{Reference Type}: Journal Article {Title}: Endorsement of metaphysical idealism mediates a link between past use of psychedelics and wellbeing. {Author}: Jylkkä J;Krabbe A;Jern P; {Journal}: Sci Rep {Volume}: 14 {Issue}: 1 {Year}: 2024 06 10 {Factor}: 4.996 {DOI}: 10.1038/s41598-024-63687-4 {Abstract}: It has been proposed that psychedelics promote wellbeing through spiritual-type transformations, involving changes in metaphysical beliefs. Past empirical research shows a link between the use of psychedelics and the endorsement of non-physicalist metaphysical beliefs. However, non-physicalist beliefs encompass a wide range of metaphysical ideas, and their links to wellbeing and psychedelics use remain unclear. We utilized a cross-sectional Internet survey to probe the metaphysical beliefs of participants (N = 701) with past experience of classical psychedelics, using a novel 42-item questionnaire (Core Metaphysical Beliefs, CMB), encompassing a wide range of metaphysical beliefs. Factor analysis of CMB revealed two factors, Idealism and Materialism. In network analyses, Idealism was linked to psychological insight in a past psychedelic experience (E = 0.24) and average use of psychedelics (E = 0.16), and predicted wellbeing (Es = 0.13 and 0.22). Mediation analyses showed an indirect link from past psychedelics use through Idealism to wellbeing (ps ≤ .005). Non-Physicalist Beliefs or Materialism were not significant mediators. The results indicate that Idealism specifically, not non-physicalist beliefs generally, mediate a link between the use of psychedelics and wellbeing. Future research is required to establish whether the link is causal, and to understand what the Idealism factor means.