The association of psychedelic use and opioid use disorders among illicit users in the United States

Opioid abuse and dependence remain a major public health problem in the United States, with rising rates of illicit opioid use and substantial long-term harms including unemployment, crime, comorbidity and increased mortality. Conventional maintenance treatments such as methadone and buprenorphine reduce illicit use and improve retention but have limitations including side effects, logistical burdens and incomplete long‑term effectiveness; psychosocial interventions alone are also insufficient. In parallel, serotonergic dysfunction has been implicated in opioid disorders, and earlier clinical and observational studies have reported promising signals for classic psychedelics (for example LSD, psilocybin, ayahuasca) in treating various substance use disorders and improving psychological outcomes, though most work has been small, local and uncontrolled. Pisano and colleagues set out to examine whether a history of classic psychedelic use is associated with reduced risk of past‑year opioid abuse and dependence within a nationally representative sample of illicit opioid users. Using data from multiple years of the National Survey on Drug Use and Health (NSDUH), the study aimed to test the primary hypothesis that lifetime use of classic psychedelics would be linked to lower odds of meeting DSM‑IV criteria for past‑year opioid abuse or dependence; a secondary analysis explored associations between psychedelic history and each of the individual DSM‑IV dependence criteria.

Data came from the NSDUH, an annual, in‑person, nationally representative survey of non‑institutionalised civilians 12 years or older; the investigators pooled six survey years (2008–2013). The analytic sample was restricted to adults aged 18 or older who reported lifetime illicit opioid use, defined as lifetime use of recreational pain killers or heroin. The study received institutional approvals noted in the extracted text. A binary exposure variable (LIFEHAL) indicated lifetime use of classic psychedelics: LSD, mescaline, psilocybin, peyote, San Pedro cactus, N,N‑dimethyltryptamine or N,N‑diethyltryptamine, and ayahuasca. The authors excluded substances they did not classify as classic psychedelics, including MDMA, designer tryptamines/phenethylamines, Salvia divinorum and dissociative agents such as ketamine and ibogaine. Primary outcomes were meeting DSM‑IV criteria for past‑year abuse or dependence for prescription pain killers and for heroin, as operationalised by NSDUH variables. Dependence was defined as endorsement of three or more of the survey’s 10 dependence criteria (for example: spending a lot of time obtaining/using, inability to cut down, tolerance/withdrawal, continued use despite problems). Multivariate logistic regression models tested associations between classic psychedelic history and the outcomes while adjusting for demographic covariates (age, race/ethnicity, education, income, sex, marital status, self‑reported propensity for risky behaviour) and lifetime use of other substances (marijuana, stimulants, tranquilizers, inhalants, ecstasy, phencyclidine, sedatives and cocaine). Analyses were conducted in Stata 14 with survey commands (svyset) to account for the complex sampling design and sampling weights. The extracted text does not report additional modelling details such as handling of missing data or model diagnostics.

Across 228,556 adult NSDUH respondents, 44,678 (15.0% weighted) reported lifetime illicit use of prescription pain killers or heroin; among these illicit opioid users, 18,517 (44.7% weighted) reported lifetime use of classic psychedelics. The extracted text indicates that classic psychedelic use was more concentrated among White respondents, males and those reporting greater engagement in risky behaviours, and that most psychedelic users had also used marijuana or cocaine. Within the illicit opioid user subgroup, 630 respondents met past‑year abuse criteria (1.2% weighted) and 2,571 met past‑year dependence criteria (4.3% weighted). In multivariate models, lifetime classic psychedelic use was associated with a reduced risk of past‑year opioid dependence (weighted risk ratio (RR) = 0.73, 95% CI 0.60–0.89, p = 0.002). A similar association was observed for past‑year opioid abuse (weighted RR = 0.60, 95% CI 0.41–0.86, p = 0.006). No other illicit substances showed associations with decreased risk of past‑year dependence; however, lifetime marijuana use was associated with reduced risk of past‑year opioid abuse (weighted RR = 0.45, 95% CI 0.30–0.66, p < 0.001) but was not significantly associated with dependence. The authors report effect‑size comparisons showing that the association of psychedelic history with dependence was of similar magnitude to that of higher education (education RR = 0.71), and that age and income had smaller protective associations for dependence (age RR = 0.85; income RR = 0.91). For abuse, psychedelic use had a slightly larger effect than education (education RR = 0.66) and income (income RR = 0.81), while age was not significantly associated with abuse. In secondary analyses of the 10 DSM‑IV dependence criteria, psychedelic history was linked to significantly lower risk on seven criteria (RRs ranging approximately from 0.65 to 0.78); the three criteria not associated with psychedelic history were ‘‘continued use despite physical issues,’’ ‘‘spent time getting over effects’’ and ‘‘usual use has less effect.’’ The extracted text references tables and figures for detailed rates and model coefficients but these specific tables/figures were not provided in the extraction.

Pisano and colleagues interpret their findings as consistent with the hypothesis that lifetime use of classic psychedelics is associated with lower likelihood of past‑year opioid abuse and dependence among people with a history of illicit opioid use. They emphasise that the associations were present in a large, nationally representative dataset and that, apart from marijuana, other illicit drugs were generally associated with increased risk rather than reduced risk. The authors propose several possible mechanisms that might underlie the observed associations. At a neurobiological level, classic psychedelics act primarily at serotonin 5‑HT2A receptors; repeated psychedelic exposure produces rapid downregulation/desensitisation of these receptors, and the investigators suggest this could reduce stress‑related relapse given links between frontolimbic 5‑HT2A binding, anxiety and exaggerated stress responses. Psychedelics may also have anti‑nociceptive effects that could reduce opioid use for pain. Psychologically, psychedelics administered within or outside therapeutic settings can produce an ‘‘afterglow’’ period of improved mood, insight and reduced guilt, which the authors posit could facilitate behaviour change and support abstinence initiated during psychotherapeutic work. The authors acknowledge important limitations. NSDUH data are self‑reported and subject to recall and reporting bias; the survey excludes institutionalised populations (for example, active military, those in hospitals, treatment centres or prisons), which may affect generalisability and undercount less common drug use. Crucially, the cross‑sectional design precludes causal inference: it is not possible to determine whether psychedelic use reduces opioid misuse, whether people less prone to opioid problems are more likely to use psychedelics, or whether unmeasured factors (for example spirituality, personality traits or other sociodemographic variables) account for the associations. Safety concerns are noted as well: psychedelics can precipitate adverse psychological events, including psychosis in a susceptible minority, and the mechanisms of any protective effect remain speculative. The authors conclude that, while causality cannot be inferred from these data, the findings add to a growing body of evidence linking classic psychedelic use with positive psychological characteristics and with signals of potential utility in treating substance use disorders, thereby supporting the rationale for further controlled clinical research.