Longterm effects of ayahuasca in patients with recurrent depression: a 5-year qualitative follow-up

Introduction

Ayahuasca is a traditional Amazonian botanical preparation that combines a Banisteriopsis caapi vine rich in β-carboline alkaloids (harmine, harmaline, tetrahydroharmine) with Psychotria viridis leaves that contain N,N-dimethyltryptamine (DMT). The β-carbolines act as reversible monoamine oxidase A (MAO-A) inhibitors and thereby render orally administered DMT centrally active; DMT itself acts primarily at serotonin receptors (including 5-HT1A/2A/2C). Earlier preclinical, observational and experimental work has implicated ayahuasca and its constituents in anxiolytic, antidepressant and antiaddictive effects, and studies in members of Brazilian ayahuasca churches and in controlled settings have reported tolerability and short-term reductions in anxiety and depressive symptoms. Dos and colleagues previously ran an open-label trial in 17 patients with treatment-resistant major depressive disorder that found statistically and clinically meaningful reductions on clinician-rated depression scales (HAM-D and MADRS) from about 80 minutes after dosing through day 21; a subsequent randomised, placebo-controlled trial with 35 patients produced similar short-term antidepressant signals. Despite these short-term findings, the long-term consequences of a single ayahuasca session in a clinical sample remained uncertain. This study therefore set out to explore possible long-lasting effects by conducting qualitative telephone interviews with volunteers 4–7 years after their single ayahuasca administration.