Ayahuasca may enhance memory recollection in experienced users

Ayahuasca, a traditional Amazonian brew known for its psychedelic effects, appears to enhance certain aspects of memory, according to a recent study in the Journal of Psychopharmacology. When experienced users took the brew before viewing a series of scenes, their memory for those scenes improved—particularly their ability to vividly recall specific details. This memory boost was selective, as it did not increase false memories or their general feeling of familiarity with the scenes.

Ayahuasca is a psychoactive brew originating from the Amazon region. It is traditionally made using two plants: Psychotria viridis and Banisteriopsis caapi. Psychotria viridis contains a compound called dimethyltryptamine (DMT), which produces strong psychedelic effects. Banisteriopsis caapi contains beta-carbolines, which are necessary for ayahuasca’s psychoactive properties. These beta-carbolines inhibit an enzyme that would otherwise break down DMT in the stomach, allowing it to reach the brain and take effect. Ayahuasca is used in ceremonies by several religious groups and is known for its ability to alter perception, mood, and thought processes, similar to other psychedelics.

Previous studies on psychedelics had shown a specific pattern of memory effects. These studies suggested that psychedelics tend to weaken the detailed, vivid recall of events—known as recollection—while leaving intact, or even enhancing, the more general feeling of knowing something, called familiarity. This pattern contrasts with how other substances like alcohol or ketamine impair both recollection and familiarity.

The researchers wanted to see whether ayahuasca would produce this same effect on recollection and familiarity. They were also interested in whether ayahuasca might influence false memories—memories for things that did not actually happen—since psychedelics can alter perception and increase suggestibility. They hypothesized that ayahuasca might impair recollection, enhance familiarity, and increase susceptibility to false memories.

“We previously found that psychedelics impair the formation of hippocampal-dependent recollections (memory for details such as where and when an event took place) while sparing or even enhancing the formation of memories based on cortical-dependent familiarity (knowing that something has recently been experienced without necessarily recalling specific details),” said study author Manoj Doss, a research fellow at The University of Texas at Austin Dell Medical School in the McGill Center for Psychedelic Research and Therapy and the Department of Psychiatry and Behavioral Sciences.

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“This was a rather unique effect of psychedelics, as most other drugs (alcohol, ketamine, THC) tend to impair the formation of both types of memory. We were hoping to replicate this effect with another psychedelic, ayahuasca/DMT. Moreover, in contrast to how memories are formed, when one retrieves a previously formed memory under the effects of most psychoactive drugs, there tends to be memory distortions or false memories—memories for events that were never experienced.”

To examine ayahuasca’s effects on memory, the researchers conducted a study with 24 members of the Santo Daime church, a religious group that uses ayahuasca as part of its ceremonies. These participants were highly experienced, having consumed ayahuasca hundreds of times over many years. The study took place over two sessions. In one session, participants were sober, serving as a baseline. In the other session, they consumed ayahuasca in a ceremonial setting. (The researchers did not provide the ayahuasca; instead, participants consumed their usual dose prepared by their church. However, the researchers analyzed a sample of the brew to determine the concentrations of DMT and beta-carbolines.)

During both the sober and ayahuasca sessions, participants completed a memory task designed to test different aspects of memory, including their ability to recall details and their susceptibility to false memories. The task involved three phases: encoding, misinformation, and retrieval.

In the encoding phase, participants viewed six different black-and-white scenes, such as a classroom or a beach, for 40 seconds each. They were asked to pay close attention to the details because their memory would be tested later. After viewing each scene, they rated how familiar it felt to them.

After encoding, participants completed a short, unrelated puzzle task before moving on to the misinformation phase. Here, they read descriptions of the scenes they had just viewed. These descriptions, presented as if written by other people, contained both accurate and misleading details. For example, a description of a beach scene might correctly mention a towel that was in the image but falsely suggest that there was a beach umbrella. Participants were told that some of the descriptions might contain errors.

After another puzzle task, participants moved to the retrieval phase, where their memory was tested. For each scene, they were shown a series of objects and asked whether the object had been present. Some objects had been in the scene (targets). Some had been present but also mentioned in the misleading descriptions (suggested targets). Others were not present but were falsely suggested in the descriptions (suggested lures). Some were conceptually related to objects in the scene but were not actually there (related lures). Lastly, some objects were entirely unrelated (unrelated lures). For each object, participants answered yes or no and then rated their confidence in their answer.

Doss and his colleagues analyzed the participants’ responses to see how ayahuasca affected their memory. They measured how often participants correctly identified objects that were actually in the scenes (hit rates) and how often they falsely recognized objects that were not there (false alarm rates). They also assessed metamemory, or a person’s awareness of their own memory accuracy.

The results were unexpected. Instead of impairing memory, ayahuasca enhanced it. Participants were better at correctly identifying objects they had actually seen, particularly in measures of recollection.

“We surprisingly found that ayahuasca enhanced the formation of recollections with no impact on familiarity or false memories,” Doss told PsyPost. “However, there may have been a few reasons for this. One, this study was an observational study of members of the Santo Daime community, most of whom had taken ayahuasca hundreds of times. Thus, psychedelics may differentially impact such experienced individuals.

“Another important caveat is that when the ayahuasca sample was analyzed, it turned out that the amount of DMT was extremely low, but the doses of beta-carbolines (monoamine oxidase inhibitors that allow DMT to be orally active) were substantial. Other drugs that increase synaptic monoamines can enhance the formation of hippocampal-dependent memories (e.g., amphetamine), so we speculated that the beta-carbolines may have contributed to the enhanced recollection.”

Interestingly, ayahuasca did not increase the participants’ general feeling of familiarity with the scenes, nor did it make them more prone to false memories. Participants were no more likely to mistakenly recall objects that were not there, even when those objects were suggested in the misleading descriptions. Ayahuasca also did not alter their awareness of their own memory accuracy.

“In addition to the surprising enhancement of recollection, participants appeared to have relatively high levels of familiarity both on and off ayahuasca compared to my past work,” Doss noted. “Although it’s hard to compare to past studies that used different tasks, it’s possible that repeatedly driving cortical plasticity with psychedelics over several years could lead to long-lasting enhancements of familiarity-based memory. However, heightened familiarity isn’t necessarily a good thing—it can sometimes lead to cognitive illusions such as déjà vu or presque vu (illusory insight), and in some cases, false memory.”

The researchers acknowledged some limitations. Since this was an observational study, they could not rule out the possibility that the memory enhancement was due to factors other than ayahuasca, such as practice effects. However, they argue that practice effects alone are unlikely to fully explain the findings, as the improvements were substantial and specific to recollection. Other aspects of memory, such as false memory susceptibility and metamemory, did not improve across the two sessions.

Future research could use controlled designs, including placebo groups and less experienced ayahuasca users, to confirm these findings. Further studies could also explore the specific roles of DMT and beta-carbolines in memory, potentially uncovering ways to harness ayahuasca’s memory-enhancing properties while minimizing any drawbacks.

“Many psychoactive drugs produce global cognitive impairments, including psychedelics,” Doss explained. “Using more granular measures of cognition, we’re hoping to find cognitive processes uniquely enhanced by psychedelics, which could have implications for how to better use these drugs in therapy, as well as other indications such as purported tools for facilitating creativity.”

“If beta-carbolines can truly enhance the formation of hippocampal-dependent memory, then in addition to potentiating the effects of psychedelics (they can also be administered with psilocybin to prolong/heighten psychedelic effects), they may also offset some of the recollection impairments produced by psychedelics, thereby better allowing one to remember specific details from their psychedelic experiences such as insights.”

The study, “Ayahuasca enhances the formation of hippocampal-dependent episodic memory without impacting false memory susceptibility in experienced ayahuasca users: An observational study,” was authored by Manoj K. Doss, Lilian Kloft, Natasha L. Mason, Pablo Mallaroni, Johannes T. Reckweg, Kim van Oorsouw, Nina Tupper, Henry Otgaar, and Johannes G. Ramaekers.