Psychedelic mushrooms in the USA: Knowledge, patterns of use and association with health outcomes

Psychedelics, particularly psilocybin-containing mushrooms, have received renewed scientific and public attention over the past decade owing to emerging clinical trials and media coverage that portray therapeutic potential for conditions such as depression, post-traumatic stress disorder and addiction. Regulatory changes in some US jurisdictions, growing investment in psychedelic biotechnology and prominent popular media portrayals have increased public exposure to favourable narratives about psychedelics. At the same time, population surveys indicate rising hallucinogen use, but routine national surveillance groups diverse substances together and provides limited detail on specific use patterns for psilocybin-containing psychedelic mushrooms (PM). Morlock and colleagues set out to characterise knowledge about and recent use of PMs among US adults, and to examine associations between PM use and measures of health status, health-related quality of life and self-reported mental health. The study aimed to compare socio-demographic characteristics of past-year PM users with non-psychedelic users and to assess whether contemporaneous events—specifically the COVID-19 pandemic and the 2020 US election—were associated with changes in PM use patterns.

The investigators used an online cross-sectional survey fielded monthly between November 2020 and March 2021 to recruit US adults aged 18 years or older. A random stratified sampling framework was applied to achieve a demographic composition representative of the US adult population by region, gender, age and race, with fieldings targeting about 1,000–2,000 respondents per month. Analysis weights were applied to reflect census distributions and a Taylor Series Linearization method accounted for complex survey design. Quality-control measures included digital fingerprinting to reduce fraudulent responses. Survey items captured demographics, education, estimated median household income (derived from participants' zip-code census data), self-reported comorbidities (summarised using the Charlson Comorbidity Index, a tool that estimates 10-year survival risk from multiple comorbid conditions), health-related quality of life (VR-12 providing physical and mental component summaries and a VR-6D utility), anxiety (GAD-7), and depression (PHQ-9). Participants reported psychedelic use in the past 12 months, knowledge about positive reporting of psychedelics, reasons for use, and healthcare utilisation following use. For comparative analyses, participants who had used other psychedelics or combined PMs with other psychedelics were excluded to isolate exclusive PM users. Analyses compared PM users with participants reporting no psychedelic use in the past 12 months. An unweighted multivariate logistic regression model predicting past-year psilocybin use adjusted for sex, age, race, region, education, employment, Charlson Comorbidity Index score, GAD-7, PHQ-9 and health insurance status; odds ratios with 95% confidence intervals were reported. The survey was judged Institutional Review Board-exempt because responses were anonymised; respondents received modest panel-based incentives for completion.

The final sample comprised 7,139 respondents, representing an 83.8% response rate. In the unweighted data, 526 participants (7.4%) reported past-year psychedelic use; this included 134 participants (3.8%) who used PMs plus other psychedelics and 122 participants (3.6%) who used PMs exclusively. Weighted to the US adult population, 7.1% of adults (estimated 17,862,102; 95% CI: 6.5–7.7) reported past-year psychedelic use, of whom approximately half (49.2%, or an estimated 8,780,328 adults; 95% CI: 44.7–53.6) were PM users. The investigators compared an estimated 4,121,102 adults (1.7%, 95% CI: 1.4–2.1) who used only PMs with 233,435,392 adults (98.3%, 95% CI: 97.9–98.6) who reported no psychedelic use in the prior 12 months. PM users differed from non-users on a range of health indicators. The extracted text reports that PM users were less likely to be overweight than non-users, but they reported higher prevalence of several comorbid conditions including depression, anxiety, migraine and insomnia. Standardised measures indicated poorer mental-health-related quality of life among PM users: VR-12 mental component scores were lower (39.5 vs 45.5) and VR-6D health-utility values were lower (0.63 vs 0.69). Symptom scores were higher for anxiety (GAD-7 mean 9.6 vs 5.9) and depression (PHQ-9 mean 11.2 vs 6.8) among PM users compared with non-users. PM users also reported greater healthcare utilisation: urgent care visits (20.8% vs 9.9%) and hospitalisation (9.2% vs 3.9%) were more frequent. Attitudes and motivations differed markedly: PM users were substantially more likely than non-users to endorse positive potential for PMs across a range of conditions, for example general mental health and well-being (65.8% vs 15.8%), managing diagnosed psychiatric conditions (50.9% vs 16.6%) and self-diagnosed psychiatric issues (34.7% vs 7.6%). Reported reasons for PM use were primarily general mental health and well-being (63.6%), followed by treating diagnosed psychiatric conditions (31.8%) and self-diagnosed conditions (19.0%). The survey also captured a perceived increase in positive reporting about psychedelic drugs in the prior six months, with mean scores reported for users and non-users (means 2.06 vs 3.56), although the extracted text contains inconsistencies in the Likert-scale labelling. Frequency of PM use was not reported to have changed in relation to either COVID-19 or election politics. Finally, 17.9% of PM users reported medical treatment following use. In multivariate logistic regression, the authors report that associations between PM use and anxiety or depression were not statistically significant; however, PM use remained associated with greater comorbidity burden and lower likelihood of having health insurance (specific regression coefficients and full model statistics are not fully reported in the extracted text).

Morlock and colleagues interpret their findings as evidence that PMs are widely known and used among US adults, with estimated past-year psychedelic use and PM use substantially higher than recent national survey estimates such as NSDUH. The authors suggest that the higher prevalence observed in their online, anonymised survey may reflect reduced reporting bias compared with household interview surveys and point to growing public exposure to positive messaging about psychedelics as a contributing factor. Despite the positive reputation of psilocybin and PMs, the researchers found associations between past-year PM use and worse mental-health indicators, higher comorbidity burden, greater healthcare utilisation and a lower likelihood of having health insurance. They note a discrepancy between these observed associations and the predominantly positive narrative in media and some clinical research. The discussion contrasts the present findings with an international study that reported lower psychological stress among regular psychedelic users, proposing that differences may arise because the present study captured any past-year use (not regular use) and because US PM users may represent a different demographic profile than international samples. The authors emphasise several areas of uncertainty and caution. They call for more evidence on dosing, duration of therapeutic effects, and potential adverse outcomes including interactions with dopamine systems; they also flag the emergence of novel psychedelics that may carry distinct risks. Methodological limitations acknowledged include reliance on self-report, inclusion of only internet-accessible respondents, exclusion of combined psychedelic users (which may have omitted experienced poly-drug users), lack of multiple-comparison alpha adjustment, and the unusual study timing during the COVID-19 pandemic which may limit generalisability. The authors present the use of recent (rather than lifetime) reports as a strength for public-health relevance and argue that population-level monitoring can inform pragmatic trial design and harm-reduction efforts. Policy and research implications discussed by the authors include the need for evidence-based regulation and harm-reduction strategies, development of guidelines to optimise therapeutic use, and regularised population surveys to track trends and drivers of use. They also recommend separate analyses of other psychedelics used exclusively or in combination to better characterise potential benefits and harms.

The authors conclude that population-based surveillance provides useful insight into entheogen use patterns and that PMs remain particularly popular. Although lifetime use of PMs is often portrayed as protective in prior literature, this study found associations between recent PM use and adverse physiological and mental-health indicators. Morlock and colleagues call for development of guidelines to optimise therapeutic applications, ongoing population-level monitoring to track changes over time, additional modules to identify drivers of use and misuse for different entheogens, and separate analyses of exclusive and combined psychedelic use.