Ayahuasca: Pharmacology, neuroscience and therapeutic potential

Behavioral Changes Over Time Following Ayahuasca Exposure in Zebrafish

The combined infusion of Banisteriopsis caapi stem and Psychotria viridis leaves, known as ayahuasca, has been used for centuries by indigenous tribes. The infusion is rich in N, N-dimethyltryptamine (DMT) and monoamine oxidase inhibitors, with properties similar to those of serotonin. Despite substantial progress in the development of new drugs to treat anxiety and depression, current treatments have several limitations. Alternative drugs, such as ayahuasca, may shed light on these disorders. Here, we present time-course behavioral changes induced by ayahuasca in zebrafish, as first step toward establishing an ideal concentration for pre-clinical evaluations. We exposed adult zebrafish to five concentrations of the ayahuasca infusion: 0 (control), 0.1, 0.5, 1, and 3 ml/L (n = 14 each group), and behavior was recorded for 60 min. We evaluated swimming speed, distance traveled, freezing and bottom dwelling every min for 60 min. Swimming speed and distance traveled decreased with an increase in ayahuasca concentration while freezing increased with 1 and 3 ml/L. Bottom dwelling increased with 1 and 3 ml/L, but declined with 0.1 ml/L. Our data suggest that small amounts of ayahuasca do not affect locomotion and reduce anxiety-like behavior in zebrafish, while increased doses of the drug lead to crescent anxiogenic effects. We conclude that the temporal analysis of zebrafish behavior is a sensitive method for the study of ayahuasca-induced functional changes in the vertebrate brain.

The alkaloids of Banisteriopsis caapi, the plant source of the Amazonian hallucinogen Ayahuasca, stimulate adult neurogenesis in vitro

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.

A Physician's Attempt to Self-Medicate Bipolar Depression with N,N-Dimethyltryptamine (DMT)

N,N-dimethyltryptamine (DMT) is a psychoactive substance that has been gaining popularity in therapeutic and recreational use. This is a case of a physician who chronically took DMT augmented with phenelzine in an attempt to self-medicate refractory bipolar depression. His presentation of altered mental status, mania, and psychosis is examined in regards to his DMT use. This case discusses DMT, the possible uses of DMT, and the theorized mechanism of DMT in psychosis and treatment of depression, particularly involving its agonist activity at 5-HT1A, 5-HT2A, and 5-HT2C. It is also important to recognize the dangers of self-medication, particularly amongst physicians.

Potential Use of Ayahuasca in Grief Therapy

The death of a loved one is ultimately a universal experience. However, conventional interventions employed for people suffering with uncomplicated grief have gathered little empirical support. The present study aimed to explore the potential effects of ayahuasca on grief. We compared 30 people who had taken ayahuasca with 30 people who had attended peer-support groups, measuring level of grief and experiential avoidance. We also examined themes in participant responses to an open-ended question regarding their experiences with ayahuasca. The ayahuasca group presented a lower level of grief in the Present Feelings Scale of Texas Revised Inventory of Grief, showing benefits in some psychological and interpersonal dimensions. Qualitative responses described experiences of emotional release, biographical memories, and experiences of contact with the deceased. Additionally, some benefits were identified regarding the ayahuasca experiences. These results provide preliminary data about the potential of ayahuasca as a therapeutic tool in treatments for grief.

Classical hallucinogens and neuroimaging: A systematic review of human studies: Hallucinogens and neuroimaging

Serotonergic hallucinogens produce alterations of perceptions, mood, and cognition, and have anxiolytic, antidepressant, and antiaddictive properties. These drugs act as agonists of frontocortical 5-HT_2A receptors, but the neural basis of their effects are not well understood. Thus, we conducted a systematic review of neuroimaging studies analyzing the effects of serotonergic hallucinogens in man. Studies published in the PubMed, Lilacs, and SciELO databases until 12 April 2016 were included using the following keywords: "ayahuasca", "DMT", "psilocybin", "LSD", "mescaline" crossed one by one with the terms "mri", "fmri", "pet", "spect", "imaging" and "neuroimaging". Of 279 studies identified, 25 were included. Acute effects included excitation of frontolateral/frontomedial cortex, medial temporal lobe, and occipital cortex, and inhibition of the default mode network. Long-term use was associated with thinning of the posterior cingulate cortex, thickening of the anterior cingulate cortex, and decreased neocortical 5-HT_2A receptor binding. Despite the high methodological heterogeneity and the small sample sizes, the results suggest that hallucinogens increase introspection and positive mood by modulating brain activity in the fronto-temporo-parieto-occipital cortex.

Ayahuasca enhances creative divergent thinking while decreasing conventional convergent thinking

INTRODUCTION

Ayahuasca is a South American psychotropic plant tea traditionally used in Amazonian shamanism. The tea contains the psychedelic 5-HT2A receptor agonist N,N-dimethyltryptamine (DMT), plus β-carboline alkaloids with monoamine oxidase-inhibiting properties. Increasing evidence from anecdotal reports and open-label studies indicates that ayahuasca may have therapeutic effects in treatment of substance use disorders and depression. A recent study on the psychological effects of ayahuasca found that the tea reduces judgmental processing and inner reactivity, classic goals of mindfulness psychotherapy. Another psychological facet that could potentially be targeted by ayahuasca is creative divergent thinking. This mode of thinking can enhance and strengthen psychological flexibility by allowing individuals to generate new and effective cognitive, emotional, and behavioral strategies. The present study aimed to assess the potential effects of ayahuasca on creative thinking.

METHODS

We visited two spiritual ayahuasca workshops and invited participants to conduct creativity tests before and during the acute effects of ayahuasca. In total, 26 participants consented. Creativity tests included the "pattern/line meanings test" (PLMT) and the "picture concept test" (PCT), both assessing divergent thinking and the latter also assessing convergent thinking.

RESULTS

While no significant effects were found for the PLMT, ayahuasca intake significantly modified divergent and convergent thinking as measured by the PCT. While convergent thinking decreased after intake, divergent thinking increased.

CONCLUSIONS

The present data indicate that ayahuasca enhances creative divergent thinking. They suggest that ayahuasca increases psychological flexibility, which may facilitate psychotherapeutic interventions and support clinical trial initiatives.