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.
European Neuropsychopharmacology
January 16, 2015
José Carlos Bouso, Fernanda Palhano-Fontes, Antoni Rodrı́guez-fornells et al.
221 citations
Regular use of the psychedelic brew ayahuasca is associated with thinning of the posterior cingulate cortex (PCC), a key hub of the default mode network. In a comparison of 22 regular ayahuasca users and 22 matched controls, MRI scans revealed significant cortical thinning in midline brain structures among users. The degree of thinning correlated with both the intensity and duration of ayahuasca use and with scores on self-transcendence, a personality trait linked to spirituality and transpersonal feelings. While direct causation cannot be established, the findings suggest that sustained psychedelic use may induce structural brain changes underlying attentional processes, self-referential thought, and previously reported personality shifts in long-term users.
Psychopharmacology
June 20, 2013
José Carlos Bouso, Josep María Fábregas, Rosa María Antonijoan et al.
96 citations
Acute ayahuasca intake impaired working memory, as measured by increased errors on the Sternberg task, but reduced stimulus-response interference, shown by faster reaction times on the Stroop task with maintained accuracy. Performance on the Tower of London task, which assesses executive function, worsened only in occasional users, not in long-term experienced users. Greater lifetime ayahuasca use was associated with less impairment on the Tower of London. The findings suggest that prior exposure to ayahuasca may protect against acute cognitive disruption, possibly due to compensatory or neuromodulatory effects.
Psychopharmacology
December 1, 2002
Jordi Riba, Antoni Rodrı́guez-fornells, Manel J. Barbanoj
71 citations
Ayahuasca, a South American psychotropic plant tea containing the psychedelic DMT and beta-carboline alkaloids, produces diverging effects on two measures of neural gating. In a double-blind, crossover trial with 18 healthy volunteers who had prior psychedelic experience, ayahuasca caused significant dose-dependent reductions in P50 suppression, an operational measure of sensory gating. However, no significant effects were found on prepulse inhibition of startle (PPI), a measure of sensorimotor gating, or on startle response habituation at any prepulse-to-pulse interval tested. These findings indicate that ayahuasca disrupts sensory gating while leaving sensorimotor gating unaffected at the doses administered.