Use of psilocybin (“mushrooms”) among US adults: 2015-2018

Psilocybin, the principal psychoactive compound in many species of mushrooms, acts as a serotonergic prodrug to psilocin and has a long history of both recreational and investigational therapeutic use. Interest in its clinical potential for conditions such as depression, obsessive–compulsive disorder and substance dependence has resurged despite its Schedule I status, and prior studies report generally low physical toxicity but transient psychological side effects. However, the epidemiology of psilocybin use in nationally representative samples of US adults remains poorly characterised, limiting efforts to target prevention, harm reduction or service planning. Yockey and colleagues set out to estimate the lifetime prevalence of psilocybin use among US adults aged 18 and older and to identify demographic and substance‑use correlates. The study therefore aims to fill a gap in population‑level data on who reports ever using psilocybin and how that use relates to other illicit drug use, sociodemographic characteristics and sexual orientation.

The investigators analysed pooled data from the 2015–2018 National Survey on Drug Use and Health (NSDUH), an annual, nationally representative household survey of behavioural health, substance use and mental health in the United States and the District of Columbia. The analytic sample comprised 168,650 adults aged 18 years and older. Respondents completed computer‑assisted interviews, were compensated US$30 for participation, and the survey achieved weighted response rates between 67.3% and 71.0% across those years. The authors note NSDUH reliability metrics (kappa scores >0.80) and indicate that the institutional review board classified the analysis as non‑human‑subjects research because no identifying data were used. Lifetime psilocybin use was measured with a single item asking whether the respondent had “ever, even once, used psilocybin, found in mushrooms.” The analysis also included lifetime use indicators for LSD, heroin, marijuana, methamphetamine and cocaine. Key covariates were gender, age group, race/ethnicity (White, Black, Hispanic, Asian, other/mixed), education level (less than high school, high school, some college/2‑year degree, 4‑year college degree), self‑reported health status, income and sexual orientation. Three sexual‑orientation categories were created (heterosexual, gay/lesbian, bisexual); respondents answering “don’t know” or “not sure” were excluded (2.3%; n = 2,286). Analyses were weighted to account for NSDUH’s complex sampling design and poststratification. The authors used Rao–Scott tests for bivariate associations and multivariable logistic regression to estimate adjusted associations; survey year was included as a covariate. Multiple‑imputed variables provided by NSDUH were used where available to limit missing data. All analyses were conducted in Stata using survey commands and two‑tailed tests with significance set at P < 0.05.

In the pooled sample, men comprised 51.5% and women 48.5% of respondents. An estimated 9.68% of US adults (n = 17,602) reported lifetime psilocybin use. Survey year was associated with lifetime use in bivariate analyses (P < 0.0001), and 2018 showed a significant increase relative to 2015 in multivariable models. Bivariate tests indicated higher lifetime psilocybin prevalence among men, racial/ethnic minority respondents, those aged 26 years or older, bisexual individuals, respondents with higher education and income, those reporting less than “excellent” health, and people reporting lifetime use of other illicit drugs (all P < 0.0001). In adjusted logistic regression models, respondents in 2018 had slightly higher odds of reporting lifetime psilocybin use compared with 2015 (adjusted odds ratio [aOR] 1.11, 95% CI 1.01–1.22). Men had greater odds than women (aOR 1.90, 95% CI 1.77–2.04). Compared with ages 18–25, the 26–34 age group had higher odds (aOR 1.29, 95% CI 1.19–1.40), whereas those aged 35–49 (aOR 0.83, 95% CI 0.76–0.90) and 50+ (aOR 0.47, 95% CI 0.42–0.51) had lower odds. Sexual orientation was associated with psilocybin use: bisexual respondents had higher odds than heterosexuals (aOR 1.58, 95% CI 1.39–1.80); gay/lesbian respondents also reported substantial lifetime use in descriptive results (16.5% reported lifetime use). Relative to Non‑Hispanic White respondents, African Americans (aOR 0.21, 95% CI 0.17–0.25), Hispanics (aOR 0.61, 95% CI 0.54–0.68) and other/mixed‑race individuals (aOR 0.84, 95% CI 0.72–0.98) had lower adjusted odds of lifetime psilocybin use. Educational attainment was positively associated with psilocybin use: compared with less than high school, high school graduates (aOR 1.26, 95% CI 1.10–1.45), some college (aOR 1.79, 95% CI 1.56–2.04) and college graduates (aOR 2.43, 95% CI 2.11–2.81) had progressively higher odds. The extracted text reports adjusted odds ratios for self‑reported health status as 0.84 (95% CI 0.77–0.93) for “good” and 0.79 (95% CI 0.69–0.90) for “fair/poor” compared with “excellent”; the text also states these groups were "more likely" to use psilocybin, but the aORs numerically indicate lower odds (the extraction contains this inconsistency). No significant differences by income were reported. Lifetime use of other substances showed strong associations with psilocybin: marijuana (aOR 22.3, 95% CI 18.0–27.6), LSD (aOR 12.7, 95% CI 11.8–13.7), methamphetamine (aOR 1.71, 95% CI 1.55–1.89), cocaine (aOR 4.31, 95% CI 4.00–4.63) and heroin (aOR 1.57, 95% CI 1.36–1.80) were all associated with higher odds of reporting lifetime psilocybin use. The authors additionally note that among individuals reporting lifetime use of certain drugs, substantial proportions also reported psilocybin use: 64.5% of those who used LSD, 62.5% of heroin users, and 54.0% of methamphetamine users reportedly had also used psilocybin.

Yockey and colleagues interpret their findings as evidence that a non‑negligible share of US adults have tried psilocybin: roughly 9.68% reported lifetime use in the 2015–2018 pooled data. They observe a modest upward trend compared with earlier NSDUH estimates (8.5% in 2016; 8.8% in 2017) and identify 2018 as a year with a significant increase. The discussion situates these prevalence patterns within broader changes, including legislative shifts in some states and heightened clinical research interest, and suggests continued surveillance of temporal trends and recent‑use measures. The authors highlight consistent sociodemographic patterns: lower reported lifetime psilocybin use among several racial/ethnic minority groups compared with Non‑Hispanic White respondents, a positive association with educational attainment, and higher prevalence among sexual minorities—particularly bisexual individuals. They invoke minority‑stress frameworks as one possible explanation for elevated substance use among sexual minorities and suggest this may partly account for observed differences, while noting that motivations and contexts of use were not captured in NSDUH. Co‑use with other illicit substances was emphasised as a notable finding: lifetime marijuana use showed the strongest association (reported aOR ~22), and sizeable overlaps were observed between psilocybin and use of LSD, methamphetamine and heroin. The authors suggest these patterns have implications for harm reduction messaging and interventions that treat users with dignity and address polysubstance risks. Limitations acknowledged by the investigators include reliance on self‑report and potential recall bias, the restriction of NSDUH items to lifetime use only (no past‑year or past‑month measures for psilocybin, no frequency or reasons for use), and the absence of information on context of use. The authors conclude that the results can inform policy, prevention and harm‑reduction efforts and call for additional research on recent use patterns, motivations, and the relationships between psilocybin use and health disparities.