Psilocybin Therapy Demonstrates Efficacy in Treating Patients with Major Depressive Disorder

A recent clinical study explored the use of psilocybin therapy as an adjunct to psychotherapy in patients with treatment-resistant depression. Most study participants demonstrated a clinically significant response to psilocybin therapy, with over 50% of patients exhibiting remission from major depressive disorder (MDD).

More than 264 million individuals of all ages are affected with MDD worldwide. Over 20% of adults in the US will be diagnosed with depression at least once during their lifetime. The resulting economic burden to public health resulting from MDD alone is therefore substantial. This burden is further compounded by existing diagnostic and therapeutic modalities for MDD that have demonstrated outcomes neither robust nor reassuring when evaluating patient quality-of-life following their administration. Treatment of MDD currently involves therapeutic counseling from specialist medical practitioners, e.g., psychiatrists, psychologists, and/or general practitioners who may incorporate conjunctive pharmaceutical treatment into patient regiments. For those patients who do benefit from pharmaceutical treatment, up to 50% do not respond fully, i.e., they are unable to achieve complete remission from MDD. Up to 30% of patients administered clinically approved, FDA-certified pharmaceutical regiments for MDD do not respond at all, experiencing resistant to any form of treatment. Such treatment regiments have demonstrated little benefit when compared to placebo when administered to patients with treatment-resistant depression. Exploration of alternate forms of treatment for MDD such as psychedelics have been halted for almost a half-century since the 1971 UN Convention on narcotics banned all such substances for legal use throughout the globe. As a result, regulatory approval for clinical research and trials examining the effect of psychedelics in treatment of medical disorders is next to impossible, if not completely so. Thus, the current economic and societal burden of MDD has incurred in part due to restrictive legislative barriers that have historically prevented scientific, clinical exploration of alternate forms of treatment such as psilocybin.

Due in part to recent studies which have produced results indicating the substantial efficacy of psychedelics in treating conditions such as MDD, the FDA has recently granted “Breakthrough Therapy” designation to clinical trials involving psilocybin, allowing for the potential of this psychedelic to be medically approved for use in MDD and treatment-resistant depression.

This study, facilitated at the Center for Psychedelic and Consciousness Research in Baltimore, Maryland, examined the effect of psilocybin treatment on adult patients from 21 to 75 years of age with preexisting diagnosis of MDD. Study participants did not have any history of psychotic disorders, suicide attempts, or hospitalizations, and did not using any antidepressant medications prior to and during the study. Potential participants were excluded from the study if they had a “substantial” lifetime use, e.g., over 10 total, or recent use, e.g. within the past 6 months of ketamine, psilocybin, LSD, or other “classic” hallucinogens.

Participants were split into two groups, one receiving immediate treatment with psilocybin and another after an 8-week period of delay. Each group was given two day-long sessions of psilocybin along with at least 18 sessions of supportive psychotherapy interspersed throughout an 8-week duration. Treatment was differentiated into “immediate” and “delayed” interventions to differentiate psilocybin-associated improvements from those which occurred naturally, without any intervention.

Severity of MDD after psilocybin treatment was primarily assessed via the “GRID-Hamilton” Depression Rating Scale (GRID-HAMD).

Significantly lower depression scores were noted in the immediate treatment group when compared to the delayed treatment group (who had not yet received psilocybin treatment), indicating that psilocybin-assisted therapy was effective in producing “large, rapid, and sustained” antidepressant effects in patients with MDD. Data from this study corroborated that of other similar studies involving psilocybin and MDD in cancer patients and those with treatment-resistant depression. Data from this study, however, was collected from a demographic of individuals that more-closely represented the average individual with a diagnosis of depression, allowing results from this study to suggest that psilocybin therapy may be effective in treating a wider scope of MDD patients.

Though this study represented a more diverse array of MDD patients, this is only when considered in context of comparison to other studies involving psilocybin treatment (primarily involving atypical subsets of MDD patients, such as those with cancer). Most patients included in this study were of White non-Hispanic descent. Other limitations included a short-term period for follow up, and counseling sessions facilitated by those without formal medical training. Future studies will be needed to expound upon the data published in this work that include larger numbers of study participants, including those from a more diverse background representative of a global MDD population. Such studies, particularly when restricted to facilitation by licensed medical professionals, will be most likely able to provide data further supporting the efficacy of psilocybin for the majority of MDD patients when compared to traditional means of pharmaceutical treatment available today.


  • Ed Markey is a former special education teacher turned psychedelics enthusiast. His goal is to help shine a light on the emerging potential of psychedelics to help improve people's lives--focusing especially on writing in-depth pieces, research based, to help educate those interested in how psilocybin, MDMA, ketamine, and more can potentially help improve mental health (when taken in conjunction with medical supervision, in states where it is legal to do so).