Clinical Studies

How much more proof do you need?

“Modern-era published clinical trials evaluating psychedelics exceed 1,000, with the largest representation, by far, being psilocybin.”
— Gregory A Fonzo PhD American Journal of Psychiatry

“All modern-era published clinical trials evaluating psychedelics exceed 1,000, with the largest representation, by far, being psilocybin.”
— Gregory A Fonzo PhD American Journal of Psychiatry

Opioid Use Disorder

A 2022 paper authored by researchers from Harvard, Yale, and Columbia found that psilocybin use was associated with a 30% reduction in the rate of opioid use disorder.

A Study From the NIH of Over 134 Psilocybin Clinical Trials

Psilocybin has been given Breakthrough Therapy Designation by the FDA for treatment-resistant depression (TRD), indicating that it has shown substantial improvement over available therapies for severe conditions.

The study discusses clinical trials to evaluate psilocybin’s efficacy in treating various psychiatric disorders, mainly focusing on treatment-resistant depression. These trials have shown promising results:

Over two-thirds of participants in one study had a clinically significant response to psilocybin.

More than half of the participants were in remission at follow-up visits post-treatment.

Protective Effect Against Antisocial Behavior

Another population study found use of psychedelics like psilocybin predicted a 27% decrease in the odds of committing theft and a 22% decrease in the odds of arrest for a property crime.

Major Depressive Disorder pt.2

Results from a 2023 randomized trial published in the Journal of the American Medical Association revealed that a single 25-mg dose of psilocybin, administered with psychosocial support, was associated with clinically and statistically significant reductions in depressive symptoms and improvements in measures of functional disability compared to a placebo administered under an identical protocol.

Multidimensional Personality Changes Following Psilocybin-Assisted Therapy in Patients With Alcohol Use Disorder: Results From a Double-Blind, Placebo-Controlled Clinical Trial

A trial published in 2025 in the American Journal of Psychiatry (Vol. 182) found that psilocybin-assisted therapy reduced neuroticism and increased extraversion, with decreased impulsiveness linked to reduced alcohol consumption.

Magnesium–ibogaine therapy in veterans with traumatic brain injuries

This 2024 study examined the effects of a Magnesium-Ibogaine treatment protocol (MISTIC), combined with other therapies, on 30 male Special Operations Forces veterans with traumatic brain injury (TBI). The study found significant improvements in functioning immediately and one month after treatment, as well as reductions in PTSD, depression, and anxiety at the one-month mark.

VA-Funded Study on Psychedelic-Assisted Therapy

In December 2024, the VA announced funding for its first study assessing the potential benefits of psychedelics, including psilocybin, for treating PTSD and alcohol use disorder in veterans. This initiative underscores the VA’s commitment to exploring innovative treatments for mental health conditions prevalent among veterans.

Assessment of Psilocybin Therapy for Patients With Cancer and Major Depression Disorder

This 2023 nonrandomized controlled trial published in JAMA Oncology used a 1-to-1 therapist-to-patient ratio to administer psilocybin to groups of patients with cancer who were diagnosed with major depression disorder to create a scalable, rapidly effective depression treatment. A total of 30 participants were enrolled and completed the study per protocol. A sustained response was observed in 24 (80%) patients, with 15 (50%) patients showing complete remission of depressive symptoms.

Pilot Study on Psilocybin-Assisted Therapy

An open-label pilot study is underway to examine the safety and efficacy of two psilocybin administration sessions (15 mg and 25 mg), combined with psychotherapy, among U.S. military veterans with severe, treatment-resistant PTSD. The primary outcome measure for PTSD in this study is the Clinician-Administered PTSD Scale-5.

Johns Hopkins Center for Psychedelic and Consciousness Research - Upcoming Studies

The center has announced upcoming studies to determine the effectiveness of psilocybin as a new therapy for various conditions, including PTSD. This research aims to explore psilocybin’s potential in alleviating PTSD symptoms and contributing to mental health treatment advancements.

Food and Drug Administration (FDA) Designations Breakthrough Therapy Status

In 2019, the FDA granted breakthrough therapy status to psilocybin for treating depression, recognizing its potential based on preliminary research. While this designation primarily focuses on depression, it reflects the growing interest in psilocybin’s therapeutic applications, which may extend to PTSD in future studies.

Psilocybin-Assisted Group Therapy in Patients With Cancer Diagnosed With a Major Depressive Disorder

This 2024 article published in Cancer describes a phase 2, open-label trial that enrolled patients with curable and noncurable cancer and major depressive disorder at a single community oncology practice site. Thirty participants completed the study. The study’s findings showed safety (no treatment-related serious adverse events or suicidality) with psilocybin and suggested efficacy, with a significant reduction in depression severity scores.

Depression With Severe Treatment Resistance

A study published in January 2025 in the American Journal of Psychiatry documents a 2-week, open-label trial conducted at Sheppard Pratt Hospital. Participants were 18-65 years of age, in a major depressive episode with documented insufficient benefit from at least five treatments during the current episode. This open-label study suggested the efficacy and safety of psilocybin in severe TRD and supports further study of psychedelics in this population.

Psychedelics

when administered in a clinical setting with psychotherapeutic support—produce remarkably rapid, robust, and sustained improvements in a variety of psychiatric and addictive conditions.

Depression With Severe Treatment Resistance 2

An open-label study published in 2023 in Neuropsychopharmacology explored the safety, tolerability, and efficacy of psilocybin as an adjunct to a selective serotonin reuptake inhibitor in participants with TRD (Treatment-Resistant Depression). There were no severe treatment-emergent adverse events. Both response and remission were evident in 42.1% of participants.

Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder

This 2021 article published in JAMA Psychiatry investigates the effect of psilocybin therapy in patients with MDD (Major Depressive Disorder). This clinical trial was conducted at the Center for Psychedelic and Consciousness Research at Johns Hopkins Bayview Medical Center in Baltimore, Maryland. Findings suggest that psilocybin with therapy is efficacious in treating MDD

Reviewing the Potential of Psychedelics for the Treatment of PTSD

A 2020 review in The International Journal of Neuropsychopharmacology examined the potential of psychedelics for treating PTSD. The authors highlighted MDMA, ketamine, psilocybin, LSD, and cannabinoids as promising options, noting their ability to alleviate symptoms and enhance psychotherapy. They concluded, “Each compound provides unique qualities for the treatment of PTSD, from their use to rapidly target symptoms to their use as adjuncts to facilitate psychotherapeutic treatments.”

Major Depressive Disorder

A 2022 Johns Hopkins study investigated the effects of psilocybin on patients with major depression. At the 12-month follow-up, 75% of participants demonstrated a significant positive response, and 58% achieved remission. The authors concluded, “These findings demonstrate that the substantial antidepressant effects of psilocybin-assisted therapy may be durable at least through 12 months.”

Alcohol Use Disorder

A 2022 study that found participants given psilocybin-assisted therapy reduced heavy drinking by 83%.

Alleviation of Psychological Stress

Population research finds that the use of psychedelics is strongly associated with reduced psychological distress and suicidal thinking.

People Of Color In North America Report Improvements In Racial Trauma And Mental Health Symptoms Following Psychedelic Experiences

This study explored how psychedelics helped reduce symptoms of racial trauma among Black, Indigenous, and people of color (BIPOC) in North America. The survey, involving 313 participants, found that psilocybin, LSD, and MDMA led to significant reductions in traumatic stress and depressive symptoms following psychedelic use. The results suggest that these substances may offer therapeutic benefits for racial trauma.

67%

of patients with severe PTSD no longer met the diagnostic criteria for PTSD after an 18-week MDMA-assisted therapy program. SOURCE: Nature Medicine – Phase III Trial – MDMA-assisted therapy for severe PTSD

Multiple Recent Clinical Trials

show that a single treatment with psilocybin produced sustained decreases in anxiety and depression among patients with a life-threatening cancer diagnosis.

Psilocybin Care Has Potential

to be a cost-effective therapy for severe depression. The study used a decision-analytic model to evaluate the cost-effectiveness of psilocybin-assisted therapy compared to traditional antidepressant treatments.

Decreasing Suicidality

A meta-analysis involving several trials with psilocybin- assisted therapy found “large effect sizes for acute (80-240 min) and sustained (1 day, 1-8 weeks, and 3-4 months) decreases in suicidality” among people who received the treatment compared to the placebo group.

Psilocybin for Treating Substance Use Disorders?

This study investigates the safety and efficacy of psilocybin-assisted therapy in patients with treatment-resistant depression. The results suggest that psilocybin, when combined with psychotherapy, can lead to significant reductions in depressive symptoms, with many participants experiencing lasting improvements. The study highlights psilocybin’s potential as a treatment option for patients who have not responded to traditional antidepressants.

Efficacy and safety of psilocybin-assisted treatment for major depressive disorder: Prospective 12-month Follow-Up

The study investigates the effects of psilocybin as a potential treatment for anxiety and depression in patients with advanced-stage cancer. The research showed promising results, suggesting significant improvements in mental health following psilocybin-assisted therapy, with patients reporting reductions in symptoms of anxiety and depression. The findings support the need for further exploration into the therapeutic potential of psychedelics in palliative care settings.

Depression and Anxiety Among Cancer Patients

A study involving a group of patients with cancer-related anxiety and depression randomly assigned to psilocybin treatment found that at the 6.5-month follow-up, 60–80% of patients showed clinically significant reductions in depression or anxiety.

Psilocybin Therapy Increases Cognitive and Neural Flexibility in Patients With Major Depressive Disorder

This study, published in 2021 in Translational Psychiatry, tested 24 patients with major depressive disorder on the enduring effects of psilocybin therapy on cognitive flexibility, neural flexibility, and neurometabolic concentrations in brain regions implicated in acute psilocybin effects. Psilocybin therapy increased cognitive flexibility for at least four weeks post-treatment.

Psilocybin Produces Substantial and Sustained Decreases in Depression and Anxiety in Patients with Life-Threatening Cancer: A Randomized, Double-Blind Trial

In this double-blind trial from 2016 published in the Journal of Psychopharmacology, The effects of psilocybin were studied in 51 cancer patients with life-threatening diagnoses and symptoms of depression and/or anxiety. High-dose psilocybin produced significant decreases in depressed mood and anxiety, along with increases in quality of life, life meaning, and optimism, and decreases in death anxiety. At 6-month follow-up, these changes were sustained, with about 80% of participants continuing to show clinically significant decreases in depressed mood and anxiety.

Psilocybin-Assisted Group Therapy for Demoralized Older Long-Term AIDS Survivor Men: An Open-Label Safety and Feasibility Pilot Study

This 2020 study assessed the safety and feasibility of psilocybin-assisted group therapy for demoralization in older long-term AIDS survivor (OLTAS) men, a population with a high degree of demoralization and traumatic loss. Results demonstrated the feasibility, relative safety, and potential efficacy of psilocybin-assisted group therapy for demoralization in OLTAS. Groups may be an effective and efficient means of delivering psychotherapy pre- and post-psilocybin to patients with complex medical and psychiatric needs.

Clinical Trials

have shown that one or two doses of psilocybin, given in a therapeutic setting, can make dramatic and long-lasting changes in people suffering from treatment-resistant major depressive disorder.

Quality of Acute Psychedelic Experience Predicts Therapeutic Efficacy of Psilocybin for Treatment-Resistant Depression

This article discusses the potential therapeutic effects of psychedelics, specifically psilocybin, on mental health conditions like depression and anxiety. The review highlights various studies demonstrating positive outcomes, including symptom reduction and enhanced psychological well-being, while emphasizing the need for further research to understand the full scope of these substances’ therapeutic applications.

Therapeutic Alliance and Rapport Modulate Responses to Psilocybin Assisted Therapy for Depression

This 2022 study published in Frontiers in Pharmacology aimed to investigate the relationships between therapeutic alliance and rapport, the quality of the acute psychedelic experience, and treatment outcomes. The strength of therapeutic alliance predicted pre-session rapport and greater emotional breakthroughs. Future research could consider therapist training and characteristics that underlie the quality of the therapeutic relationship, the psychedelic experience, and clinical outcomes.

The Therapeutic Alliance in Psychedelic-Assisted Psychotherapy: A Novel Target for Research and Interventions

This article, published in 2023 in Psychedelic Medicine, establishes that investigations of the psychotherapy components of psychedelic-assisted therapy (PAT) have lagged behind other work. Years of research on different forms of psychotherapy reveal that one of the most important contributors to outcomes is the therapeutic alliance, a cooperative connection between clients and providers.

66%

of heavy smokers in a study quit smoking after two to three doses of psilocybin with cognitive behavioral therapy.

End of Life Anxiety

A study involving psilocybin-assisted therapy for cancer patients published in 2016 found that 80% of the study’s participants reported moderate to greatly increased well-being and life satisfaction.

60 TO 80%

of patients report clinically significant reductions in depression or anxiety, sustained benefits in existential distress, and quality of life after experiencing psilocybin-assisted therapy.