The effect of psychedelic microdosing on animal behavior: A review with recommendations for the field

Microdosing, the repeated use of psychedelic substances at low doses, is growing in popularity among recreational consumers. While this practice is associated with many benefits to mood, well-being and health, research in this area is in its early stages and predominantly centered on human applications. In this narrative review, we synthesize the findings from studies investigating the effects of microdosing on the behaviors of three animal species: rats, mice, and zebrafish. A total of 12 studies were identified that implemented a microdosing regimen of LSD, psilocybin, or DMT in these animal models. Overall, microdosing caused little changes in behaviors associated with anxiety- and depressive-like states. Moreover, while microdosing was well-tolerated across species, further research is needed to capture specific safety concerns. Finally, we critically appraise the studies included in this review based on their methodologies and discuss further avenues of research to advance the preclinical literature on psychedelic microdosing. Specifically, we recommend that future research prioritize the replication of existing findings to inform the development of robust study designs and dosing protocols, as well as establish standardized methodologies to enable effective comparisons across different animal models. Furthermore, future investigations should explore the therapeutic potential of mescaline microdosing, examine sex-dependent effects, and extend research to additional models of psychiatric conditions, including those related to obsessive-compulsive disorder and post-traumatic stress disorder.