Over 30 million psychedelic users in the United States

Introduction

The classical serotonergic psychedelics, LSD (lysergic acid diethylamide), psilocybin (“magic mushrooms”), and mescaline (peyote and other cacti), have their main mechanism of action at the serotonin 2A receptor (5-HT_2A), produce similar, often indistinguishable subjective effects, and elicit cross-tolerance^1,2. The mechanisms of action, subjective effects, and risk profile of the classical serotonergic psychedelics distinguishes them from other drugs sometimes also labeled “hallucinogens”, such as entactogens, like methylenedioxymethamphetamine (MDMA; ecstasy) that act primarily at serotonin transporters, or dissociative anesthetics, like phencyclidine (PCP) or ketamine that act primarily at NMDA glutamate receptors¹.

Prevalence data on psychedelic use in the US is often reported for LSD alone (ignoring psilocybin and mescaline), or for psychedelics grouped together with PCP (popular in the 1970s), MDMA (popular since the 1990s), and/or other “hallucinogens” (some older estimates of hallucinogen use even included cannabis, amphetamine, and cocaine as hallucinogenic drugs), or for use among teenagers but not adults. Here, we present estimated lifetime prevalence of psychedelic use by age category using data from a large US population survey.

Methods

We examined the estimated lifetime use of psychedelics by age based on 2010 data of the National Survey on Drug Use and Health (NSDUH). Results are presented for males and females separately. We counted participants as having any lifetime psychedelic use if they reported ever using LSD, psilocybin, mescaline, or peyote. The use of mescaline and peyote were combined into one category because mescaline is the active substance of the peyote cactus, but peyote use was also examined separately. Current age was only available as a categorical variable. This study was exempt from review by our Regional Committee for Medical Research Ethics because all data are available in the public domain without any identification of personal information.

Results

An estimated 32 million (95% confidence interval (CI): 30 to 33 million) US residents in 2010 reported lifetime use of LSD (23 million, 95% CI: 22 to 25 million), psilocybin (21 million, 95% CI: 20 to 22 million), mescaline (11 million, 95% CI: 10 to 12 million), or peyote (6 million, 95% CI: 5 to 7 million).

Figure 1 shows the rate of lifetime psychedelic use in the US in 2010 by age category and gender. Lifetime rate of psychedelic use among people aged 50 to 64 years (the “baby boomer” generation) was similar to the rate among people aged 21 to 49 years. Among people aged 21 to 64 years, 17%, (95% CI: 15% to 18%) reported ever using LSD, psilocybin, or mescaline, including 22% (95% CI: 21% to 23%) of males and 12% (11% to 13%) of females. Prevalence of psychedelic use was low among people aged 65 and older (total 1.3%, 95% CI: 0.8% to 2.1%). Rate of lifetime psychedelic use was greatest among people aged 30 to 34 years (total 20%, 95% CI: 18% to 22%), with 26% (95% CI: 23% to 29%) of males and 15% (95% CI: 13% to 17%) of females.

Figure 1. Lifetime psychedelic use by age and gender in the US in 2010.

Error bars show 95% confidence intervals. Any psychedelic includes LSD, psilocybin, mescaline, and/or peyote. Mescaline includes both mescaline and peyote.

Discussion

Psychedelics continue to be widely used in the US. Common reasons given for using psychedelics include curiosity, mystical experiences, and introspection³. Rates of lifetime psychedelic use are greater in males than in females. Overall rates of lifetime psychedelic use are roughly the same among the “baby boomers” and younger adults. However, psilocybin was more common among younger adults, while LSD and mescaline or peyote were more common among older adults. Use of psilocybin mushrooms has increased since the 1970s in the US and worldwide, likely due to dissemination of simple home cultivation techniques, instructions on finding wild mushrooms, and information about effects and methods of psilocybin mushroom use⁴. This was a retrospective cross-sectional study. Self-reports of drug use behaviors could be influenced by memory errors and under-reporting; however, a 14-year longitudinal study reported good consistency over time in the reporting of lifetime LSD use⁵.