Serotonin, psychedelics and psychiatry

Serotonin is affected quite differently by SSRIs and psychedelics. The former is a multi-billion industry; the latter is poised to upend this. In this article, Carhart-Harris proposes how psychedelics affect serotonin and why they may work to help someone look at their environment in a new, better, way.

Abstract of Serotonin, psychedelics and psychiatry

“A simple and plausible model of therapeutic mechanisms of psychedelic treatments would greatly complement this ongoing clinical work. The thesis is put forward here that serotonin differentially encodes behavioral and physiological responses to uncertainty. More specifically, it is proposed that the limbic‐rich inhibitory postsynaptic 5‐HT1A receptor subtype provides basal control during normal conditions, via moderating emotion and anxiety, and promoting a generalized patience. On the other hand, the cortically‐rich 5‐HT2A receptor subtype is hypothesized to engage more during conditions of crisis, when the above‐mentioned default mechanism becomes suboptimal, e.g. when an individual’s internal and/or external milieu becomes so changeable and/or inconsistent with his/her prior beliefs and behaviors that significant revisions become mandated. Viewed through a Bayesian lens, it is proposed that the principal functional effect of 5‐HT2A receptor stimulation is to relax prior assumptions or beliefs, held at multiple levels of the brain’s functional hierarchy: perceptually, emotionally, cognitively and philosophically (e.g., in terms of biases). In so doing, it opens a door to heightened sensitivity to context, an ideal pre‐condition for effective change.”

Author: Robin L. Carhart-Harris

Summary of Serotonin, psychedelics and psychiatry

Serotonin is a key neuromodulator involved in brain development, perception, cognition, and mood. However, a compelling unified theory of serotonin function has not yet been established.

Serotonin has been implicated in several major psychiatric disorders, including depression. SSRIs remain the dominant treatment for unipolar depression, but have not significantly reduced prevalence.

Psychiatry has been a divided house historically, with the psychodynamic model dominating the first half of the 20th century, and the biomedical model ever since. The pharmacological model has been moderating over time, and this is especially evident in contemporary serotonin and depression research.

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Serotonin, psychedelics and psychiatry

https://www.doi.org/10.1002/wps.20555

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Cite this paper (APA)

Carhart‐Harris, R. L. (2018). Serotonin, psychedelics and psychiatry. World Psychiatry17(3), 358.

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Robin Carhart-Harris
Dr. Robin Carhart-Harris is the Founding Director of the Neuroscape Psychedelics Division at UCSF. Previously he led the Psychedelic group at Imperial College London.

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