Interactive Effects of Ayahuasca and Cannabidiol in Social Cognition in Healthy Volunteers: A Pilot, Proof-of-Concept, Feasibility, Randomized-Controlled Trial

Long-term ayahuasca use is associated with preserved global cognitive function and improved memory: a cross-sectional study with ritual users

Although several studies have been conducted to elucidate the relationship between psychedelic consumption and cognition, few have focused on understanding the long-term use influence of these substances on these variables, especially in ritualistic contexts.  To verify the influence of ritualistic ayahuasca consumption on the cognition of experienced ayahuasca religious users (> 20 years) and beginners (< 3 years), which participated in rituals of the Centro Luz Divina (CLD), a Santo Daime church in Brazil. Observational, descriptive, and cross-sectional study was carried out in which 48 people participated divided into three groups: (a) experienced ayahuasca users (n = 16), (b) beginner ayahuasca users (n = 16) and (c) control group (n = 16). All groups were matched by sex, age, and education and contained 8 women and 8 men. Cognition was assessed with the WASI (intelligence quotient), Digit Span (verbal working memory), Corsi Block-Tapping Task (visuospatial-related and working memory), Rey-Osterrieth Complex Figure test (visual perception, immediate memory), and Wisconsin Card Sorting and Five Digit Test (executive functions). Groups were homogenous in terms of sociodemographic characteristics, with participants presenting average intellectual performance. There was no evidence of cognitive decline amongst ayahuasca users. The experienced group showed higher scores compared to the less experienced group in the Digit Span and Corsi Block-Tapping tasks, which assess working verbal and visuospatial memories respectively. We confirmed the botanical identities of Psychotria viridis and Banisteriopsis caapi and the presence of the alkaloids both in the plants and in the brew. Short and long-term ayahuasca consumption does not seem to alter human cognition, while long-term use seems to be associated with improvements in aspects of working memory when compared with short-term use.

Ayahuasca: pharmacology, safety, and therapeutic effects

Ayahuasca is a botanical hallucinogen traditionally used for therapeutic and ritual purposes by indigenous groups from Northwestern Amazonian countries such as Brazil, Peru, Colombia, and Ecuador. Ayahuasca is made by the decoction of two plants, which are rich in the 5-HT1A/2A partial agonist dimethyltryptamine or DMT (from the leaves of the Psychotria viridis bush) and β-carbolines such as harmine, from the stalks of the Banisteriopsis caapi vine. There is an increasing interest in the possible therapeutic effects of ayahuasca, especially for psychiatric disorders (major depression, posttraumatic stress disorder, and substance use disorder). This review summarizes information on the pharmacology, safety, and therapeutic potentials of ayahuasca. Although human experimental and naturalist studies published until now suggest a good safety and tolerability profile, often associated with improvements in depressive and anxious symptoms, there are few controlled studies, with small sample sizes, using only single doses, and with short follow-ups. Potential benefits of ayahuasca should be evaluated in larger samples in both experimental and observational studies and using different doses in controlled trials.

A Phase 1 single ascending dose study of pure oral harmine in healthy volunteers

BACKGROUND

Harmine is a component of the hallucinogenic brew, Ayahuasca, which also contains the psychoactive compound, N, N-dimethyltryptamine. Whether pharmaceutical-grade harmine hydrochloride (HCl) has psychoactive effects, the doses at which these might occur, and the dose-response relationship to side effects and safety in humans are unknown.

METHODS

We conducted a Phase 1, open-label single ascending dose trial in healthy adults with normal body mass index and no prior psychiatric illness. The primary goal was to determine the maximum tolerated dose (MTD) of oral pharmaceutical-grade harmine HCl and to characterize safety and tolerability. A secondary goal was to ascertain whether any oral dose has psychoactive effects.

RESULTS

Thirty-four adult participants, aged 18-55 years, were screened for study eligibility. Twenty-five participants met eligibility criteria and were randomized to a single dose of 100, 200, 300, or 500 mg of harmine HCl, respectively, using a continuous reassessment method. The most common adverse events (AEs) observed were gastrointestinal and/or neurological, dose-related, and of mild to moderate severity. The MTD was determined to be between 100 and 200 mg and is weight-based, with 90% of those participants receiving >2.7 mg/kg experiencing a dose-limiting toxicity. No serious AEs of harmine HCl were identified.

CONCLUSIONS

Harmine HCl can be orally administered to healthy participants in doses <2.7 mg/kg with minimal or no AEs. Doses >2.7 mg/kg are associated with vomiting, drowsiness, and limited psychoactivity. This study is the first to systematically characterize the psychoactive effects of pharmaceutical quality harmine in healthy participants.

Effects of a Single Dose of Ayahuasca in College Students With Harmful Alcohol Use: A Single-blind, Feasibility, Proof-of-Concept Trial

BACKGROUND

Ayahuasca is a South American plant hallucinogen rich in the psychedelic N,N-dimethyltryptamine and β-carbolines (mainly harmine). Preclinical and observational studies suggest that ayahuasca exerts beneficial effects in substance use disorders, but these potentials were never assessed in a clinical trial.

METHODS

Single-center, single-blind, feasibility, proof-of-concept study, assessing the effects of one dose of ayahuasca accompanied by psychological support (without psychotherapy) on the drinking patterns (primary variable) of 11 college students with harmful alcohol consumption. Secondary variables included safety and tolerability, craving, personality, anxiety, impulsivity, self-esteem, and social cognition.

FINDINGS

Ayahuasca was well tolerated (no serious adverse reactions were observed), while producing significant psychoactive effects. Significant reductions in days per week of alcohol consumption were found between weeks 2 and 3 (2.90 ± 0.28 vs 2.09 ± 0.41; P < 0.05, uncorrected), which were not statistically significant after Bonferroni correction. There were no statistically significant effects for other variables, except for a significant reduction in reaction time in an empathy task.

CONCLUSIONS

A significant reduction in days of alcohol consumption was observed 2-3 weeks after ayahuasca intake, but this effect did not survive after Bonferroni correction. The lack of significant effects in alcohol use and other variables may be related to the small sample size and mild/moderate alcohol use at baseline. The present study shows the feasibility of our protocol, paving the way for future larger, controlled studies.

Cannabidiol and its Potential Evidence-Based Psychiatric Benefits - A Critical Review

The endocannabinoid system shows promise as a novel target for treating psychiatric conditions. Cannabidiol (CBD), a naturally occurring cannabinoid, has been investigated in several psychiatric conditions, with diverse effects and an excellent safety profile compared to standard treatments. Even though the body of evidence from randomised clinical trials is growing, it remains relatively limited in most indications. This review comprises a comprehensive literature search to identify clinical studies on the effects of CBD in psychiatric conditions. The literature search included case studies, case reports, observational studies, and RCTs published in English before July 27, 2023, excluding studies involving nabiximols or cannabis extracts containing CBD and ∆9-tetrahydrocannabinol. Completed studies were considered, and all authors independently assessed relevant publications.Of the 150 articles identified, 54 publications were included, covering the effects of CBD on healthy subjects and various psychiatric conditions, such as schizophrenia, substance use disorders (SUDs), anxiety, post-traumatic stress disorder (PTSD), and autism spectrum disorders. No clinical studies have been published for other potential indications, such as alcohol use disorder, borderline personality disorder, depression, dementia, and attention-deficit/hyperactivity disorder. This critical review highlights that CBD can potentially ameliorate certain psychiatric conditions, including schizophrenia, SUDs, and PTSD. However, more controlled studies and clinical trials, particularly investigating the mid- to long-term use of CBD, are required to conclusively establish its efficacy and safety in treating these conditions. The complex effects of CBD on neural activity patterns, likely by impacting the endocannabinoid system, warrant further research to reveal its therapeutic potential in psychiatry.

Formulated Palmitoylethanolamide Supplementation Improves Parameters of Cognitive Function and BDNF Levels in Young, Healthy Adults: A Randomised Cross-Over Trial

BACKGROUND

Palmitoylethanolamide (PEA) is an endocannabinoid-like lipid mediator which is naturally produced in the body and found in certain foods. The aim of this study was to assess the effect of a bioavailable formulated form of PEA (Levagen+®) on serum BDNF levels and parameters of cognitive function in healthy adults.

METHODS

A randomised double-blinded placebo-controlled cross-over trial was implemented to measure the effects of a 6-week 700 mg/day course of formulated PEA supplementation versus a placebo. Participants (n = 39) completed pre- and post-assessments of a lab-based cognitive test. Serum samples were collected to measure BDNF concentrations using an immunoassay.

RESULTS

A significant increase in serum BDNF levels was found following PEA supplementation compared with the placebo (p = 0. 0057, d = 0.62). The cognition test battery demonstrated improved memory with PEA supplementation through better first success (p = 0.142, d = 0.54) and fewer errors (p = 0.0287; d = -0.47) on the Paired Associates Learning test.

CONCLUSION

This was the first study to report a direct beneficial effect of Levagen+® PEA supplementation on memory improvement as well as corresponding increases in circulating neurotrophic marker levels. This suggests that formulated PEA holds promise as an innovative and practical intervention for cognitive health enhancement.