Mechanisms of integration in psychedelic-assisted therapy

LAY SUMMARY Psychedelic pharmacotherapies combined with structured psychotherapy have shown promise in the treatment of several psychological conditions. This type of therapy is known as psychedelic-assisted psychotherapy (PAP) and includes three phases: preparation, in-session support, and integration. The purpose of this review was to identify randomized controlled trials (RCTs) that used psychedelics to treat a psychological condition and to summarize the literature on changes that may be associated with clinical outcomes, as measured with MRI and various psychologically based tools. Psychedelics were administered in 17 RCTs, and 16 of these did so within a PAP framework. A total of 19 studies were identified that looked at MRI or psychological outcomes during the integration phase. Changes in brain networks during integration were identified but were not consistent between studies because of small sample sizes and inconsistent methodology. Some evidence suggests that changes in the executive control network may occur after psychedelic administration. Psychological changes after psychedelic administration were related to cognitive flexibility and personality traits such as openness and neuroticism. Overall, studies in this field should be repeated with a greater number of participants and other MRI-based techniques.