New Study Reveals Suggestibility’s Role In Antidepressant Effects Of Psilocybin Therapy

A new study led by Balázs Szigeti and with involvement of researchers Brandon Weiss, Fernando E Rosas, David Erritzoe, David Nutt and Robin Carhart-Harris found evidence of suggestibility predicting an antidepressant response for patients receiving psilocybin therapy.

The study aimed to understand the link between pre-trial expectancy, suggestibility and response to treatment in a previously conducted clinical trial comparing escitalopram and COMPASS Pathways’ (NASDAQ:CMPS) synthetic psilocybin, COMP360, in the treatment of 55 patients with Major Depressive Disorder (MDD.)

The researchers analyzed the association between expectancy and six depression/well-being related outcomes in the two arms. They also assessed suggestibility-outcome associations in both arms. Here’s what they found:

Patients’ expectancy for psilocybin was “significantly higher” as compared to escitalopram – what study PI Szigeti called in jest “the most unsurprising result of the year.” 
Confirming previous results, expectancy for escitalopram was associated with improved therapeutic outcomes to the traditional SSRI.
Expectancy for psilocybin did not predict response to treatment with the psychedelic – “The big surprise” showed no expectancy-outcome association on none of the six scales.
If anything, it showed some “negative expectancy,” like higher expectancy more associated with worse outcomes, or higher depression and lower well-being scores, Szigeti added.
Pre-treatment trait suggestibility was associated with therapeutic response in the psilocybin arm, but not in the escitalopram arm.
In contrast with expectancy, higher suggestibility was strongly associated with better outcomes in the psilocybin arm, but not in the escitalopram arm.

Overall, researchers concluded that results suggest psychedelic therapy “may be less vulnerable to expectancy biases than previously suspected.”

Nonetheless, they added, the relationship between baseline influence suggestibility and response to psilocybin therapy does imply that highly suggestible individuals “may be primed for response” to the psychedelic treatment.

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Why It Matters

Author Brandon Weiss says that finding evidence of expectancy predicting an…