It is arguably the most powerful hallucinogen on the planet, and until recently had been written off by lawmakers and academics as a dangerous narcotic, fit neither for consumption nor scientific investigation. Yet indigenous Amazonian communities have been using ayahuasca to treat all manner of physical and psychological ailments for centuries, and thanks to a recent spike in Western intrigue, the doors to research into this consciousness-altering liquid are finally opening.

What is Ayahuasca?

Ayahuasca is a psychedelic brew used in shamanic healing rituals and initiation rites throughout the Amazon. It is made by boiling the leaves of a plant called chacruna (Psychotria viridis) with the ayahuasca vine (Banisteriospsis caapi). The former contains a potent psychedelic compound called N,N-Dimethyltryptamine (DMT), which, interestingly, is found in nearly all the plants and animals we eat. However, upon arrival in the gut it is destroyed by an enzyme called monoamine oxidase, so it doesn’t reach the brain and produce its hallucinogenic effects.

That’s where the B. caapi comes in: It contains compounds called monoamine oxidase inhibitors that block these enzymes and ensure the DMT reaches the brain intact, resulting in an intense psychedelic trip, typically lasting four to six hours.

Banisteriopsis Caapi contains monoamine oxidase inhibitors that prevent enzymes in the gut from breaking down DMT. Image: Aya2 by Apollo via Flickr. CC BY 2.0

Is Ayahuasca Dangerous?

Jordi Riba, who studies the effects of ayahuasca on the human brain as part of the Beckley/Sant Pau Research Programme, told IFLScience that “the active principles from both B. caapi and P. viridis are cleared from the organism after a few hours, so toxicity and overdosing is very unlikely.”

However, while the brew may be safe from a physical perspective, Riba says that without the correct preparation, taking an ayahuasca trip can be psychologically damaging. “Some people may experience anxiety due to the intense and unusual nature of the experience. This is most often the case with travelers to the Amazon who take ayahuasca with people they don’t know or trust in an unfamiliar setting.”

Indeed, while members of indigenous Amazonian communities are primed from birth to be able to deal with the visions encountered during their ayahuasca trips, Western backpackers can often be overwhelmed by their psychedelic experiences.

What are the Benefits of Ayahuasca?

As scary as it sounds, the mind-expanding trip generated by ayahuasca has been found to have therapeutic value. “People who have taken ayahuasca report having been confronted with painful personal issues. They claim to have gained new insights into these issues, helping them to come to terms with them,” says Riba. “We have even seen people manage to overcome heavy cocaine and opiate addictions after a series of ayahuasca sessions.”

Amazingly, one Beckley/Sant Pau study found that taking ayahuasca produced an anti-depressant effect in individuals who had failed to respond to any other treatment for their depression. Even more remarkable was the fact that this improvement in symptoms was noticed almost immediately after the ayahuasca session and persisted for several weeks – a period Riba calls “the after-glow”, and which he says offers a “vital window of opportunity for psychotherapy,” as patients tend to be much more open and receptive at this time.

Harnessing the ayahuasca after-glow may, therefore, lead to faster, longer-lasting treatments than those currently used for depression, such as SSRIs. Uncovering the neurological mechanisms behind this after-glow effect is the next big challenge for ayahuasca researchers, and several pieces of the puzzle have already been discovered.

Ayahuasca is used by indigenous groups throughout the Amazon. Image: Lubasi via Wikimedia Commons

How Does Ayahuasca Work?

“We found that brain connectivity is changed in the 24 hours following an ayahuasca session,” explains Riba. During this period, “brain areas associated with creating and maintaining a sense of self become more connected with other regions that process emotions and autobiographical memories.”

Interestingly, the magnitude of this effect was found to correlate with an increase in certain key traits associated with mindfulness, which is one of the main goals of meditation and is measured using an array of scientifically validated questionnaires.

Delving deeper into the mystery, Riba and his team found that long-term ayahuasca users exhibit shrinkage to a brain region called the posterior cingulate cortex (PCC). Amanda Feilding, who founded and directs the Beckley Foundation, told IFLScience that the PCC is “a major hub center in the default mode network, which censors and represses perceptions, leading to the rigid patterns of thought and cognition that underlie psychological disorders like depression, addiction, and post-traumatic stress disorder.”

However, brain imaging studies have shown that under the effects of psychedelics like DMT, LSD and psilocybin, “the repressive control of the default mode network is lessened, so there’s more whole-brain connectivity and perception becomes much richer. It resets the psyche, and people often find that they can break free from their compulsive patterns of thought and behavior.”

Ayahuasca produces changes in brain activity that are similar to those seen during meditation, and lead to an increase in mindfulness. Image: Pixabay

The reduction in the size of the PCC may well mediate this effect in ayahuasca drinkers, although it is unlikely to be the only factor. For instance, a separate study revealed how a type of brainwave called alpha waves is markedly reduced during an ayahuasca trip.

Given that much of the activity of the default mode network is coordinated using alpha waves, it is perhaps unsurprising that this reduction was also correlated with an increase in mindfulness. Even more intriguing is the fact that a similar effect has been found in the brain during meditation, suggesting that both of these ancient healing practices may activate the same neurological circuits in order to bring about their therapeutic effects.

Overall, Riba claims that “ayahuasca’s three main areas of potential application are the treatment of addiction, depression and psychological trauma.” Yet as Feilding points out, “we are at the foothills of understanding how these compounds work,” and much more important research is needed if we are to unlock the secrets of this ancient hallucinogen.