The Journal of Nervous and Mental Disease
February 1, 1996
Charles S. Grob, Dennis J. Mckenna, J. C. Callaway et al.
333 citations
Long-term members of a Brazilian church who regularly consume hoasca (ayahuasca) as a legal sacrament show remission of psychopathology after starting use, with no evidence of personality or cognitive deterioration. Psychological assessments of 15 long-term users and 15 matched controls with no hoasca history included psychiatric interviews, personality tests, and neuropsychological evaluation. Users reported high functional status. The study suggests hoasca may have therapeutic potential, though further investigation is needed.
Psychopharmacology
February 22, 2001
Jordi Riba, Antoni Rodrı́guez-fornells, Gloria Urbano et al.
302 citations
Ayahuasca, a South American psychoactive beverage containing DMT, produced dose-dependent psychological effects in six healthy male volunteers with prior experience. Encapsulated freeze-dried ayahuasca at doses of 0.5, 0.75, and 1.0 mg DMT/kg body weight increased scores on hallucinogen rating scales, addiction research inventory scales, and visual analogue scales for liking, good effects, and high. Effects began within 30-60 minutes, peaked at 60-120 minutes, and resolved by 240 minutes. The tea was well tolerated cardiovascularly, though nausea and altered physical sensations were common. Five volunteers found the experience pleasant; one had an intensely dysphoric reaction with anxiety and withdrew. Ayahuasca induced perceptual, affective, cognitive, and somatic changes of longer duration and milder intensity than intravenous DMT.
Journal of Analytical Toxicology
October 1, 1996
J. C. Callaway, Lionel P. Raymon, William Lee Hearn et al.
158 citations
After ritual ingestion of ayahuasca, the highest plasma concentrations in 15 healthy male volunteers were 222.3 ng/mL for harmine, 134.5 ng/mL for tetrahydroharmine, and 9.4 ng/mL for harmaline, with N,N-dimethyltryptamine (DMT) also quantitated. Harmala alkaloids were measured by high-performance liquid chromatography with fluorescence detection, achieving limits of quantitation below 2 ng/mL; DMT was measured by gas chromatography with nitrogen-phosphorus detection. Recovery was quantitative for all analytes. These are the first reported measurements of DMT and harmala alkaloids in human plasma following ritual ayahuasca ingestion. The methods may apply to other biological matrices.
Psychopharmacology
November 1, 1994
J. C. Callaway, Mauno M. Airaksinen, Dennis J. Mckenna et al.
79 citations
Healthy male drinkers of ayahuasca, a psychoactive Amazonian sacrament, showed an increased number of binding sites for [3H]citalopram on platelet serotonin transporters compared to healthy male controls, while the dissociation constant remained unchanged. If these platelet measures reflect neuronal serotonin uptake activity, the findings suggest either a decreased concentration of extracellular serotonin or a compensatory response to increased serotonin production and release. The authors caution that such changes in serotonin synaptic activity should not be misinterpreted as signs of developing neurological or psychiatric illness.
Journal of Psychoactive Drugs
June 1, 2005
J. C. Callaway
34 citations
Harmine, a main alkaloid in ayahuasca (hoasca), inhibits monoamine oxidase-A and the cytochrome P450 isozyme 2D6, which metabolizes harmine. CYP 2D6 has genetic variations that may cause different effects among users. In 14 experienced male members of the União do Vegetal who received a standardized dose of hoasca, two subgroups of CYP 2D6 phenotypes—fast and slow metabolizers of harmine—were identified. In their religious practice, the presiding mestre individually adjusts the hoasca dose to compensate for metabolic differences and variations in alkaloid content.