Insights on Psychedelics: A Systematic Review of Therapeutic Effects

Insights are a common and powerful subjective experience that frequently occur during psychedelic experiences, and are often considered by clinicians and patients to be central to the therapeutic value of psychedelics, but this has not been systematically assessed. Insight refers to a sudden acquisition of knowledge or understanding that is strongly felt to be true or real. In this systematic review, we analysed data from 98 studies reporting insight following a psychoactive dose of a classic-psychedelic, to elucidate several aspects of psychedelic-catalysed insight (PCI), including its prevalence, relationship to dose, time-course, and relationship to therapeutic outcomes in the context of mental health and wellbeing. Experiences of PCI were positively correlated with dose, and reached statistical significance in 43 of 46 (93%) studies that compared psychedelic and placebo conditions. Crucially, 25 of 29 studies (86%) found that PCI was associated with positive therapeutic outcomes, and this relationship was often stronger than mystical-type experiences, which have received more research attention. This systematic review contributes to our understanding of the aspects of subjective experiences that drive psychedelic-related outcomes, and suggests that PCI is an important topic for the clinical practice of psychedelic therapies and for understanding the mechanisms of psychedelic therapy more broadly.