Evidence of Efficacy
One of the main uses of ayahuasca in traditional cultures is as a medicine. This is the reason why in Western culture ayahuasca is popularly considered to have medicinal properties, even if it is used outside of its traditional context. However, the clinical evidence of the efficacy of ayahuasca to treat medical or psychological diseases is scarce. There are no clinical trials where efficacy of ayahuasca has been assayed, and there is only one follow-up study with patients (1). The evidence existing until now is anecdotal and based on very few subjects;
The classical work of Grob et al. (2), where a group of 15 regular ayahuasca users, all of them members of the Brazilian church Uniao do Vegetal, were interviewed, found that 11 out of the 15 participants had a history of moderate to severe alcohol use; 5 reported episodes of associated violent behavior and a diagnosis of alcohol abuse disorder prior to the involvement in the UDV; 4 subjects also reported previous use of other drugs of abuse, including cocaine and amphetamines; 8 of the 11 subjects who had a history of alcohol and other drug abuse were addicted to nicotine at the time of their first ayahuasca session; 2 subjects had past major depressive disorders; and 3 had past phobic anxiety disorders. The authors found that, at the time of the assessment, none of the UDV subjects had a current psychiatric diagnosis using the CIDI. According to the authors, all those problems were resolved as a consequence of their regular ritual use of ayahuasca.
A recent study (3) where 32 regular ayahuasca users belonging to the Igrejia do Santo Daime in Oregon (US) were assessed, also found that while most of them had shown some past psychiatric disorder or some drug or alcohol abuse disorder, at the time of the assessment only two of them reported an active psychiatric disorder. Again, the participation in the ayahuasca rituals is thought to be responsible of the reported benefits.
The only study (4) designed specifically to assess clinical efficacy of ayahuasca for medical disorder is an exploratory one, involving 3 female participants with a clinical diagnosis of recurring depressive disorder and current mild/severe depressive episode without psychotic symptoms. Subjects received an oral dose of 3ml/kg of ayahuasca. After a single ayahuasca dose, depressive symptoms were significantly decreased from 40 minutes after intake until day 14, when symptoms began to reach baseline levels.
Ayahuasca has also the reputation to be an efficient tool in the treatment of drug abuse disorders but, again, despite the anecdotal evidence cited above, there are no clinical studies that sustain that claim. Although there are some clinics throughout the world where addiction treatment programs with ayahuasca are provided, no data regarding efficacy has been published until now.
The increasing personal accounts of Ayahuasca’s role in therapeutic and personal growth practices emphasize the need for thorough clinical studies.