Who Keeps Using Lysergic Acid Diethylamide? Correlates of Past-Year Use in People Who Initiated Use at least Five Years Ago

Abstract

Introduction:

Little is known about the correlates of repeated non-medical lysergic acid diethylamide (LSD) use. Therefore, we aimed to determine the prevalence and correlates of past-year LSD use among people aged 18 years and older in the United States who first used LSD at least 5 years ago.

Materials and Methods:

Using data from the 2015–2019 National Survey on Drug Use and Health, we examined the estimated weighted prevalence of past-year LSD use and explored potential demographic, psychosocial, and drug use correlates using univariable and multivariable modeling.

Results:

Among US adults who had initiated LSD use at least 5 years ago, 4.2% were estimated to have used LSD in the past year. Estimated past-year LSD use prevalence decreased with time since first use, dropping from 14.4% among those who first used LSD 5 years ago to 0.1% among those who first used LSD 46–50 years ago. On multivariable analysis, past-year LSD use was positively associated with being male, never having been married, living in poverty, having a higher level of education, lifetime stimulant use, being approached by a drug seller in the past 30 days, having ever sold illegal drugs, perceiving LSD as lower risk, perceiving LSD as more available, and having attempted suicide in the past year. Past-year LSD use was negatively associated with having children in the home, living in a small metropolitan area, and years since LSD use initiation.

Conclusions:

Past-year LSD use is infrequent among lifetime LSD users and appears to decline with time since the initiation of LSD use. Perceived risk (lower) and perceived availability (higher) of LSD were the factors associated with the largest adjusted odds ratios for past-year LSD use. Further research is needed to understand the infrequency of LSD use among lifetime LSD users and its public health implications.

Introduction

Despite decreasing perceived risk and increasing use of lysergic acid diethylamide (LSD) in the United States in recent years,^1–3 as well as growing industry interest in developing LSD and other psychedelics as medicines, ⁴ relatively little research has explored LSD use patterns or characteristics of repeat LSD users. Due to several factors such as rapid tachyphylaxis,^5–7 unpredictability of subjective effects, ⁸ limited dopaminergic stimulation, ⁹ and serotonin 2C receptor partial agonism, ¹⁰ LSD and other classical psychedelics are not typically associated with compulsive use. However, having a better understanding of repeat users of LSD and other psychedelics could yield insights into why some observational studies report potential benefits of naturalistic psychedelic use, and others report harms. ¹¹

Surprisingly little is known about basic aspects of psychedelic use, such as the average number of lifetime psychedelic use episodes and frequency of use over intervals of interest (e.g., past month or year). However, in recent years, some relevant data on this topic have emerged. For example, in a 2013 survey of college students in upstate New York, the mean number of lifetime psilocybin mushroom use episodes among users was 3.4, with 37% of users reporting only one use. ¹² More recently, a 2024 survey of 400 Swedish psychedelic users (predominantly male, with an average age of 35) reported an average of seven lifetime psychedelic experiences. ¹³ Importantly, since these surveys did not utilize representative random samples from the broader population of psychedelic users, the generalizability of their findings is unclear. Recently published data from the RAND Psychedelic Survey, which employed a nationally representative sampling of the US population, revealed that the frequency of repeat psilocybin use is low. ¹⁴ Among past-year psilocybin users who did not use psilocybin in the past month (2.2% of total respondents), 58% reported using psilocybin only one or two days in the past year. Among past-month psilocybin users (0.9% of total respondents), the mean number of days of psilocybin use in the last month was 4.6. Unfortunately, this survey did not provide data for LSD use, and it is uncertain whether these psilocybin data can be generalized to LSD use given the differences between LSD and psilocybin.

Limited understanding also exists regarding the long-term effects of repeated LSD use. Rodent studies suggest repeated LSD use may enhance prosocial behaviors, though it is not known whether this is also true for humans. ¹⁵ A higher number of LSD use episodes is associated with higher prevalence of LSD-like recurrences (“flashbacks”) in humans. ¹⁶ LSD users may also differ from each other in terms of personality based on their frequency of use, ¹⁷ though it is unclear whether such differences are premorbid and, if they are, what role they may play in long-term sequelae of use. In research settings, LSD appears to enhance aspects of personality such as optimism and openness for 2 weeks post-treatment, while evidence is mixed for longer-term personality changes.^18,19 These findings suggest the previously identified personality differences in LSD users based on use frequency may be premorbid, which might at least partially explain the heightened risk of flashbacks observed in more frequent LSD users.

While large, nationally representative surveys on substance use, such as the US National Survey on Drug Use and Health (NSDUH), report data on the use of LSD and other psychedelics, they do not query participants on the number of lifetime uses for psychedelics or frequency of use, making detailed epidemiological investigation of this area challenging. ²⁰ However, the NSDUH does collect the date of first use for LSD, as well as whether participants used LSD in the past year, allowing some probing of repeat LSD use. Two questions of interest that can be investigated for participants who first used LSD at least a year prior to their participation in the NSDUH are: What proportion have used LSD within the past year? And, how do past-year LSD users in this cohort differ from those who have not used LSD in the past year?

With this in mind, we sought to determine the prevalence and correlates of past-year LSD use among people who first used LSD at least 5 years prior to NSDUH participation. We chose to focus on this group of LSD users since it might provide more useful insights from a clinical and public health standpoint than investigating users who initiated use at least 1 year prior to NSDUH participation.

Methods

Data description

Data were sourced from the 2015–2019 administrations of the NSDUH. The NSDUH is conducted annually by the US Substance Abuse and Mental Health Services Administration (SAMHSA), part of the US Department of Health and Human Services, across all 50 states and the District of Columbia. ²¹ The survey is administered in person to a nationally representative sample of noninstitutionalized civilians, excluding populations such as individuals who are incarcerated, hospitalized, or residing in nursing homes. It collects information on tobacco, alcohol, and other drug use; mental health; related health behaviors; and treatment received for mental health and substance use disorders. To enhance the accuracy of self-reports on sensitive topics, the NSDUH employs audio computer-assisted self-interviewing (ACASI). A sample-weighted design is applied to ensure the results reflect the broader US population, incorporating adjustments for demographic characteristics, non-response, and other factors. ²²

Although 2020 NSDUH data were available, data collection was disrupted for that sample due to COVID-19, and comparing data from 2020 to NSDUH data from other years is not advisable. ²³ We chose to focus our investigation on adults aged 18 and older at the time of survey participation.

Statistical analysis

The primary outcome was past-year LSD use. This is an imputed variable in the NSDUH data set, and therefore, there were no missing data for this variable. Unweighted counts (Ns) by past-year LSD use are reported, but unweighted counts for individual variables are not reported, consistent with other published analyses of NSDUH data. Continuous factors are summarized as weighted medians and interquartile ranges, and descriptive comparisons were evaluated with log-transformed linear regression. Categorical factors are summarized using weighted percentages and 95% confidence intervals, and comparisons between availability responses were evaluated using Rao-Scott Chi-square tests. Although the Rao-Scott Chi-Square test does not impose a strict minimum cell count requirement, given concerns about potential instability from sparse cells, we conducted a sensitivity analysis excluding categories with observed counts <5; the results remained consistent with the full analysis, indicating robustness of the findings. ²⁴ Univariable associations were adjusted for survey year, age, employment, education, race, metropolitan area, and religious importance.

Survey-weighted logistic regression models were constructed to calculate adjusted odds ratios to estimate odds ratios for past-year LSD use among lifetime LSD users initiating use at least 5 years prior to NSDUH participation. Univariate tests for association informed the construction of the multivariable model. Models were simplified where appropriate to reduce complexity and to address multicollinearity and confounding. All odds ratios were adjusted for survey year (2015–2019), age group (18–25, 26–34, 35–49, and 50+), gender (male and female), education (high school but no diploma, high school diploma/GED, some college/no degree, 2-year degree, and 4-year degree), employment status (full-time, part-time, unemployed, and other), marital status (never married, married, divorced, and widowed), ethnicity/race (White, Black, Asian, Hispanic, and other), urbanicity (small, large, and non), and criminal arrest history (yes/no). Many of these factors have been identified as correlates of past-year LSD use within the general US population. ¹

Survey analysis procedures were used due to the complex survey design, utilizing the NSDUH respondent weight, replicate, and variance strata. Since this study utilizes 5 years of survey data, the respondent weight was divided by five for analyses that included all study years. All reported prevalence estimates and percentages are weighted using NSDUH respondent weights to provide population-level estimates. Significance was assessed at p < 0.05. Analysis was conducted in SAS 9.4 (SAS Institute, Cary, NC). SAS survey procedures were used for all analyses.

For more details about statistical model construction, see the Appendix in the Supplementary Data.

Results

Description of the cohort of respondents who first used LSD at least 5 years ago

An unweighted total of 17,280 adult respondents reported having first used LSD at least 5 years prior to their participation in the NSDUH. All reported prevalence estimates that follow are weighted to reflect the US population. Among this estimated population, 33.7% were between the ages of 35 and 49 years, and 48.9% were 50 years or older. 62.7% were male, 84.1% were Non-Hispanic White, 48.2% were married, and 40.8% reported a family income of $75,000 or greater. 31.0% had at least a four-year college degree, and 57.0% were employed full time. 17.6% reported past-year serious psychological distress, and 0.81% reported a past-year suicide attempt.

Estimated lifetime prevalence of non-psychedelic drug use in this population was high: 99.3% for alcohol, 98.7% for marijuana, 96.0% for tobacco, 76.2% for cocaine, 43.7% for inhalants, 38.4% for methamphetamine, 35.3% for pain reliever misuse, 19.2% for tranquilizer misuse, 16.4% for stimulant misuse, 15.1% for heroin, and 12.0% for sedative misuse. An estimated 12.9% had ever used a needle to inject drugs.

Estimated lifetime use of other psychedelics included: 64.2% for psilocybin mushrooms, 39.0% for 3,4-methylenedioxymethamphetamine (MDMA), 28.1% for mescaline, 21.1% for phencyclidine (PCP), 20.2% for peyote, and 10.5% for ketamine. An estimated 0.34% met criteria for past-year hallucinogen dependence based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth edition (DSM-IV).

The median estimated number of years since first LSD use was 17.6 (interquartile range: 15.8, 20.1). Estimated perceived risk of trying LSD was 11.4% for “no risk,” 29.0% for “slight risk,” 22.4% for “moderate risk,” 36.9% for “great risk,” and 0.34% for “don’t know.” Estimated perceived difficulty of obtaining LSD was 27.7% for “probably impossible,” 29.0% for “very difficult,” 24.2% for “fairly difficult,” 12.3% for “fairly easy,” 5.1% for “very easy,” and 1.7% for “don’t know.” For further details on the characteristics of respondents, see Supplementary Table S1.

Prevalence of past-year LSD use in relationship to number of years since first LSD use

Among the estimated population of individuals who first used LSD at least 5 years prior to survey participation, 4.2% were estimated to have used LSD in the past year. As the number of years since first LSD use increased, the estimated prevalence of past-year LSD uses generally decreased. The highest estimated prevalence of past-year use was found among people who had first used LSD 5 years ago (14.4%), while the lowest was among people who had first used LSD 46–50 years ago (0.1%). Large drops in estimated past-year LSD use were observed between cohorts whose first use was 6–10 years and 11–15 years pre-survey (from 14.4% to 6.0%), and between 11–15 years and 16–20 years pre-survey (from 6.0% to 1.9%). For further details, see Table 1.

Table 1.

Weighted Prevalence and Corresponding Unweighted Counts of Respondents for Past-Year LSD Use According to Years Since First LSD Use

Years since first LSD use	Past-year LSD use unweighted N (weighted %)
	No	Yes	Total N
5	688 (85.6)	116 (14.4)	804
6–10	2095 (85.7)	351 (14.3)	2446
11–15	1586 (94)	102 (6)	1688
16–20	2602 (98.1)	50 (1.9)	2652
21–25	2572 (98.1)	49 (1.9)	2621
26–30	2103 (98.5)	32 (1.5)	2135
31–35	1400 (99.2)	11 (0.8)	1411
36–40	1247 (99.5)	6 (0.5)	1253
41–45	1287 (99.8)	2 (0.2)	1289
46–50	864 (99.9)	1 (0.1)	865
51+	115 (99.1)	1 (0.9)	116
Total	16559 (95.8)	721 (4.2)	17280

LSD, lysergic acid diethylamide.

Table 2 gives the estimated prevalence of past-year LSD use relative to the number of years since first LSD use within different age cohorts. While some of the highest estimated prevalences of past-year LSD use occurred in participants 18–34 years old who had first used LSD 5–10 years prior to NSDUH participation, among respondents 35–49 years old, none who reported initiating LSD use 5 years prior to NSDUH participation reported past-year LSD use. Among unweighted respondents aged 50 years and older, none reported initiating LSD use 5 years prior to NSDUH participation, and none who reported initiating use 6–10 years prior to NSDUH participation reported past-year LSD use.

Table 2.

Weighted Prevalence and Corresponding Unweighted Counts of Respondents for Past-Year LSD Use According to Number of Years Since First LSD Use Within Different Age Groups

Respondent age group	Years since first LSD use	Past-year LSD use unweighted N (weighted %)
		No	Yes	Total
Age 18–25	5	517 (84.5)	95 (15.5)	612
	6–10	878 (80.9)	207 (19.1)	1085
	11–15	26 (78.8)	7 (21.2)	33
	16–20	4 (100)	0	4
	21–25	1 (50)	1 (50)	2
	26+	0	0	0
	Total	1426 (82.1)	310 (17.9)	1736
Age 26–34	5	159 (88.3)	21 (11.7)	180
	6–10	1115 (89)	138 (11)	1253
	11–15	1185 (93.4)	84 (6.6)	1269
	16–20	751 (96.5)	27 (3.5)	778
	21–25	21 (95.5)	1 (4.5)	22
	26–30	2 (100)	0	2
	31+	0	0	0
	Total	3233 (92.3)	271 (7.7)	3504
Age 35–49	5	12 (100)	0	12
	6–10	95 (94.1)	6 (5.9)	101
	11–15	369 (97.4)	10 (2.6)	379
	16–20	1824 (98.8)	23 (1.2)	1847
	21–25	2493 (98.1)	47 (1.9)	2540
	26–30	1865 (98.4)	30 (1.6)	1895
	31–35	634 (98.9)	7 (1.1)	641
	36–40	23 (100)	0	23
	41–45	1 (100)	0	1
	46–50	1 (100)	0	1
	51+	0	0	0
	Total	7317 (98.3)	123 (1.7)	7440
Age 50+	5	0	0	0
	6–10	7 (100)	0 (0)	7
	11–15	6 (85.7)	1 (14.3)	7
	16–20	23 (100)	0 (0)	23
	21–25	57 (100)	0 (0)	57
	26–30	236 (99.2)	2 (0.8)	238
	31–35	766 (99.5)	4 (0.5)	770
	36–40	1224 (99.5)	6 (0.5)	1230
	41–45	1286 (99.8)	2 (0.2)	1288
	46–50	863 (99.9)	1 (0.1)	864
	51+	115 (99.1)	1 (0.9)	116
	Total	4583 (99.6)	17 (0.4)	4600

LSD, lysergic acid diethylamide.

Correlates of past-year LSD use among people who first used LSD at least 5 years ago

For results of univariable tests of associations between characteristics and past-year LSD use, see Supplementary Table S1. On multivariable modeling, the following respondent characteristics were positively associated with past-year LSD use: education level, male gender, never having been married, living in poverty, lifetime stimulant use, being approached by a drug seller in the past 30 days, having ever sold illegal drugs, perceived availability of LSD, and past-year suicide attempt. The following characteristics were negatively associated with past-year LSD use: a child in the home, living in a small metropolitan area, perceived risk of LSD use, and number of years since first LSD use. For further details, see Figure 1.

Fig. 1.

Forest plot of factors investigated for potential association with past-year LSD use among people who initiated LSD use at least 5 years prior to NSDUH administration.

Discussion

To our knowledge, this is the first investigation of repeated LSD use utilizing contemporaneous data from a nationally representative US survey. Our findings provide potentially valuable information about the misuse potential of LSD. The population identified here overlaps with study populations described in the FDA guidance for industry on investigations of human abuse potential in that its members are generally experienced recreational drug users with experiences across multiple substance classes. ²⁵ While these epidemiological findings lack information on drug liking and LSD-associated adverse events, they do illuminate certain factors that may influence ongoing LSD use.

Our primary finding is that past-year LSD use is uncommon among individuals who initiated LSD use 5 or more years ago, with the likelihood of past-year use decreasing as time since first use increases. Specifically, estimated past-year LSD use prevalence among those whose first LSD use was 11–16 years ago (6.0%) was less than half that of those who initiated use 5–10 years ago (14.4%). For those who initiated LSD use 16–20 years ago, fewer than two percent were estimated to have used LSD again in the past year. When time since initiation of LSD use was analyzed as a continuous variable in a multivariable model, the odds of past-year LSD use decreased by 7% with each additional year since first use within this group. Our finding of higher odds of past-year LSD use among people in poverty suggests that cost is not an important factor in repeat LSD use. This is consistent with reports that a 100–150 mcg dose of LSD can cost as little as $10 in the US. ²⁶

Lower perceived risk and higher perceived availability of LSD were associated with the highest odds ratios for past-year LSD use in our multivariable model, consistent with other studies using NSDUH data. ² These were followed in magnitude by past-year suicide attempt. Possible explanations for the latter finding include the possibility that LSD might precipitate suicidal ideation and/or attempts during or soon after use^27,28 or that suicidal individuals may be more likely to use LSD—possibly to self-treat depression or other psychiatric conditions. Of note, LSD use is rising more quickly in people with depression than in the general population. ²⁹ In the 2020 Global Drug Survey, 14% of respondents reported self-treatment of “a psychiatric condition or a specific worry” with psychedelics in the past year, with LSD being the most commonly used psychedelic for this purpose (56% of self-treating respondents). ³⁰ LSD was also reported to be the substance most helpful for self-treatment (35%). However, among respondents who had used both psilocybin mushrooms and LSD for self-treatment, psilocybin was slightly preferred over LSD (40.7% vs. 40.0%). Compared to psilocybin, LSD was also associated with more negative outcomes during self-treatment. Another potential explanation for the association between past-year suicide attempt and past-year LSD use is the finding that LSD users are less likely to receive mental healthcare. ³¹ Given the NSDUH’s data collection methods, we could not determine the direction of the temporal relationship between past-year suicide attempt and past-year LSD use. This relationship, therefore, requires further study.

Several factors positively associated with past-year LSD use in this group of lifetime LSD users have also been identified in multivariable models as being positively associated with past-year LSD use in the general US population: male gender, never having been married, living in poverty, lifetime stimulant use, being approached by a drug seller in the past 30 days, lower perceived risk of LSD, increase perceived availability of LSD, and past-year suicide attempt. ¹ Similarly, having a child in the home was negatively associated with past-year LSD in this cohort and the general US population. However, a higher educational level was positively associated with past-year LSD use in this cohort, but not in the US population in general. Additionally, this cohort did not exhibit a previously identified positive association between past-year LSD use and identifying as Non-Hispanic Asian in the general US population and a negative association between past-year LSD use and age. In the RAND Psychedelic Survey, among lifetime psilocybin users who had not used in the past year, 43% of 18–25 year olds had used psilocybin 1–2 years ago compared to 20% among respondents older than 60 (66% of whom had last used psilocybin 10 or more years ago). ¹⁴ Controlling for time since initiation of LSD use in this cohort may explain the observed discrepancies for age as a predictor of past-year LSD use. The association between living in a small metropolitan area and having decreased odds of past-year LSD use observed in this cohort was also not present in a previous study of the US general population. ¹

Taken together, these findings suggest that correlates of past-year LSD use among the US general population and Americans who initiated LSD at least 5 years ago are largely similar, though the prevalence of past-year LSD use is significantly lower in the former group (0.59–0.87% from 2015 to 2019) ¹ compared to the latter (4.2% on average over this period). Important drivers of this difference appear to be a much lower perceived risk of LSD use in this cohort than in the general US population (prevalence of view that there is “no risk” in trying LSD: 11.4% vs. 3.5%, respectively) and a much higher perceived availability of LSD (prevalence of view that it is “probably impossible” to obtain LSD: 27.7% vs. 41.0%, respectively). ¹

Perhaps the most intriguing questions brought up by these findings are why repeat LSD use appears to be so infrequent. It would be helpful to survey LSD users to better understand factors influencing the frequency of use and the decision to stop using LSD completely. Given the high prevalence of other psychedelic use within this cohort, one possibility is that switching to other psychedelics could reduce LSD use frequency. Another possible contributor to the low frequency of repeat LSD use observed is the loss of novelty of experience for some LSD users. Previous research shows that more experienced ayahuasca users may develop compensatory mechanisms for the acute impairing effects of ayahuasca on cognitive processes, which could also be the case for LSD users. ³² Whether some first-time LSD users might find the psychedelic experience too unpleasant or uninteresting to repeat should also be investigated. Though we are unaware of data on the desire to use LSD again in non-medical users, some insights can be gleaned from clinical studies. In a 1967 clinical trial in which 100 micrograms of LSD was administered to 128 patients with severe medical conditions (primarily cancer), approximately 30% of participants said they would be unwilling to undergo a repeat administration if offered. ³³ Accounts of clinic use from the 1950s and 1960s, as well as older and contemporary clinical trials, have also documented some participants refusing re-treatment with LSD^34–37 and psilocybin.^38–40 In one case series of 36 patients with various conditions, one participant refused further LSD doses after their first treatment. ⁴¹ In a 1964 clinical trial of 100 micrograms of LSD for pain in patients with severe medical illnesses, though LSD proved to have favorable analgesic effects, 16% of participants refused a second dose. ⁴² Of course, many of these data are quite dated and may not be generalizable due to the potential differential impact of set and setting on the LSD’s subjective effects in clinical and non-clinical settings and populations. Some individuals may cease LSD use because they feel they have experienced sufficient psychological or spiritual growth after a single or a few doses, a phenomenon observed in psilocybin clinical research. ⁴⁰

Further research should investigate potential changes in the prevalence of past-year LSD use and its associated factors, including time since initial use, among lifetime LSD users. Additionally, it would be valuable to explore the impact of microdosing on the recency of last LSD use among users. According to the RAND Psychedelic Survey, 47% of past-year psilocybin users reported microdosing during their last use compared to 66% of past-month users. ¹⁴ Among past-year psilocybin users, 4% reported using psilocybin 11 or more days in the past year compared to 10% of users who microdosed during their last experience. Furthermore, it would be worthwhile to investigate the relationship between having access to a guide during LSD use, including past-year LSD use, since 40% of past-year psilocybin users in that survey reported being supervised during their last use.

Limitations

The primary strength of this study is that it provides a unique look at repeat LSD use within a nationally representative sample. However, there are important limitations. For example, past-year LSD use is an imputed variable in the NDSUH dataset, and the NSDUH also relies on participants’ retrospective self-report, which could lead to underreporting of LSD and other substance use. The survey’s retrospective nature can also lead to misremembering when LSD use was initiated. For example, Table 2 shows that one participant aged 18–25 reported initiating LSD use 21–25 years ago, which seems unlikely. Fortunately, this appears to be a very rare event within the dataset. Another limitation is the restriction of NSDUH participation to the civilian, non-institutionalized population. Although this represents 97% of the US population, ²³ it excludes individuals in institutional group quarters such as hospitals, prisons, nursing homes, and addiction treatment centers, who may have different patterns of LSD use and demographics. Causation cannot be determined from these types of data, necessitating other study designs to more specifically explore the misuse potential of LSD. Additional limitations include the lack of data on the total number of LSD uses, doses used (including whether macro or microdoses were used), settings of use, and motivations for use. While the NSDUH does provide data on the total number of days used for any hallucinogen in the past year and past 30 days, it does not provide this information for specific hallucinogens. Additionally, our evaluation of problematic hallucinogen use and its relationship with past-year LSD use was based on the NSDUH variable for hallucinogen dependence, which reflects DSM-IV criteria. This does not capture the broader, more current Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) conceptualization of hallucinogen use disorder, potentially limiting the scope of our findings.

One further limitation is that we used data gathered prior to the COVID-19 pandemic, so both frequency and correlates of past-year LSD use in this cohort may have changed since that time. In support of this possibility, a study of psilocybin users found that many (∼33%) changed their use frequency during the pandemic. ⁴³ Future iterations of nationally representative surveys may further clarify how the COVID-19 pandemic impacted LSD use in the US.

Conclusions

Past-year LSD use is infrequent among LSD users who initiated LSD use at least 5 years ago. Prevalence of past-year LSD use declines with time since LSD use initiation, with a 7% decrease in odds of past-year use with each passing year within this group. Perceived risk and availability of LSD were the factors demonstrating the largest odds ratios for past-year LSD use. Further research is necessary to understand the frequency of LSD use among lifetime LSD users and factors associated with persistence or cessation of LSD use.

Authors’ Contributions

B.S.B.: Conceptualization, methodology, writing—original draft, writing—review and editing, and supervision. A.A.: Conceptualization and writing—review and editing. J.W.: Conceptualization and writing—review and editing. F.K.: Writing—review and editing. E.N.D.: Data curation, methodology, formal analysis, and writing—review and editing.