Psychedelic Healing: A Historical,Empirical,and Personal Account

The resurgence in psychedelic medicine may be due in part to its applications to a number of mental health conditions, including depression, anxiety, PTSD, eating disorders, and substance use disorders, all of which appear to be growing in scale and suffering. In 2023, Oregon became the first state to legalize psilocybin for use in state-certified service centers. ¹ Psilocybin and other naturally occurring psychedelic substances have been used for millennia for healing and ceremony across many continents and cultures. Some speculate that psychedelic mushrooms may even have played a role in human evolution.^2,3 But it is over the past 30 years that the psychedelic renaissance has occurred, driven by a revived interest in the therapeutic potential of these substances, especially for mental health care. ⁴ This paper will examine 2 psychedelic medicines (psilocybin and ketamine) used as a part of an evidence-based treatment strategy. In addition to reviewing the literature, I will report on a current study in which I serve as both external researcher and participant-observer. The paper concludes by examining the interaction between psychedelics, nature, and healing.

A Brief History

Psychedelics have a long history of use in many cultures around the world. ⁵ For example, the Mesoamerican peoples of Mexico have used plants and fungi in religious, social, and curative ceremonies for centuries. ⁶ (For a comprehensive and accessible history, see Michael Pollan’s 2018 book How to Change Your Mind.) In the 1950s, as LSD research was in its heyday, psilocybin was “rediscovered” by the West. As anthropologist Ben Feinberg writes, “For outsiders, the history of the Sierra Mazateca area of Oaxaca began in 1955, when the American banker and mushroom enthusiast Gordon Wasson visited, participated in mushroom rituals, and then wrote about his experience for Life magazine”. ⁷ Wasson’s article led to a rush of foreigners visiting Mexico in an attempt to take part in these visionary quests, disrupting the small Mexican town of Huautla de Jiménez. (Feinberg’s chapter is a worthwhile read for a critique of the psychedelic renaissance which is often situated outside of cultural-historical context.)

Meanwhile, clinical research in the 1950s and 1960s produced hundreds of peer-reviewed articles in support of the clinical efficacy of LSD and other psychedelics for multiple mental health conditions. By the 1970s, research on psychedelics became more difficult to conduct. This was partially due to Richard Nixon’s War on Drugs but was also related to changing practices within pharmaceutical companies and within the FDA broadly. ⁸ In 1970, LSD, psilocybin, and similar drugs were classified as Schedule I (harmful, no therapeutic benefit) despite the fact that there was little evidence of harm and a plethora of promising, if preliminary, evidence of benefit.

After a several decade hiatus, clinical research on psychedelics resumed in the 1990s along 2 parallel paths: (a) the development of neuroimaging and psychopharmacological studies conducted in healthy volunteers, and (b) exploratory clinical studies. ⁹ As this research progressed, the scope broadened from LSD to studying many psychedelic medicines, with the strongest efforts directed at examining the effects of psilocybin, ketamine, and MDMA. MDMA-assisted therapies for PTSD are beyond the scope of this article; for a review, see Smith et al., 2022. ¹⁰

Psilocybin Research

Psilocybin is found in nature in over 150 mushroom species. When consumed, it is rapidly converted into the pharmacologically active metabolite psilocin. Psilocin produces its neuropsychological effects in the cortex, acting as an agonist at serotonin 5-HT_2A receptors. Psilocybin can produce a range of acute perceptual changes, subjective experiences, mood changes, and mystical experiences. There are, of course, many anecdotal reports from both clinical and non-clinical sources about the power of these mushrooms to enact change in individuals and groups. But it wasn’t until the 2000s that psilocybin began to be examined within well-designed studies as a potential evidence-based treatment for mental health challenges.

Leading the way has been Johns Hopkins University (JHU). In 2000, Roland Griffiths and his research group were the first to obtain regulatory approval in the U.S. to reinitiate research with psychedelics in healthy, psychedelic-naive volunteers. In a widely cited study, Griffiths and colleagues administered psilocybin to 30 volunteers in a placebo-controlled randomized study. ¹¹ The participants who received the psilocybin reported profound and sustained changes in perception and personal meaning, including a sense of having a mystical experience (e.g., feeling more connected to nature and the universe; experiencing ego dissolution). More than two-thirds of the participants reported that the experience had been one of the most meaningful and spiritually significant events of their lives.

Much of the research on psilocybin since the 2006 study has focused on treating mental illness. There have been more than 100 peer-reviewed studies published in the past 10-15 years. ¹² Most of the intervention studies follow a protocol in which psilocybin is administered as a part of psychedelic-assisted therapy (PAT). ¹³ Typically, a participant will undergo a screening, preparatory sessions, one or more psilocybin treatments with therapists present, and follow-up sessions. Important variables include dosage, set (one’s intentions/expectations), setting (where the study is conducted, with therapists, etc.), and type of psychotherapy conducted. The psilocybin effects generally last 3-6 hours, but the therapeutic session will last for 6 to 8 hours.

Outside of clinical trials, the only state which has approved therapeutic psilocybin use is Oregon. (Colorado is poised to become the second state as it finalizes the licensing requirements for healing centers and facilitators, expected to be in late 2024.) The following are several conditions for which psilocybin-assisted therapies appear to be beneficial. Some of these findings are derived from pilot studies limited by small samples, open-label designs, and lack of control conditions. That said, it is difficult to do placebo-controlled studies with psychedelics.

Smoking Cessation

Researchers at JHU conducted the first study to examine a psychedelic (psilocybin) to treat tobacco/nicotine addiction. The researchers found that 80% of participants were biologically verified as smoke-free 6 months after psilocybin treatment. ¹⁴ These changes are drastically higher than typical success rates, with the most effective medications showing success rates less than 35%. A follow-up study showed the percentage of abstainers remained high even after a year. ¹⁵

Cancer and Death Anxiety

Several rigorous studies have demonstrated that a single administration of psilocybin produces large and sustained decreases in depression and anxiety in patients with a life-threatening cancer diagnosis.^16-18

Major Depressive Disorder

Recent studies suggest that psilocybin-assisted therapy can produce large, rapid, and sustained reductions in depressive symptoms.^19-21

Eating Disorders

According to Gukasyan and her colleagues, 3 pilot studies examining the effects of psilocybin for people with anorexia nervosa have been ongoing since 2019. One of these studies found that 60% of the participants were in remission 3 months after the treatment. ²²

Mechanisms of Action

There are multiple pathways and mechanisms by which Psychedelic-Assisted Psychotherapy (PAP) may improve mental health. The following list is not exhaustive, but is an attempt to show that the mechanism of action likely occurs at multiple, interacting levels:

(1) Pharmacological (e.g., receptor-level effects related to 5-HT_2A agonism)

(2) Brain network level effects (e.g., changes in resting state functional connectivity and neuroplasticity)

(3) Psychosocial (e.g., changes in cognitive/psychological flexibility; a reduction in symptoms during the psychedelic intervention; a sense of universal connectedness)

(4) Behavioral (changes in lifestyle which may occur as a result of the intervention; see, for example, Psychedelics and Health Behaviour Change). ²³

Ketamine Research

Ketamine is an NMDA receptor antagonist with an anesthetic effect. ²⁴ Although it can be found in nature in certain fungi, ²⁵ the amount produced is so small that it must be synthesized for therapeutic effect. In the 1960s, Belgian scientists manufactured ketamine as an anesthesia medicine for animals. The FDA approved it as an anesthetic for humans in 1970, and it was used extensively in Vietnam to treat injured soldiers in the field. Studies in the 1990s pointed to the efficacy of NMDA receptor antagonists in animal models of depression, but it wasn’t until 2000 that the first randomized controlled trial in humans was published demonstrating ketamine’s antidepressant effects. ²⁶

Ketamine is used to treat pain, mental health, and substance abuse disorders due to its rapid-acting analgesic and antidepressant effects. There is now substantial evidence for its antidepressant qualities, including as an intervention for acute, suicidal depression and treatment-resistant depression.^27,28 In 2019, the FDA approved a nasal spray version of ketamine for use in patients with treatment-resistant depression. Another route of administration is sublingual ketamine, which can be taken outside of the medical clinic. Within a target dosage range (typically 200-400 mg sublingual), ketamine has psychedelic properties. Perhaps due to its relative ease of access, legality (generally legal to prescribe throughout the U.S.), efficacy, and shorter treatment/trip time (as compared to psilocybin), medical use of ketamine is surging.^29,30

Ketamine’s limited short-term durability has spurred researchers to investigate the synergistic actions between ketamine and psychotherapy to sustain benefits. ³¹ As with all psychedelics, it appears that when combined with integration/therapy, the benefits are more durable. ¹³ When the integration activities include interaction with nature, there also appear to be synergistic effects. ³²

An Insider’s Look

For the past 2 years, I have been studying a unique model of psychedelic-assisted therapy (PAT) that combines ketamine, group therapy, Internal Family Systems (IFS) therapy, and integration (e.g., nature-connection activities, art, movement). Internal Family System uses a non-pathologizing, accelerated approach to help patients utilize inner resources and self-compassion for treating symptoms of depression, anxiety, substance abuse, and other conditions. ³³ Its theoretical basis is one which posits that every human has a system of parts (e.g., protective and wounded parts) led by a core self. Because one of the goals of IFS is to unburden wounded parts, this form of therapy may be particularly effective for treating trauma. ³⁴

In examining the multimodal treatment model, Group Ketamine-Assisted Psychotherapy (GroupKAP), ³⁵ I am conducting both quantitative and qualitative research and was a participant-observer in one of the groups. Adult participants (N = 29) were recruited to participate in GroupKAP, providing informed consent for both treatment and research. Participants were permitted to be group members regardless of whether they met criteria for a clinical diagnosis; still, most participants self-identified as seeking treatment for mental health problems. Participants completed scales to assess depression, anxiety, and stress (DASS-21) ³⁶ and self-leadership. ³⁷ The latter scale assesses the 8 Cs of self-leadership as defined by the IFS model (confidence, connectedness, calmness, clarity, creativity, curiosity, courage, and compassion) which ostensibly should improve after an IFS-centered group therapy combined with ketamine therapy.

Participants joined one of 4 group cohorts (5-8 individuals each) which each took 6 weeks to complete. Following 2 orientation sessions, participants took part in 4 6-hour workshop days, each separated by a week. The workshops began with an opening circle: a space for 2 facilitators to help participants prepare for the day by sharing thoughts, feelings, and intentions in the group setting. Following the opening circle, participants collectively began the ketamine treatment (using 200-400 mg lozenges/troches) while the facilitators played recorded music and were available to assist as needed. Participants experienced the effects of the medication for about 1-2 hours. As effects of the ketamine began to wane, facilitators led integrative sessions (e.g., forest-bathing, yoga, art, journaling in nature) designed to assist participants in beginning to reflect upon their experiences. Two days after each ketamine session, there was a 2-hour IFS therapy session.

The results to this point have been remarkable. Granted, there is no control group, and there is no reliable way to determine which parts of the treatment model are driving the change. Still, in this pilot study, we saw reports of mental distress drop by 64% (t = 6.25, P < .001; effect size = 1.64). The DASS-21 figure below illustrates a composite score of the 3 subscales: depression, anxiety, and stress.

Further, while we don’t have enough long-term follow-up data to report with any confidence, there are early indications that the gains are being maintained up to a year later.

Participants also report significant improvements in their ability to self-lead (26% increase; t = −.3.98, P < .001; effect size = −1.05). The ability to self-lead was a target for the IFS-based therapy. Participants quickly began to use the language of self and parts, identifying ways in which they could become less blended with their anxious-depressed parts and more able to stay on track in their lives with a calm, curious, compassionate, and connected demeanor.

My own experience as a participant-observer in one of the cohorts was powerful and illuminating. As with many psychedelics, the experiences can be hard to capture. While some warn of conflating mysticism and psychedelic-psychological science, ³⁸ there indeed can be a radical departure from everyday perception that subjectively feels “mystical” (without a need to conjure spiritual or supernatural explanations). This has been my experience as a participant in this GroupKAP work, as well as in other informal therapeutic groups utilizing psilocybin for psychological growth and healing.

Within this qualitative methodology, and in an attempt to reduce researcher bias, a research assistant and I analyzed in-depth interviews (N = 6) conducted by another collaborator. We also reviewed responses of all participants to the open-ended questionnaires. Consistent with findings from Ko and colleagues, GroupKAP participants reported feelings of positive affect, a sense of sacredness, a noetic quality, a sense of unity, and a reduction in ego. ³⁹ Perhaps unique to this IFS-based model, multiple participants reported being able to dissociate in a safe, healthy way, allowing them to “unblend” (allowing the self to unmerge/separate from parts). The nature of ketamine as a dissociative-psychedelic medicine appears to complement the IFS approach.

The group therapy component also seems to be crucial. Several participants stated that while they had had previous positive experiences with ketamine at a clinic, the reductions in negative mood were not nearly as profound as the experience of engaging with KAP in a group. The felt sense of emotional support, rapport, vulnerability, and other psychosocial benefits illustrates the power of community in the context of psychedelic experiences. ⁴⁰ Another research team who utilized a GroupKAP model – in this case with frontline health care workers who were experiencing COVID-19-related burnout and PTSD – came to conclusions similar to ours: “Importantly, group therapy is cost-effective and addresses a core limitation found in the psychedelic framework around affordability. Access to KAP treatment in the U.S. is limited due to cost and availability of therapists. Using a group-based model for KAP, we reduced costs and increased the capacity of therapists to deliver treatment. Furthermore, participants reported they appreciated the shared experience, similar to the therapeutic factors observed in conventional group therapy settings” (p. 7). ⁴¹ (See also Trope et al., 2019 ⁴² )

Safety of Psychedelics

Psychedelic medicines are generally considered physiologically safe and typically do not lead to dependence or addiction. ⁴³ Both psilocybin and ketamine have good safety profiles when used in medical interventions and clinical trials. There are, however, concerns about potential for abuse with ketamine, especially as telehealth has made at-home use possible. Ketamine can be addictive and, when taken chronically in high doses, can cause bladder damage. ⁴⁴ Further, there are concerns that adverse events in psychedelic trials and interventions are poorly defined, not systematically assessed, and may be underreported. ⁴⁵ There are attempts to reduce adverse events by making training available to those who want to work as psychedelic-assisted therapists and/or facilitators. Currently, these facilitators are not regulated except in states where these therapies have been approved.

Psychedelics and Nature

Finally, it is important to briefly examine the relationship between psychedelics, nature, and healing. Most psychedelic medicines are found in or derived from nature. There is some evidence that combining psychedelic therapies with nature-based therapies is complementary and probably catalytic. For example, Gandy and colleagues ³² argue that practitioners should be utilizing nature-based settings and practices within psychedelic therapy (e.g., in preparation and integration), positing that “therapeutic psychedelic administration and contact with nature have been associated with the same psychological mechanisms: decreased rumination and negative affect, enhanced psychological connectedness and mindfulness-related capacities, and heightened states of awe and transcendent experiences, all processes linked to improvements in mental health amongst clinical and healthy populations” (p. 1). ³² Interestingly, psychedelic use may also lead to pro-environmental behavior (e.g., concern about climate change; increases in feelings of nature connectedness).^46-49

There is something profoundly moving about feeling your heart beat in sync with the universe. In several of my experiences with psychedelics (in both clinical research settings and therapeutic group settings), I have had a strong sense of connectedness to everything in nature and to everyone with whom I was sharing the experience. This is hard to quantify or explain with any sense of objectivity, but it is worth sharing since there are many reports of a decrease in ego combined with an increase in ecological consciousness within the psychedelic space. This is represented by the illustration below which helps place humans within the ecosystem rather than atop it. ⁵⁰

We are in early days with this work. There are no extant path analyses that can accurately identify the multiple interactions between nature, psychedelic medicine, group therapy, etc., in terms of the desired outcome: improved mental health. Nevertheless, as Mike Arnold (founder of Silo Wellness, which hosts psychedelic retreats in connection with nature) said: “Could you have this same experience without ketamine? Could you have the same experience with ketamine without a waterfall, or with the waterfall but without the group session? We’ll learn that over the years. But we can say this is a very enjoyable way of going about mental health. You’re going to go through a hard journey. You might as well have a beautiful view.” ⁵¹