An investigation into the psychiatric and neuropsychological status of long-term ayahuasca users – conducted by the Human Experimental Neuropsychopharmacology group of Hospital Sant Pau (Barcelona), in cooperation with IDEAA and research centers in Brazil and Spain – found no evidence of adverse psychiatric or neuropsychological effects. The team performed a longitudinal study of ayahuasca users who had been drinking for at least 15 years, at least twice a month.
The Spanish and Brazilian research team, headed by psychologist José Carlos Bouso, evaluated several domains of mental health in 127 long-time ayahuasca users in religious contexts. They compared these participants with 115 non-users. To confirm the reliability of the results, they repeated the tests one year later. Interestingly, the ayahuasca users showed no personality disorders, and had lower psychopathological indices and better cognitive performance in some neuropsychological tests than the non-users. The study concludes that there is “no evidence of psychological maladjustment, mental health deterioration or cognitive impairment in the ayahuasca-using group.” These results are consistent with earlier results obtained by other research groups that had studied smaller samples of users. This is the first study with long-term ayahuasca users that both assessed a sample of this size and replicated the results. The authors indicate that the study sample was composed of people that have been using ayahuasca for many years, which is a clear sign that they tolerate the ayahuasca well. The researchers suggest that future studies should focus specifically on participants that initiate the use of ayahuasca and then stop because of a psychological issue possibly related to its use.
José Carlos Bouso is currently a member of the International Center for Ethnobotanical Education, Research & Service (ICEERS) and will be discussing the results of this study during the Interdisciplinary Conference on Psychedelic Research, to be held in Amsterdam on the 6th and 7th of October 2012.
The scientific article (both abstract and full text) can be found here.