Classical hallucinogens and neuroimaging: A systematic review of human studies

Santos, Rafael G. dos; Osório, Flávia de Lima; Crippa, José Alexandre de Souza; Hallak, Jaime Eduardo Cecílio

doi:10.1016/j.neubiorev.2016.10.026

Cited by 92 publications

(104 citation statements)

References 88 publications

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“…photon emission computed tomography (SPECT), and structural and functional magnetic resonance imaging (MRI and fMRI, respectively). 21,25,26 Results from EEG studies are inconsistent and sometimes conflicting (Table 2) 26 . For instance, although reduced power in the alpha, delta and theta bands was observed in some studies 14,[27][28][29] , it was not reported in others 19,24 .…”

Section: Botany Chemistry and Mechanism Of Actionmentioning

confidence: 99%

“…In the last 10 years, the neural basis of the effects of ayahuasca have been investigated using SPECT, MRI and fMRI (Table 2) 21,25,26 . A SPECT study of acute administration with healthy volunteers showed that ayahuasca increased bilateral activation of the anterior insula/inferior frontal gyrus, right hemisphere activation of the anterior cingulate cortex (ACC) and frontomedial cortex, and left hemisphere activation of the amygdala and parahippocampal gyrus 32 .…”

Section: Botany Chemistry and Mechanism Of Actionmentioning

confidence: 99%

“…Furthermore, ayahuasca decreased functional connectivity within the PCC/precuneus. Studies with psilocybin and LSD also show that these drugs produce their effects by modulating brain structures involved in emotional processing and in memory and self-awareness, such as the parahippocampal gyrus, visual and frontal cortices, ACC and PCC, insula and amygdala 15,21,25,26,30,31 .…”

Section: Neurophysiological and Neuroimaging Studiesmentioning

confidence: 99%

“…Thus, it is not always possible to translate a therapeutic effect described in a traditional context to the concepts of diseases that are shared in the nonindigenous culture. However, over the last 30 years, an increasing number of anecdotal reports and experimental evidence has accumulated suggesting that ayahuasca may have therapeutic potentials in the treatment of difficult-to-treat psychiatric disorders such as drug dependence and anxiety and mood disorders 21,25,36 .…”

Section: Therapeutic Potentialsmentioning

confidence: 99%

“…Classic or serotonergic hallucinogens including LSD, psilocybin, mescaline and DMT are considered drugs with low physiological toxicity that can be safely administered in controlled settings, including both ritual and experimental/clinical contexts 8,17,25,26,36,52,53 . Recent human studies involving acute administration of LSD and psilocybin to healthy volunteers and to patients with drug dependence or anxiety and mood disorders show that these drugs induce significant subjective and physiological effects that are transient, well tolerated, and apparently associated with therapeutic effects 13,15,30,31,44,47,50,51,53 .…”

Section: Safety and Toxicitymentioning

confidence: 99%

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Ayahuasca: what mental health professionals need to know

Santos

Bouso²,

Hallak

2017

Arch. Clin. Psychiatry (São Paulo)

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Background: Ayahuasca is a psychoactive ethnobotanical concoction that has been used for decades by indigenous groups of the Northwestern Amazon and by syncretic religious organizations for ritual and therapeutic purposes. In the last two decades, it is being used worldwide in evolving practices. Ayahuasca seem to therapeutic effects, but controlled studies are lacking. Moreover, its safety and toxicity are not completely understood. Objectives: To present an overview of the effects of ayahuasca based on the most recent human studies. Methods: Narrative review. Results: Ayahuasca administration in controlled settings appears to be safe from a subjective and physiological perspective, with few adverse reactions being reported. More frequent adverse reactions occur in non-controlled settings. Prolonged psychotic reactions are rare and seem to occur especially in susceptible individuals. Ayahuasca showed antidepressive, anxiolytic, and antiaddictive effects in animal models, observational studies, and in open-label and controlled studies. Discussion: Ayahuasca administration in controlled settings appear to be safe. Moreover, ayahuasca seem to have therapeutic effects for treatment-resistant psychiatric disorders that should be further investigated in randomized controlled clinical trials. However, medical complications and cases of prolonged psychotic reactions have been reported, and people with personal or family history of psychotic disorders should avoid ayahuasca intake.

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Section: Botany Chemistry and Mechanism Of Actionmentioning

confidence: 99%

Section: Botany Chemistry and Mechanism Of Actionmentioning

confidence: 99%

Section: Neurophysiological and Neuroimaging Studiesmentioning

confidence: 99%

Section: Therapeutic Potentialsmentioning

confidence: 99%

Section: Safety and Toxicitymentioning

confidence: 99%

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Ayahuasca: what mental health professionals need to know

Santos

Bouso²,

Hallak

2017

Arch. Clin. Psychiatry (São Paulo)

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Hallucinogenic Drugs

Bonson¹

2020

Encyclopedia of Life Sciences

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Hallucinogens constitute one of the oldest classes of drugs used by humanity, often in the context of spiritual practices. Classic hallucinogens such as lysergic acid diethylamide (LSD), psilocybin, N , N ‐dimethyltryptamine (DMT), mescaline and 2,5‐dimethoxy‐4‐methylamphetamine (DOM) produce complex psychological and physical effects, including perceptual changes, cognitive shifts in reality, and emotional alterations. These drugs primarily act on serotonin systems through 5‐hydroxytryptamine 2A (5HT 2A ) receptors, with additional activity through 5HT 1A receptors, as well as dopamine and glutamate systems. Investigations into the neurochemical and behavioural effects of this class of drugs have provided important insights into pharmacology and psychiatric conditions. Given their popularity as recreational drugs, investigation of their actions and effects continues to be an important endeavour. In the past 30 years, there has been a renewed interest in conducting clinical studies with these drugs in healthy individuals and in patients with psychiatric conditions in laboratories around the world. Key Concepts Hallucinogens have been used for thousands of years by various societies, often in conjunction with spiritual practices. In the present day, hallucinogens remain highly popular as recreational drugs. The chemical structure of hallucinogens consists of tryptamines (LSD and psilocybin) and phenethylamines (mescaline and DOM). The potency of hallucinogens is directly correlated to their ability to act as agonists at the serotonin receptor subtype, 5‐HT 2A . Drugs that act at sites other than 5‐HT 2A receptors can also produce hallucinogen‐like effects (e.g. ketamine, MDMA, salvinorin A, nitrous oxide, GHB). The signature effects of hallucinogens include perceptual changes, alterations in effect and shifts in cognitive ability. Negative responses associated with hallucinogens include ‘bad trips’ (severe anxiety and a disconnection with reality) as well as rare instances of ‘flashbacks’ and psychotic breaks. Human research with hallucinogens has recently been revitalised, augmenting the scientific advances made previously with animal and human studies.

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Effects of ayahuasca on the endocannabinoid system of healthy volunteers and in volunteers with social anxiety disorder: Results from two pilot, proof‐of‐concept, randomized, placebo‐controlled trials

Santos

Rocha

Rossi

et al. 2022

Human Psychopharmacology

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Objective: To assess endocannabinoid (anandamide, AEA; 2-arachidonoylglycerol, 2-AG) plasma levels in healthy volunteers and in volunteers with social anxiety disorder (SAD) after a single oral dose of ayahuasca or placebo. Methods:Post hoc analysis of endocannabinoid plasma levels (baseline, 90 and 240 min after drug intake) from two parallel-group, randomized, placebo-controlled trials. In Study 1, 20 healthy volunteers ingested ayahuasca (average 1.58 mg/ml dimethyltryptamine (DMT)) or placebo, and in Study 2, 17 volunteers with SAD received ayahuasca (average 0.680 mg/ml DMT) or placebo.Results: A significant difference was observed in AEA concentrations in Study 2 after ayahuasca intake (Χ 2 (2) = 6.5, p = 0.03, Friedman test), and near significant differences (increases) were observed between baseline and 90 (Z = 0, p = 0.06, Wilcoxon test) and 240 (Z = 10, p = 0.06) minutes after ayahuasca intake. Conclusions:Although our findings suggest that ayahuasca could modulate AEA levels in SAD patients, the high interindividual variability in both trials and the small samples preclude definitive conclusions. More research with larger samples is needed to better understand the effects of ayahuasca and other hallucinogens in the endocannabinoid system.

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Classical hallucinogens and neuroimaging: A systematic review of human studies

Cited by 92 publications

References 88 publications

Ayahuasca: what mental health professionals need to know

Ayahuasca: what mental health professionals need to know

Hallucinogenic Drugs

Effects of ayahuasca on the endocannabinoid system of healthy volunteers and in volunteers with social anxiety disorder: Results from two pilot, proof‐of‐concept, randomized, placebo‐controlled trials

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