Brain Connectivity Pattern Changes Associated With Psychedelic-Assisted Psychotherapy

Psychedelic-assisted psychotherapy shows promise for treating psychiatric disorders, but how it works in the brain is not fully understood. A review of studies using fMRI found that psychedelics like LSD, psilocybin, and ayahuasca temporarily disrupt normal large-scale brain network patterns, reducing modular organization while increasing global connectivity—a state described as network disintegration and desegregation. This internal brain state relates to experiences like ego dissolution. One day after psilocybin treatment, changes in cerebral blood flow and resting-state connectivity were observed, including increased integrity and connectivity within the default mode network. The therapeutic benefits likely come from combining the drug with psychotherapy.

Study at a glance

Abstract

Psychedelic-assisted psychotherapy (PAP) has shown promising therapeutic benefits for various psychiatric disorders, but the underlying neural mechanisms remain unclear. This study aimed to investigate the effects of psychedelics on brain connectivity patterns using functional magnetic resonance imaging (fMRI). A comprehensive literature search was conducted in PubMed and Google Scholar databases using relevant keywords related to psychedelics, connectivity, therapy, and fMRI. Only studies involving major psychedelic compounds (LSD, psilocybin, ayahuasca) and measuring outcomes via fMRI were included. The findings from the reviewed studies suggest that psychedelics induce acute disruptions in normal large-scale brain network patterns, leading to a compromised modular but enhanced global connectivity, referred to as network "disintegration" and "desegregation." This "internal" brain state correlates with aspects of the psychedelic experience, such as ego dissolution. Post-acute effects, one day after psilocybin treatment, revealed changes in cerebral blood flow and resting-state functional connectivity compared to baseline, including increased default mode network (DMN) integrity and functional connectivity within the DMN. The proposed therapeutic mechanisms of PAP involve the synergistic combination of the psychedelic substance and the accompanying psychotherapy. Further research is warranted to delineate the specific brain connectivity changes associated with different psychedelic compounds and their relationship to therapeutic outcomes in various psychiatric conditions.