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Largest Ever Psilocybin Therapy Trial Shows Depressive Symptoms Rapidly Reduced

Updated: Jan 9, 2023

The results from the largest psilocybin therapy trial ever conducted, further validate the growing body of clinical research evidence demonstrating psilocybin as a highly effective option for treatment-resistant depression.

The largest-ever psilocybin therapy clinical trial was conducted by Compass Pathways, a mental health care company. The trial included 233 patients from 10 countries across North America and Europe. All patients had discontinued the use of antidepressant medications prior to the trial, 94% of the participants had no prior experience with psilocybin.

The trial was conducted using Compass Pathways's psilocybin therapy drug, COMP360. The researchers compared a 25mg and 10mg active dose against a 1mg dose of psilocybin administered along with psychological support from trained therapists.

"Patients who were administered 25mg showed a -6.6 difference on the Montgomery–Åsberg Depression Rating Scale (MADRS) at week three, compared to patients administered with just 1mg of COMP360. However, there was no statistically significant difference between the 10mg and 1mg doses at week three.

At least twice the number of patients in the 25mg group showed response and remission at week 3 and week 12, compared with the 1mg group. For patients in the 25mg group, the protocol-defined sustained response up to week 12 was 20.3%, compared to 10.1% for the 1mg group." reported Psychedelic Spotlight.

Dr. David J. Hellerstein, a professor of clinical psychiatry at Columbia University Irving Medical Center, who lead the trial described the study as “ground-breaking.”

“A single dose of psilocybin generated a rapid response that lasted up to 12 weeks,” he explained. “Remission rates appear to be higher than seen in traditional medication studies.”

During the trial, 179 of the study participants experienced treatment-emergent adverse events (TEAEs). 90% of these were mild to moderate in severity, most commonly headache, nausea, fatigue, and insomnia. 12 participants experienced severe adverse events including suicidal behavior, intentional self-injury, and suicidal ideation predominantly in the 25mg group.

As psychedelic-assisted trials continue, optimal dosage remains an important factor. While one of the goals of this trial was the determination of optimal dose, the significant number of TEAEs suggest that much more research is needed to identify an effective and safe dosage. Perhaps, psychedelic therapies will require a personalized medicine approach to ensure high efficacy and mitigate adverse events.


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While we believe that psychedelic medicines must be decriminalized, psychedelic substances are still considered  "Schedule I" substances in the US and continue to be subject to strong enforcement across nearly all states. The reader is responsible for checking their local rules and regulations and making informed decisions with all risk considerations. Microdose Guru does accept liability for its readers' personal choices. We are a strictly educational platform. 

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