HEADLINE: No evidence of adverse psychiatric or neuropsychological effects found in study of long-term ayahuasca users.

An investigation into the psychiatric and neuropsychological status of long-term ayahuasca users has been conducted by the Human Experimental Neuropsychopharmacology group of Hospital Sant Pau, in collaboration with researchers from several Spanish and Brazilian research centers and the Institute for Applied Amazonian Ethnopsychology (IDEAA), directed by psychiatrist Josep Maria Fábregas. The study’s first author is psychologist José Carlos Bouso, currently a member of the International Center for Ethnobotanical Education, Research & Service (ICEERS).

The study, published by the scientific journal PLOS ONE, found no association between the long-term use of ayahuasca in a religious context and any mental health deficits. The ayahuasca users had higher scores in cognitive tests and lower psychopathological indices compared with the control group.

Ayahuasca is a psychoactive decoction made from the Amazonian plants Banisteriopsis caapi and Psychotria viridis, traditionally used by many Amazonian peoples in their healing and spiritual rituals. It is also extensively used in Brazil as a sacrament in the context of what are called ”ayahuasca churches," in which the use of ayahuasca is a central part of the doctrine. In Brazil, the use of ayahuasca in this context is so well integrated that the Brazilian government has specific laws to protect it. Also in the US, Canada, and the Netherlands, the religious use of ayahuasca by certain churches is legally protected or regulated, and in Peru ayahuasca has been declared a Cultural Heritage of the country. According to a 2010 report of the International Narcotics Control Board of the UN, ayahuasca is not under international control, although it contains the controlled substance DMT. This alkaloid is considered to be principally responsible for ayahuasca’s effects.

Interest in the study of the long-term effects of ayahuasca stems from the international expansion of its use in religious and other contexts.

The Spanish and Brazilian research team evaluated several domains of mental health in 127 ayahuasca users in religious contexts who had been drinking ayahuasca at least twice a month for at least 15 years. They compared these participants with 115 non-users. To confirm the reliability of the results, they repeated the tests one year later. The ayahuasca users showed no personality disorders, and had lower psychopathological indices and better cognitive performance in 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. 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.