Uncovering psychological mechanisms mediating the effects of drugs: some issues and comments using the example of psychedelic drugs.

Researchers have begun efforts to uncover the psychological mechanisms by which psychedelic drugs may have beneficial effects on long-term outcomes in some circumstances. The approaches several recent publications on the topic have taken to analyze such mechanisms have some pitfalls and limitations. Based on the rich literature on mechanisms and mediation analysis in psychological science, I comment on five particular issues: (1) Separating mediating and moderating factors, (2) problems inherent in using cross-sectional data, (3) statistical methods in mediation analysis, (4) assumptions and limitations inherent in traditional mediation analysis, and (5) criteria beyond mediation to establish a mechanism. Suggested practices for future research on the psychological mechanisms through which drugs have their effects are presented.