State Cannabis and Psychedelic Legislation and Microdosing Interest in the US

Despite growing interest in psychedelics, there is a lack of routine population-based surveillance of psychedelic microdosing (taking "subperceptual" doses of psychedelics, approximately one-twentieth to one-fifth of a full dose, over prolonged periods). Analyzing Google search queries can provide insights into public interest and help address this gap. To analyze trends in public interest in microdosing in the US through Google search queries and assess their association with cannabis and psychedelic legislative reforms. In this cross-sectional study, a dynamic event-time difference-in-difference time series analysis was used to assess the impact of cannabis and psychedelic legislation on microdosing search rates from January 1, 2010, to December 31, 2023. Google search rates mentioning "microdosing," "micro dosing," "microdose," or "micro dose" within the US and across US states were measured in aggregate. Enactment of (1) local psychedelic decriminalization laws; (2) legalization of psychedelic-assisted therapy and statewide psychedelic decriminalization; (3) statewide medical cannabis use laws; (4) statewide recreational cannabis use laws; and (5) all cannabis and psychedelic use restricted. Microdosing searches per 10 million Google queries were measured, examining annual and monthly changes in search rates across the US, including frequency and nature of related searches. Searches for microdosing in the US remained stable until 2014, then increased annually thereafter, with a cumulative increase by a factor of 13.4 from 2015 to 2023 (7.9 per 10 million to 105.6 per 10 million searches, respectively). In 2023, there were 3.0 million microdosing searches in the US. Analysis at the state level revealed that local psychedelic decriminalization laws were associated with an increase in search rates by 22.4 per 10 million (95% CI, 7.5-37.2), statewide psychedelic therapeutic legalization and decriminalization were associated with an increase in search rates by 28.9 per 10 million (95% CI, 16.5-41.2), statewide recreational cannabis laws were associated with an increase in search rates by 40.9 per 10 million (95% CI, 28.6-53.3), and statewide medical cannabis laws were associated with an increase in search rates by 11.5 per 10 million (95% CI, 6.0-16.9). From August through December 2023, 27.0% of the variation in monthly microdosing search rates between states was explained by differences in cannabis and psychedelics legal status. This cross-sectional study