A study published in the British Journal of Pharmacology last month explored how ayahuasca (shortened to AYA for the use in this study) and DMT interacts with serotonin receptors in the part of the brain that regulates fear.
The authors explained that ayahuasca has been found to be useful in treating humans for depression, trauma, and drug use disorders, but little research has been conducted regarding how ayahuasca affects specific parts of the brain. Researchers specifically sought to examine ayahuasca’s effects on aversive memories, or negative memories.
Specifically, the study shows evidence of ayahuasca affecting fear memory extinction. While all living things develop a response to a stressful or fear-induced situation, fear memory extinction is when the subject’s response to a recurring stimulus is decreased over time.
Study author Leandro Jose Bertoglio, who is a professor of pharmacology at the Federal University of Santa Catarina in Brazil, told Psypost.org about the study approach.
“Our rodent lab investigates the brain and molecular mechanisms underlying memory formation during threatening or stressful experiences. We focus on developing pharmacological approaches to weaken the expression of aversive memories,” Bertoglio said. “Collaborators within our network are studying ayahuasca, a popular brew in Brazil and the Amazon, for its potential to treat depression and ethanol dependence. Given our expertise in fear extinction—the process where a neutral memory suppresses an aversive one—we are exploring ayahuasca’s impact on this process. The extinction likely forms the biological foundation for some psychotherapies.”
The study included 331 Wistar rats, which commonly exhibit freezing behavior in response to fear. Researchers applied a fear condition procedure twice per day, which would cause the rats to freeze, and recorded the amount of time that they froze to determine the fear extinction. Over time, they provided varying levels of ayahuasca to the rats.
The effects of ayahuasca were consistent with both on rats with 1-day-old memories, as well as those with 21-day-old memories, of the fear conditioning. Results show that all of these rats exhibited some form of fear extinction, even when different ayahuasca doses were administered.
Researchers explained that serotonin receptors (5-HT2A and 5-HT1A) in the part of the brain that manages fear, the infralimbic cortex, were being activated during ayahuasca use, and thus affecting fear extinction. “Orally administered ayahuasca accelerates fear extinction and its retention in female and male rats,” Bertoglio continued. “This effect is associated with N,N-dimethyltryptamine (DMT) and involves the activation of two serotonin receptor subtypes (5-HT1A and 5-HT2A) in the infralimbic cortex. This brain region, homologous to the ventromedial prefrontal cortex in humans, is crucial in regulating memory extinction.”
There are many studies that showcase the evidence of 5-HT2A receptor as it interacts with the use of psychedelic substances, but there is less known about the 5-HT1A receptor and how it interacts with psychedelics. “Compared to the 5-HT2A receptor, the participation of the 5-HT1A receptor in the effects of ayahuasca and other classical serotonergic psychedelics (e.g., psilocybin and LSD) has been less explored,” Bertoglio explained. “Our research aimed to elucidate the role of both receptors, demonstrating that DMT’s action on both 5-HT1A and 5-HT2A receptors contributes to enhanced fear extinction.”
Researchers concluded that ayahuasca facilitates “behavioral suppression of aversive memories in the rat infralimbic cortex,” which also suggests that both ayahuasca and DMT could be used to treat specific stress-related disorders.
According to Bertoglio, this research will open the door for more opportunities in the future to explore how psychedelics can affect long term fear memories, such as those suffered by post-traumatic stress disorder patients. “Our goal is to advance understanding of how and where psychedelic substances act when modulating the expression and persistence of aversive memories,” Bertoglio concluded. “These studies foster collaborations and their findings encourage related studies with humans.”
Personal accounts of patients seeking out ayahuasca treatment experiences have spoken out about the benefits they received. Heavyweight boxer and Olympic medalist, Deontay Wilder, recently spoke out in December 2023 about how he was “reborn” after experiencing ayahuasca treatment in Costa Rica. “Ah man, ayahuasca has been… man it’s been one of the top things in my life that I’m glad that I’ve experienced,” Wilder said. “One of the best journeys to experience, it’s been a beautiful thing for me and if you ask my wife [Telli Swift] she’ll say that it made me more sensitive, and she’s probably right, but it also made me happier as well.”
Other psychedelic substances are also being praised for providing unique benefits to patients, and the public opinion of psychedelics is quickly becoming mainstream. A recent study published in the American Journal of Bioethics Neuroscience this week found that nine out of every 10 Americans approve of psilocybin being administered in a controlled setting with the intention of treating specific conditions.
Another recent study published in Neuroscience Applied shows that psilocybin can actually reduce a person’s response to “angry facial expressions.” Researchers examined the amygdala part of the brain that regulates emotions. “We found that [the] amygdala response to angry faces was significantly reduced during exposure to psilocybin as compared to baseline, whereas no significant changes in amygdala responses to fearful or neutral faces were observed,” the authors wrote.
