In 1993, a team of international researchers ventured into the Brazilian Amazon and set up a makeshift laboratory inside a temple of the União do Vegetal (UDV). Followers of the church drink a tea made from the psychoactive plant ayahuasca—which is known locally as “Hoasca”—as part of the religious service. Because Brazilian regulatory agencies had started to express concerns about the effects of long-term consumption, the church asked the researchers to conduct a study.
Nature and Neuroscience
Dennis McKenna, a celebrated ethnopharmacologist who participated in the biomedical study, described the experiment at a psychedelics science symposium in Los Angeles earlier this month. They ran tests on 15 male volunteers, ranging from basic vitals to psychiatric “life story interviews.” While there were plenty of compelling findings (no acute toxicity, slightly improved cognitive functioning, etc.), he said that one in particular stood out: compared to control groups, individuals who regularly drink “Hoasca” tea had higher levels of serotonin transporters.
“We had no idea what we were looking for, but guess what? When we did receptor binding profiles on platelets, which we had collected, we actually found a significant difference in the abundance, or the density, of serotonin transporters,” McKenna said. “So there is a difference, but what does that mean? Well, we didn’t really know—but we did what you do when you’re in that situation and went into the literature.”
People generally know serotonin as a neurotransmitter that regulates emotions and serves as a mood stabilizer. Serotonin transporters are proteins that aid in the facilitation of serotonin throughout the nervous system, and what McKenna and his team discovered in the existing scientific literature was that deficiencies of this protein were associated with various “pathologies,” including “certain kinds of alcoholism, alcoholism associated with violent or homicidal behaviors, suicidal behaviors, binge eating, and other disorders.”
The Power of the Plant
McKenna’s study was published in the Journal of Psychopharmacology in 1993—one of the first of its kind. Since its publication, more than 150 studies on ayahuasca now appear on PubMed, the federal database of peer-reviewed research.
“It’s almost too neat, but there it is,” McKenna said at the symposium. “It suggested that maybe ayahuasca could actually reverse these deficits—actually raise the expression of the serotonin transporters—and that might be therapeutic.”
That might help explain why many members of the UDV who participated in the study, as well as many ayahuasca users throughout the world, often seek out the psychoactive plants during times of crisis. Other research, including studies on rats, have come to similar conclusions about the peculiar, biochemical effect of ayahuasca consumption, but the plant remains in a grey legal area in the United States. The plant itself is not scheduled under federal drug laws; however, you can extract the potent hallucinogen DMT from the plant, which is classified in the strictest drug category, Schedule 1.
That’s unfortunate because, as McKenna emphasized during his speech, “[a]yahuasca is the only pharmacology that I know of… that does this—that upregulates the serotonin transporters,” making it a unique and potentially versatile therapeutic tool that has yet to be embraced by the broader, scientific community.