Critical Period Plasticity as a Framework for Psychedelic-Assisted Psychotherapy.

Psychedelic-assisted psychotherapy may work by reopening a critical period of heightened neuroplasticity, similar to developmental windows when the brain is especially sensitive to environmental input. The paper proposes that psychedelics could remove molecular brakes on adult neuroplasticity, creating a brain state akin to neurodevelopment. Drawing on ocular dominance plasticity in the visual system as a model, the authors suggest this framework could help explain how combining psychedelic compounds with psychotherapy produces enduring clinical improvements in conditions like PTSD. The framework integrates neuroscientific inquiry with the influence of environment both in development and in therapy.

Study at a glance

Abstract

As psychedelic compounds gain traction in psychiatry, there is a need to consider the active mechanism to explain the effect observed in randomized clinical trials. Traditionally, biological psychiatry has asked how compounds affect the causal pathways of illness to reduce symptoms and therefore focus on analysis of the pharmacologic properties. In psychedelic-assisted psychotherapy (PAP), there is debate about whether ingestion of the psychedelic alone is thought to be responsible for the clinical outcome. A question arises how the medication and psychotherapeutic intervention together might lead to neurobiological changes that underlie recovery from illness such as post-traumatic stress disorder (PTSD). This paper offers a framework for investigating the neurobiological basis of PAP by extrapolating from models used to explain how a pharmacologic intervention might create an optimal brain state during which environmental input has enduring effects. Specifically, there are developmental "critical" periods (CP) with exquisite sensitivity to environmental input; the biological characteristics are largely unknown. We discuss a hypothesis that psychedelics may remove the brakes on adult neuroplasticity, inducing a state similar to that of neurodevelopment. In the visual system, progress has been made both in identifying the biological conditions which distinguishes the CP and in manipulating the active ingredients with the idea that we might pharmacologically reopen a critical period in adulthood. We highlight ocular dominance plasticity (ODP) in the visual system as a model for characterizing CP in limbic systems relevant to psychiatry. A CP framework may help to integrate the neuroscientific inquiry with the influence of the environment both in development and in PAP. Appeared originally in Front Neurosci 2021; 15:710004.