Psychedelics—a class of drug that acts on serotonin receptors in the brain, causing hallucinations—have been steadily gaining attention in the research community over the past ten years for their potential to treat a host of conditions.
Caitlin Thompson, 28, is one of many people who did her first ayahuasca ceremony not for medicinal purposes, but for a spiritual experience. “When I first did ayahuasca, I didn’t know I was sick,” she recalls. “I thought it was normal to sleep for 13 hours per day.” After her encounter, many of her symptoms faded and she realized how sick she'd been. She was subsequently diagnosed with Lyme disease, PTSD, and other chronic illnesses that she says she continued to manage with kambo, diet, and psychedelics.
Thompson is one of many “spiritual seekers” whose medical symptoms improve as a by-product of an ayahuasca ceremony. “I think I was opening up a spiritual door with other psychedelic experiences and I just wanted to keep going down the rabbit hole,” she says. In that sense, Thompson is an example of why many people in their 20s and 30s try ayahuasca. Brad Adams, a researcher I spoke with at UCLA, cites upcoming research that finds that most people don’t seek out ayahuasca for a specific ailment, but instead to experience the transformative feeling the drug is said to provide for many.
What makes Thompson unusual, however, is her background in neuroscience and chemistry. The way ayahuasca seemed to improve her wellbeing made her curious. After doing some digging, she found that one of the many things that ayahuasca might have positively affected was her microbiome. Thompson might have been onto something: Recent research and some leading researchers in the field suggest that psychedelics might affect your mind and body by changing your gut.
Microbiome is the term scientists use to refer to the collection of bacteria, fungi, archaea, viruses, and parasites colonizing our body. We have microbial colonies everywhere: our skin, our gut, and even our brain. The gut microbiome in particular has received a lot of attention because of the key role some researchers think it might play in a number of hard-to-treat disorders. Our gut bacteria getting all out of whack—a state technically known as dysbiosis—has been associated with several conditions, including GI disorders like IBS and psychiatric disorders like autism, anxiety, and depression.
“[The gut microbiome] has something to do with everything,” says Jane Foster, a microbiome researcher and head of the Foster lab at McMaster University in Hamilton, Ontario. At her lab, she and other researchers are studying the microbiome’s link to the brain, a connection researchers call the gut-brain axis. The gut-brain axis refers to the hormonal, neurological, and endocrine pathways that link the brain and the gut together—a system in which, Foster explains, all our body systems interact.
There’s a large overlap between disease caused by gut dysbiosis and the diseases for which psychedelics look promising as a treatment. Some researchers, including Thompson—who started her own probiotic company called Ethneozen to help people treat dysbiosis—suspect that psychedelics might heal both psychiatric and GI conditions by addressing dysbiosis. “If, in fact, psychedelics are having an impact on good bacteria or bad bacteria [in the gut],” Foster says, “then that impact—in either changing the numbers or changing the function of those bacteria—could have a positive impact on anxiety, depression, or GI disorders.”
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The idea that you can change your gut microbes isn’t new. Foster says the food you eat, the medication you take—even something like using a vape—can impact your microbiome over time, for better or worse. Antibiotics kill off microbes systemically, including the ones in our gut, thus altering our microbiome. While everything can impact our microbiome over time, antifungal, antibiotic, antiparasitic, and antiviral compounds tend to have a more drastic effect in the short term. As far back as the 1980s, research indicated that ayahuasca was antiparasitic, and now researchers are finding that it also contains compounds that show some antibacterial and antifungal activity, meaning that the brew almost certainly effects the good and bad bacteria in the gut. Adams’ study (and a few other shorter-term studies) show that psychedelics tend to help psychological disorders have more of a positive effect on gut bacteria than any other available treatments, indicating that it’s unlikely that it’s making changes for the worse if we’re seeing positive downstream effects.
Something called leaky gut syndrome can allow chemical messengers called inflammatory cytokines (which—you guessed it—signal an inflammation response) to leak out of the gut and circulate through your system, eventually reaching your brain. Once in the brain, these molecules can then stimulate a neural pathway called the hypothalamic-pituitary axis (HPA), the continual activation of which can cause problems over time, says Sarah Wakefield, a child and adolescent psychiatrist at Texas Tech University in Lubbock, Texas says. “[The HPA] is really our stress release axis that activates to tell our body that it’s time to be stressed out.”
HPA activation can be a good thing, Wakefield says, in much the same way that our immune system can be good until it goes rogue and starts attacking our own bodies instead of invaders. “Inflammatory cytokines can induce that HPA axis to function when it’s not helpful to function, which can eventually lead to anxiety and depression,” she adds. However, she points out that gut-brain axis is a “two-way street,” and that depression and anxiety can also create a stress response that can produce dysbiosis. In addition to disrupting an unhealthy state in the gut, ayahuasca might further aid microbiome imbalance by improving neurological patterns underlying anxiety, depression, and trauma that perpetuate dysbiosis.
Preliminary research also suggests that psychedelics including ayahuasca could improve symptoms of anxiety and depression by reducing production of inflammatory cytokines in the first place, nipping stress, depression, anxiety, and dysbiosis in the bud. Psychedelics act on serotonin receptors, which are distributed throughout the entire body but concentrated in the gut, Foster tells me. Serotonin signaling influences the immune system’s activity—a system that is, coincidentally, also housed in the gut. (Ayahuasca also been shown to impact immunity through a different kind of receptors called sigma-1 receptors, which are thought to also play a role in neurodegeneration.) In any case, it’s possible that psychedelics like ayahuasca could be helping people manage disease symptoms by treating dysbiosis and adjusting immunity through its impact on the gut.
While psychedelic therapy remains controversial, researchers agree that altering the microbiome’s composition could be important in treating diseases stemming from dysbiosis. “There’s no debate in my mind that these drugs are going to have an action on the bacteria themselves,” Foster says, noting that it could be helping people treat psychological conditions through other systems, too. Thompson stresses that the immense promise that psychedelics hold means that there is an even greater need for research into the direct link between psychedelics and the microbiome.
Questions of generality—what effect that action might cause and for whom psychedelics could be helpful, given individual differences in genetics, microbial colonies, environment, and access to those treatments—as well as the legality surrounding psychedelic treatments remain. One thing is certain, though: Through their impact on the microbiome, psychedelics have the potential to help treat several diseases that are reaching epidemic proportions. And if there’s one thing that could inspire hope during these dark days of ascending populism, environmental degradation, and robot sex, it’s that.
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