Overview of Research on Psychedelics and Psychedelic-Assisted Therapy

Research on psychedelics began in the 50s and 60s when LSD was first introduced to the US and was considered a new potential treatment for mental health problems such as schizophrenia or alcohol abuse. During this era, it was estimated that 40,000 patients received LSD treatment and that there were over 1000 scientific papers written on psychedelics. While many of these early studies are viewed as less rigorous through the lens of modern science, they did show promising results that suggested that more research was warranted. However, all psychedelic research was halted in the early 70s when psychedelics were scheduled as having no medical value and being highly dangerous. This early history of psychedelic research was not insignificant but has largely been excluded from mainstream psychiatry or psychology until recently. 

Over the last decade, there has been a dramatic increase in clinical trials investigating psychedelics, mostly in the area of MDMA-assisted therapy for the treatment of PTSD and psilocybin-assisted therapy for treatment-resistant depression and end-of-life distress. A meta-analysis of nine rigorous randomized-controlled trials indicated that the effects of psychedelic-assisted therapy were larger than established treatments and that they appeared to be enduring. The FDA has deemed that psilocybin and MDMA are breakthrough therapies, a status granted when preliminary evidence for a drug demonstrates substantial improvement over existing therapies resulting in expedited reviews of the drug and potential approval.

In order for a new drug to be approved for clinical applications, it must undergo a series of clinical trials that begin with establishing safety, piloting the treatment with a small sample of participants, and then increasing the number of participants to determine its effectiveness more accurately. MDMA-assisted therapy has been shown to be safe for the treatment of PTSD in early trials. Results from Phase-III trials demonstrated that 67% of participants no longer met the criteria for PTSD after 3 sessions of MDMA-assisted therapy and that an additional 21% had a clinically meaningful response. A second phase-3 trial is currently underway (as of October 2021) and is necessary for FDA approval with estimates that MDMA-assisted therapy will be available to the public in 2023. These early results are promising in indicating that MDMA-assisted therapy will provide relief to people with PTSD who have failed traditional treatments such as psychotherapy or medications. Once drugs are approved by the FDA for treatment of a specific condition, it is common for them to eventually be prescribed for “off-label” use with different conditions. Therefore, it is likely that once MDMA-assisted therapy is approved for PTSD, it will slowly be applied to other mental health conditions. There has already been some research on the use of MDMA-assisted therapy to treat social anxiety.

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Psilocybin-Assisted Therapy

Early clinical trials demonstrate that psilocybin-assisted therapy has been effective in treating depression. One study found that 67% of participants demonstrated a significant reduction in depressive symptoms and that four weeks after treatment 54% of participants no longer met the criteria for depression. A related application has been the use of psilocybin to treat distress associated with end stages of life. In a study of end-of-life cancer patients, 80% of participants showed improvements in anxiety and depression that endured for seven months. In several studies using psilocybin, many participants rank the experience as one of the most meaningful experiences of their life. Psilocybin has also been explored for its potential to treat alcohol abuse and nicotine addiction. The number of clinical trials investigating psilocybin-assisted therapy has been steadily increasing over the last decade and will likely continue to proliferate as additional evidence gathers and psilocybin’s legal status changes.


Ketamine is a dissociative drug with psychedelic properties depending on various factors such as the dose and setting. There are two main ways in which ketamine is currently being used in mental health treatment. The first is ketamine infusions for the treatment of depression which currently has the most scientific evidence. Ketamine infusions are typically used in cases where traditional treatments have failed, but one downside is that many who experience benefits need to continue with regular ketamine infusions and this treatment can be expensive.

In most settings, ketamine infusions are delivered without any psychotherapeutic components such as preparation or integration. In this medical model, the psychedelic and psychological experiences are not valued as much as the pharmacological properties of the drug itself.

The second way that ketamine is being used is called ketamine-assisted psychotherapy (KAP) and is more similar to MDMA- or psilocybin-assisted therapy. KAP involves a combination of medicine and psychotherapy and has emerged as a currently available approach because it is a legal drug that is relatively safe and can be prescribed by doctors. Here, the psychological experience under ketamine is more valued and believed to have therapeutic benefits. To date, there has been less research on this model, so it is uncertain what conditions it is most effective for or if there are contraindications.

There are many places to receive ketamine treatment. Individuals interested in this form of treatment are encouraged to become more educated on the potential risks and benefits. For a list of ketamine resources, please go here.

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