelics – in the right set and setting – can be used successfully in therapeutic practice.
van Elk, M. (2020). Neuroscientific and psychological explanations for the therapeutic effects of psychedelics. Tijdschrift Voor Psychiatrie62(8), 677-683., https://pubmed.ncbi.nlm.nih.gov/32816296/
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Preliminary Report on the Effects of a Low Dose of LSD on Resting-State Amygdala Functional Connectivity.

Abstract

BACKGROUND:
The practice of “microdosing,” or the use of repeated, very low doses of lysergic acid diethylamide (LSD) to improve mood or cognition, has received considerable public attention, but empirical studies are lacking. Controlled studies are needed to investigate both the therapeutic potential and the neurobiological underpinnings of this pharmacologic treatment.
METHODS:
The present study was designed to examine the effects of a single low dose of LSD (13 μg) versus placebo on resting-state functional connectivity and cerebral blood flow in healthy young adults. Twenty men and women, 18 to 35 years old, participated in 2 functional magnetic resonance imaging scanning sessions in which they received placebo or LSD under double-blind conditions. During each session, the participants completed drug effect and mood questionnaires, and physiological measures were recorded. During expected peak drug effect, they underwent resting-state blood oxygen level-dependent and arterial spin labeling scans. Cerebral blood flow as well as amygdala and thalamic connectivity were analyzed.
RESULTS:
LSD increased amygdala seed-based connectivity with the right angular gyrus, right middle frontal gyrus, and the cerebellum, and decreased amygdala connectivity with the left and right postcentral gyrus and the superior temporal gyrus. This low dose of LSD had weak and variable effects on mood, but its effects on positive mood were positively correlated with the increase in amygdala-middle frontal gyrus connectivity strength.
CONCLUSIONS:
These preliminary findings show that a very low dose of LSD, which produces negligible subjective changes, alters brain connectivity in limbic circuits. Additional studies, especially with repeated dosing, will reveal whether these neural changes are related to the drug’s purported antidepressant effect.

Bershad, A. K., Preller, K. H., Lee, R., Keedy, S., Wren-Jarvis, J., Bremmer, M. P., & de Wit, H. (2019). Preliminary report on the effects of a low dose of LSD on resting state amygdalar functional connectivity. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging., https://doi.org/10.1016/j.bpsc.2019.12.007
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Safety, tolerability, pharmacokinetics, and pharmacodynamics of low dose lysergic acid diethylamide (LSD) in healthy older volunteers.

Abstract

Research has shown that psychedelics, such as lysergic acid diethylamide (LSD), have profound anti-inflammatory properties mediated by 5-HT2A receptor signaling, supporting their evaluation as a therapeutic for neuroinflammation associated with neurodegenerative disease.
OBJECTIVE:
This study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of orally repeated administration of 5 μg, 10 μg, and 20 μg LSD in older healthy individuals. In the current paper, we present safety, tolerability, pharmacokinetics, and pharmacodynamic measures that relate to safety, tolerability, and dose response.
METHODS:
This was a phase 1 double-blind, placebo-controlled, randomized study. Volunteers were randomly assigned to 1 of 4 dose groups (5 μg, 10 μg, 20 μg LSD, and placebo), and received their assigned dose on six occasions (i.e., every 4 days).
RESULTS:
Forty-eight older healthy volunteers (mean age = 62.9 years) received placebo (n = 12), 5 μg (n = 12), 10 μg (n = 12), or 20 μg (n = 12) LSD. LSD plasma levels were undetectable for the 5 μg group and peak blood plasma levels for the 10 μg and 20 μg groups occurred at 30 min. LSD was well tolerated, and the frequency of adverse events was no higher than for placebo. Assessments of cognition, balance, and proprioception revealed no impairment.
CONCLUSIONS:
Our results suggest safety and tolerability of orally administered 5 μg, 10 μg, and 20 μg LSD every fourth day over a 21-day period and support further clinical development of LSD for the treatment and prevention of Alzheimer’s disease (AD).
Family, N., Maillet, E. L., Williams, L. T., Krediet, E., Carhart-Harris, R. L., Williams, T. M., … & Raz, S. (2019). Safety, tolerability, pharmacokinetics, and pharmacodynamics of low dose lysergic acid diethylamide (LSD) in healthy older volunteers. Psychopharmacology, 1-13., https://doi.org/10.1007/s00213-019-05417-7
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Safety, tolerability, pharmacokinetics, and pharmacodynamics of low dose lysergic acid diethylamide (LSD) in healthy older volunteers. Read More »

Decreased directed functional connectivity in the psychedelic state.

Abstract

Neuroimaging studies of the psychedelic state offer a unique window onto the neural basis of conscious perception and selfhood. Despite well understood pharmacological mechanisms of action, the large-scale changes in neural dynamics induced by psychedelic compounds remain poorly understood. Using source-localised, steady-state MEG recordings, we describe changes in functional connectivity following the controlled administration of LSD, psilocybin and low-dose ketamine, as well as, for comparison, the (non-psychedelic) anticonvulsant drug tiagabine. We compare both undirected and directed measures of functional connectivity between placebo and drug conditions. We observe a general decrease in directed functional connectivity for all three psychedelics, as measured by Granger causality, throughout the brain. These data support the view that the psychedelic state involves a breakdown in patterns of functional organisation or information flow in the brain. In the case of LSD, the decrease in directed functional connectivity is coupled with an increase in undirected functional connectivity, which we measure using correlation and coherence. This surprising opposite movement of directed and undirected measures is of more general interest for functional connectivity analyses, which we interpret using analytical modelling. Overall, our results uncover the neural dynamics of information flow in the psychedelic state, and highlight the importance of comparing multiple measures of functional connectivity when analysing time-resolved neuroimaging data.

Barnett, L., Muthukumaraswamy, S. D., Carhart-Harris, R. L., & Seth, A. K. (2019). Decreased directed functional connectivity in the psychedelic state. NeuroImage, 116462., https://doi.org/10.1016/j.neuroimage.2019.116462
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From Egoism to Ecoism: Psychedelics Increase Nature Relatedness in a State-Mediated and Context-Dependent Manner.

Abstract

(1) Background: There appears to be a growing disconnection between humans and their natural environments which has been linked to poor mental health and ecological destruction. Previous research suggests that individual levels of nature relatedness can be increased through the use of classical psychedelic compounds, although a causal link between psychedelic use and nature relatedness has not yet been established. (2) Methods: Using correlations and generalized linear mixed regression modelling, we investigated the association between psychedelic use and nature relatedness in a prospective online study. Individuals planning to use a psychedelic received questionnaires 1 week before (N = 654), plus one day, 2 weeks, 4 weeks, and 2 years after a psychedelic experience. (3) Results: The frequency of lifetime psychedelic use was positively correlated with nature relatedness at baseline. Nature relatedness was significantly increased 2 weeks, 4 weeks and 2 years after the psychedelic experience. This increase was positively correlated with concomitant increases in psychological well-being and was dependent on the extent of ego-dissolution and the perceived influence of natural surroundings during the acute psychedelic state. (4) Conclusions: The here presented evidence for a context- and state-dependent causal effect of psychedelic use on nature relatedness bears relevance for psychedelic treatment models in mental health and, in the face of the current ecological crisis, planetary health.
Kettner, H., Gandy, S., Haijen, E. C., & Carhart-Harris, R. L. (2019). From Egoism to Ecoism: Psychedelics Increase Nature Relatedness in a State-Mediated and Context-Dependent Manner. International Journal of Environmental Research and Public Health16(24), 5147., https://doi.org/10.3390/ijerph16245147
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From Egoism to Ecoism: Psychedelics Increase Nature Relatedness in a State-Mediated and Context-Dependent Manner. Read More »

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