Epidemiology of Hallucinogen Microdosing Among Young Adults in the United States: A National Study

The paper situates microdosing—regular consumption of very small amounts of psychedelics such as LSD or psilocybin—as a growing practice purported to produce subtle changes in mood and behaviour and to be used by some for self-management of depression, anxiety or substance-use problems. The authors note that despite survey evidence suggesting high lifetime incidence of microdosing among people who have tried psychedelics internationally, population-level prevalence and the epidemiological profile of microdosing in the United States remain poorly characterised. Young adults (aged 19–30) are identified as a key group because hallucinogen use concentrates in this developmental period and prior Monitoring the Future (MTF) data show increases in non-LSD hallucinogen use in recent years. The study sets out to estimate the national prevalence of past-year hallucinogen microdosing among US young adults, describe demographic correlates, and document co-occurring patterns of other substance use. The researchers focus on MTF panel respondents aged 19–30 surveyed in 2022–2023 and aim to compare characteristics of those who report any past-year microdosing with those who do not, and to contrast microdosing with any past-year hallucinogen use more broadly.

The study used cross-sectional analyses of data from the Monitoring the Future (MTF) panel, a nationally representative cohort initially sampled in 12th grade and followed biennially at modal ages 19/20, 21/22, 23/24, 25/26, 27/28 and 29/30. Participants included respondents who were in 12th grade from 2010–2022, selected for the panel, and who completed survey versions containing the relevant items at ages 19–30 in 2022 or 2023. The initial analytic frame comprised N = 3177 respondents; item-level missingness reduced sample sizes for specific analyses (maximum analytic N = 3094 for hallucinogen use after 83 missing, and maximum analytic N = 2860 for microdosing after 234 missing). Response rates for the longitudinal follow-ups averaged 61.5% across modal ages. Measures: Past-year hallucinogen use was assessed for LSD and other hallucinogens (examples given included psilocybin mushrooms) and respondents were asked whether they had "micro-dosed (took a very small amount of) a hallucinogen." Microdosing and hallucinogen use variables were dichotomised as any occasions in the past 12 months versus none. Other substance measures captured number of occasions in the past 12 months for alcohol and various modes of cannabis use (smoking, vaping, edibles/concentrates), nicotine vaping, and a combined category for any past-year amphetamine, cocaine or tranquilliser use. Past-30-day cigarette use and past-two-week binge drinking (5+ drinks) were also recorded and dichotomised. Demographic variables were taken from the 12th-grade survey (sex, race/ethnicity, parental education) with sex restricted to male/female analyses due to small counts in other categories. Race/ethnicity was recoded into mutually exclusive groups (Hispanic; non-Hispanic White; non-Hispanic Black; multi-race/other). Parental education was coded as at least one parent with a college degree versus not; college attendance at ages 19–30 was also queried. Statistical analysis: The researchers estimated weighted prevalence and demographic distributions for past-year microdosing versus not, and for any hallucinogen use, using analysis weights that accounted for selection probabilities, the complex survey design and predictors of participation. Logistic regression models produced odds ratios (ORs) and 95% confidence intervals (CIs) for demographic correlates. Prevalence of other substance use among microdosers versus non-microdosers (and among any hallucinogen users versus non-users) was examined, with multinomial logistic regressions reported as ORs and 95% CIs. Analyses were conducted using SAS survey procedures. The analyses were not pre-registered and item-missing data were excluded from analyses pertaining to those items.

Weighted prevalence estimates indicated that 9.5% (SE = 0.68) of the analytic sample aged 19–30 reported past-year hallucinogen use and 6.8% (SE = 0.61) reported past-year microdosing. Among respondents reporting any past-year hallucinogen use, 73.1% (SE = 3.6) reported at least one instance of microdosing in the past year. Demographic correlates of microdosing were broadly similar in direction and magnitude to those for any hallucinogen use. For microdosing, there were no statistically significant differences by sex, age, 4-year college attendance or parental education. Non-Hispanic Black respondents were less likely than non-Hispanic White respondents to report microdosing (OR 0.43, 95% CI 0.21–0.90). For any hallucinogen use, females were less likely than males to report use (OR 0.62, 95% CI 0.46–0.85), and Black respondents were less likely than White respondents (OR 0.35, 95% CI 0.19–0.66). Prevalence of microdosing and any hallucinogen use did not differ significantly between 2022 and 2023. Substance-use correlates showed substantially higher prevalence of other substance use among those who reported microdosing compared with those who did not. Nearly all analysed substances were more common among microdosers, with the exception of a single occasion of past-two-week binge drinking. Reported associations (ORs) ranged from 2.53 (95% CI 1.43–4.47) for any past-30-day cigarette use versus none, to 37.73 (95% CI 19.72–72.21) for reporting 3+ occasions of cannabis use in the past year versus none among microdosers compared with non-microdosers. As examples provided in the text: 72.4% of those who reported microdosing had 10+ occasions of past-year alcohol use (compared with 2.4% with 0 occasions within that group), while among those who did not report microdosing 44.9% had 10+ occasions and 17.3% had 0 occasions; the corresponding OR for 10+ versus 0 occasions of alcohol use was 11.82 (95% CI 3.73–37.44). For cannabis, 85.8% of microdosers reported 3+ occasions in the past year versus 5.3% reporting 0 occasions; among non-microdosers 27.0% reported 3+ occasions and 63.2% reported 0 occasions; the OR for 3+ versus 0 occasions of cannabis use was 37.73 (95% CI 19.72–72.21). The pattern and magnitude of associations for any hallucinogen use were similar to those for microdosing, with ORs ranging up to 26.26 (95% CI 14.56–47.35) for high-frequency cannabis use.

The authors interpret their findings as evidence that hallucinogen microdosing is relatively common among US young adults: roughly 1 in 15 reported past-year microdosing, and nearly three-quarters of past-year hallucinogen users reported at least one microdosing incident. They emphasise that people who report microdosing also report high levels of other substance use, particularly frequent alcohol and cannabis use and nicotine vaping, indicating that microdosing typically occurs in the context of polysubstance use rather than in isolation. The researchers position these results against limited clinical evidence for microdosing and broader hallucinogen research. They note that although some trials and earlier studies have reported modest mood benefits from microdosing, trial evidence is limited (small samples, inconsistent controls) and some trials have observed increases in anxiety. They also point out that many clinical protocols for therapeutic hallucinogen use employ substantially higher doses than those described as microdosing. Given these uncertainties, the high prevalence of co-occurring substance use among microdosers raises concerns that any putative benefits could be offset by harms associated with concurrent use of substances with established health risks. The authors acknowledge several key limitations: reliance on self-reported data which may be affected by recall bias or misunderstanding (respondents may not accurately identify a dose as a "microdose"); absence of information on frequency, timing, duration, motivations for microdosing, or simultaneous use with other substances, precluding causal or temporal inference about relationships between microdosing and other substance use; and limited generalisability because the MTF panel includes individuals originally sampled in high school (excluding those who dropped out) and is subject to differential attrition. They also note that subgroup sample sizes were small for some comparisons, producing wide confidence intervals. At the same time, the researchers highlight that the inclusion of a microdosing item in a nationally representative survey is a unique strength and argue that continued surveillance is important, particularly amid policy shifts in some US jurisdictions that decriminalise hallucinogens. Finally, the authors call for further research—particularly robust randomised trials focused specifically on microdosing regimens and more detailed epidemiological work on patterns, motivations and co-use—to better characterise potential benefits and harms. They suggest prevention and education efforts should treat microdosing within the broader context of polysubstance use given the strong co-occurrence observed.