This survey study (n=201) finds that reductions in death anxiety mediated the effects of the (acute) mystical experience on life satisfaction. Death anxiety did not mediate any of the effects of psychological insight.
Research over the past several decades suggests that meaningful psychedelic experiences can engender long-term effects on subjective wellbeing. However, less research has investigated the psychological mechanisms through which these effects may emerge. In the present study, participants (N = 201) completed an online survey that retrospectively measured the acute effects of a meaningful psychedelic experience, as well as changes in subjective well-being and death anxiety. Reductions in death anxiety significantly mediated the effects of mystical experience on satisfaction with life, positive affect, and negative affect. Reductions in death anxiety did not mediate any of the effects of psychological insight. Although correlational, the findings are consistent with the hypothesis that some of the benefits of psychedelic-induced mystical experiences on subjective well-being may emerge due to reductions in death anxiety. Nevertheless, further research is needed to establish a causal effect of reduced death anxiety on well-being in the context of psychedelic experiences.
Over the past two decades there has been renewed interest in the therapeutic potential of serotonergic psychedelics, yet the psychological mechanisms linking acute subjective effects to longer-term benefits remain poorly understood. Obsessive-Compulsive Disorder (OCD) is a common and debilitating condition (lifetime prevalence around 2%) that is only partially responsive to existing treatments, and preliminary case reports and small trials have suggested that psychedelics may sometimes reduce OCD symptoms. Parallel lines of research indicate that psychedelics can occasion strong subjective states such as mystical experiences and acute psychological insights, and can produce longer-lasting changes in constructs such as meaning in life, connectedness, and attitudes to death. Moreton and colleagues designed the present study to test whether reductions in death anxiety and changes in obsessive beliefs might help explain associations between acute psychedelic effects and self-reported reductions in obsessions and compulsions. The study tested four preregistered hypotheses: that mystical and insight experiences would be associated with reductions in OCD symptoms (H1); that these acute effects would predict reductions in death anxiety and obsessive beliefs (H2); that reductions in those mediators would be correlated with OCD symptom changes (H3); and that death anxiety and obsessive beliefs would mediate the relationship between acute psychedelic effects and reductions in obsessions and compulsions (H4).
Papers cited by this study that are also in Blossom
Aday, J. S., Davis, A. K., Mitzkovitz, C. M. et al. · ACS Pharmacology and Translational Science (2021)
Andersen, K. A. A., Carhart-Harris, R. L., Nutt, D. J. et al. · Acta Psychiatrica Scandinavica (2020)
Barrett, F. S., Johnson, M. W., Griffiths, R. R. · Journal of Psychopharmacology (2015)
Carhart-Harris, R. L., Bolstridge, M., Rucker, J. et al. · Lancet Psychiatry (2016)
This was a retrospective, cross-sectional online survey conducted from January to June 2021. Participants were eligible if they were aged 18 or older, fluent in English, and had taken a single dose of a serotonergic psychedelic (psilocybin, LSD, DMT, ayahuasca, or mescaline) that led to a subjectively significant or emotionally intense experience. Recruitment occurred via social media and online forums. Of 854 people who clicked the study link, 486 consented and completed the survey; after prespecified exclusions (rapid completion, floor scores on OCD measures before the experience, response patterning, or the psychedelic experience occurring <1 week or >5 years prior), the final sample comprised 312 participants. Participants first provided demographics and details of the psychedelic episode (substance, dose level, route, time since experience, concomitant substances). They then completed measures reflecting on that single meaningful experience. Acute subjective effects were assessed with the MEQ30 (Mystical Experience Questionnaire) and the Psychological Insight Questionnaire (PIQ). OCD symptomatology before and after the target experience was captured using the Yale–Brown Obsessive Compulsive Scale (Y-BOCS) and the Vancouver Obsessive Compulsive Inventory (VOCI); obsessive beliefs were measured with the OBQ‑20 and death anxiety with the revised Collett–Lester Fear of Death Scale (CLFD‑R). The ‘‘before’’ measures asked participants to recall the three months prior to the psychedelic experience, while the ‘‘after’’ measures asked participants to report their current state. All scales showed excellent internal consistency in the present sample. Change scores were computed by subtracting ‘‘before’’ from ‘‘after’’ scores. To create a single index of OCD change, z-scores from the Y-BOCS and VOCI change scores were averaged. Statistical analyses used SPSS 26: paired-samples t-tests tested pre–post differences, and mediation analyses employed Hayes’ PROCESS macro (Model 4) with 5,000 bootstrap samples and 95% confidence intervals. Two mediation models were run to examine the unique effects of mystical experience and psychological insight, entering total change on the CLFD‑R and OBQ as parallel mediators.
The final sample had a mean age of 29.38 years (SD = 8.13, range 18–62). All psychometric measures displayed high internal consistency in this sample (for example, MEQ30 α = .98; PIQ α = .97; Y-BOCS pre α = .88, post α = .91; VOCI pre α = .98, post α = .99; OBQ pre α = .98, post α = .99; CLFD‑R pre α = .96, post α = .97). Descriptive statistics for lifetime psychedelic use and experience characteristics were reported in an appendix (not reproduced here). Paired-samples comparisons indicated that pre-scores were significantly higher than post-scores for all facets of death anxiety and for OCD symptom measures, consistent with reported reductions following the indexed psychedelic experience. Pearson correlations showed that change scores for death anxiety and obsessive beliefs were positively associated with change scores on both OCD measures and their subscales. Change scores were calculated as after minus before (the text indicates subtraction of before from after, which the authors used to index reported change). Regarding predictors, both acute mystical experience and psychological insight scores predicted reductions in obsessions and compulsions, and both were associated with reductions in death anxiety and obsessive beliefs. In mediation analyses the pattern differed by predictor: mystical experience had a significant total effect and a significant direct effect on OCD symptom change, and both indirect pathways — via reductions in obsessive beliefs and via reductions in death anxiety — were statistically significant. Psychological insight showed a significant total effect on OCD symptom change, but neither its direct nor its indirect effects (via obsessive beliefs or death anxiety) were significant in the mediation model when entered alongside mystical experience. The extracted text reports significance of these paths but does not give the exact effect sizes, confidence intervals, or p-values for the reported paths in the body of the extraction.
Moreton and colleagues interpret their findings as broadly consistent with the study hypotheses: participants who reported stronger acute psychedelic-occasioned mystical and insight experiences also reported larger reductions in obsessions and compulsions, and these acute effects were associated with reductions in obsessive beliefs and death anxiety. The authors place particular emphasis on mystical experience, which both predicted reduced death anxiety and showed indirect effects on OCD symptom change through reductions in death anxiety and obsessive beliefs. Psychological insight, while correlated with symptom change, did not show significant indirect pathways through the two mediators when modelled simultaneously with mystical experience. The discussion situates these results within existing frameworks. The authors reference models that posit belief change under psychedelics (for example, the REBUS model) and prior evidence linking mystical states to lasting personal transformation. They suggest that psychedelic-occasioned reductions in existential fear (death anxiety) and in maladaptive obsessive beliefs could be two complementary pathways — one existential/affective and one cognitive — by which psychedelic experiences relate to reduced OCD symptomology. At the same time they stress that the mediation is cross-sectional and therefore does not establish temporal causality; reverse causation, unmeasured confounders (for example, neurobiological processes such as 5‑HT2A activation or neuroplasticity), and recall bias could account for some or all observed associations. Several limitations acknowledged by the authors include the retrospective design and potential inaccuracies in recalled pre‑experience symptoms, variable time elapsed since the indexed experience for different participants, possible priming effects of death-related questions, recruitment bias from online forums favouring pro-psychedelic respondents, selection of only subjectively meaningful experiences (thereby underrepresenting neutral or negative experiences), lack of a control group, and insufficient power to examine drug type, dose, or concomitant substances. The authors also note that a minority of participants reported increases in death anxiety or OCD symptoms, implying that psychedelics may worsen outcomes for some people. For future work they recommend prospective designs, qualitative inquiry to clarify mechanisms, investigation of behavioural pathways (for example, reductions in avoidance), and trials that integrate psychotherapy to test ‘‘psychedelic psychotherapy’’ approaches and the moderating roles of set and setting.
The authors conclude that while research on serotonergic psychedelics and OCD is still emergent and causal inferences cannot be drawn from the present design, their findings provide further evidence that personally meaningful psychedelic experiences can be associated with self-reported reductions in obsessive and compulsive symptoms. The magnitude of those reductions was related to the strength of acute subjective effects, particularly mystical experience, and reductions in death anxiety and obsessive beliefs appear to be plausible mechanisms linking acute effects to symptom change. The authors recommend that future studies use designs with greater control over extraneous variables and examine individual and situational moderators of psychedelic effects on OCD symptomology.
The past two decades has seen a resurgence of research into the therapeutic potential of psychedelic drugs. However, despite a growing amount of research into the clinical potential of these substances, little is known about the psychological mechanisms through which their benefits emerge. The main aim of the present study was to investigate self-reported changes in death anxiety and obsessive beliefs as potential psychological mechanisms underpinning the effects of meaningful psychedelic experiences on OCD symptomology.
Obsessive-Compulsive Disorder (OCD) is a serious and often debilitating mental illness, with a lifetime prevalence of around 2%. OCD is characterised by obsessions (i.e., recurring and distressing intrusive thoughts, images, or urges) and/or compulsions (i.e., repetitive behaviours or cognitions aimed at reducing the distress caused by an obsession or preventing a feared event; American Psychiatric Association, 2013). OCD frequently occurs alongside CONTACT Sam G. Moreton smoreton@uow.edu.au Supplemental data for this article can be accessed at. comorbid anxiety and mood disordersand is associated with a range of negative outcomes, including increased suicidality. Despite OCD often causing severe functional impairment, individuals with the disorder experience symptoms for an average of seven years before seeking treatment. Several barriers to treatment and recovery exist, including stigma, misconceptions surrounding OCD, limited access to qualified therapists, and treatment non-adherence. Despite these barriers, evidence-based treatments for OCD do exist. Selective serotonin reuptake inhibitors (SSRIs) are the most well-established pharmacological treatment for OCD, and growing research suggests that clomipramine (a tricyclic antidepressant) is equally as efficacious. Among psychotherapeutic interventions, cognitive behavioural therapy (CBT) is the gold-standard psychological treatment for OCDand has been shown to significantly reduce symptoms in both children and adults. Nevertheless, gold-standard treatments are still limited in effectiveness -around a quarter of people with OCD do not achieve a significant treatment response (defined as a > 25-35% reduction in severity) following treatment with SSRIs or CBT. Furthermore, even among OCD patients that do have a significant reduction in severity of illness, many continue to have some level of residual impairment. Thus, it is crucial to consider ways to improve or complement current treatments.
The term "psychedelics" is typically used to refer to drugs such as psilocybin, mescaline, 5-methoxydimethyltryptamine (5-MEO-DMT), lysergic acid diethylamide (LSD) and N, N-dimethyltryptamine (N, N-DMT;. These drugs are agonists of the serotonin 5-HT2A receptor, and cause marked shifts in mood, cognition, behaviour, and perception. Although the use of psychedelics comes with risks, the past two decades has seen a resurgence of research into potential benefits of their use in both naturalisticand clinical settings (e.g.,. More specifically, recent work has examined the effects of psychedelic-assisted psychotherapy, demonstrating reductions in anxiety, depression, end-of-life anxiety and symptomology of substance use disorders (see dos. Although these findings are largely preliminary and more research is needed to understand the role of personal and situational factors (commonly referred to as "set" and "setting";, the emerging research suggests that psychedelic use can, in some circumstances, have salutary effects.
In addition to psychedelic research focussed more broadly on anxiety, there has also been preliminary research looking specifically into the effects of psychedelic use on OCD symptomology. For instance, several case studies have documented reductions in OCD symptoms that were attributed by the users to the use of psychedelics. Early work byreported a single case study where obsessions disappeared after consuming psilocybincontaining mushrooms. Similarly,described the case of a patient who experienced a total elimination of symptoms after one year of consuming psilocybin. More recently, Lugo-Radillo and Cortes-Lopez (2021) reported the case of a patient with debilitating, long-term symptoms who only partially responded to intensive pharmacological treatment. After consuming psilocybin-containing mushrooms and noticing a reduction in his symptoms for two weeks post-ingestion, the patient continued to consume approximately two grams of dried mushrooms every two weeks. The patient reported a reduction in their OCD symptoms after each consumption, which continued up to six months after the initial use. Further, whilst his score on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) indicated "extremely severe" OCD three days before initial consumption, this improved to 'mild' OCD symptoms after six months. In a small-scale trial,evaluated the safety, tolerability, and therapeutic effects of psilocybin administration in nine patients with OCD who had not responded to at least one treatment trial with serotonin-reuptake inhibitors. All participants showed marked reductions in OCD symptomology during one or more of the sessions, varying from a 23%-100% decrease in Y-BOCS scores. In sum, there is some emerging evidence suggesting that serotonergic psychedelics may often reduce symptoms of OCD. Nevertheless, the quality of evidence is still very limited and further research is needed to understand not only whether serotonergic psychedelics typically reduce OCD symptomology but also why they may do so.
Although relatively little is yet known about the underlying mechanisms through which the therapeutic effects of psychedelics may emerge, a growing body of work suggests that aspects of the subjective experience may be crucial to understanding their therapeutic benefits (see. The literature has seen a specific focus on the role of the psychedelicoccasioned mystical experience: a psychological state comprised of a sense of oneness, transcendence of space and time, ineffability and strong positive emotions, such as awe. An expansive collection of studies has now linked the strength of psychedelic-occasioned mystical experiences with the therapeutic benefits of psychedelic use (see. For instance, clinical trials have found total scores on the Mystical Experience Questionnaire (MEQ) to have moderate to strong negative correlations with changes in smoking, depression, and anxiety in the context of severe illness. Although the bulk of the focus in the literature looking at acute psychedelic experiences has focussed on mystical experiences, other aspects of the experience might also contribute to their therapeutic effects. One such component is what have been referred to as acute insight experiences. Although extant research into the topic of insight in the context of psychedelic experiences is limited,recently developed the Psychological Insights Questionnaire (PIQ), which comprises two facets: (a) avoidance and maladaptive patterns insights and (b) goals and adaptive patterns insights. The aim of the measure is to capture "realizations or discoveries about personality, relationships, behavioural patterns or emotion") and reflects earlier contentions that overcoming psychological resistance and bringing to the fore typically unconscious aspects of cognition and behaviour may be key beneficial aspects of the psychedelic experience.found that PIQ scores were only moderately correlated with MEQ scores suggesting that they both capture distinct qualities of the acute psychedelic experience. Mirroring research suggesting that insight may be an important component of many psychotherapies, in retrospective, uncontrolled surveys,andfound that scores on the PIQ predicted subsequent positive changes in well-being, anxiety and depression following a psychedelic experience. Although these findings are indicative that ostensible insights during psychedelic experiences may be important for their therapeutic benefits, further research into the role of insight experiences is sorely needed in this space.
In addition to acute effects such as mystical and insight experiences, researchers have also considered longerterm changes in trait-like constructs that may mediate the longer-term effects of the acute effects, such as increased psychological flexibility, meaning-in-life, and increased connectedness to the self and other people. Another potential therapeutic mechanism of psychedelics is through reducing death anxiety. Although little research has investigated why psychedelics may reduce fears of death,propose that potential explanations include exposure to a death-like experience (seeand altered metaphysical and/or religious beliefs. As with other enduring effects of psychedelics, there is some evidence that the subjective quality of the psychedelic experience may play a role here, with several studies finding changed attitudes towards death following psychedelic use to correlate with the strength of the mystical experience.
Given that death anxiety has been suggested to be a transdiagnostic construct underlying many manifestations of psychopathology, findings suggesting that psychedelics may reduce death anxiety have significant clinical implications. In particular, death anxiety has been argued to play a central role in OCD, with many related behaviours being directly linked to fears of death. For example, individuals with the contamination subtype of OCD often explicitly associate their behavioural compulsions with a fear of fatal diseases, poisons, toxins, and bodily fluids that may cause contamination and subsequent death. Further, those who engage in compulsive checking may repeatedly inspect electrical outlets, stoves, heaters, and locks to prevent a potentially fatal fire, electrocution, or home invasion. Sufferers might also fear that their intrusive thoughts can magically cause the death of loved ones and engage in repetitive blinking, tapping, or counting rituals, to prevent death. Growing empirical evidence supports these clinical observations. First, death anxiety has been found to predict the disorder pathway to OCD, with higher levels of death fears predicting a greater number of mental illnesses prior to the onset of OCD. Further, death anxiety has been shown to be significantly correlated with six different symptom domains of OCD, including contamination concerns, checking, obsessions, hoarding, indecisiveness, and "just right" (e.g., an urge to reorder one's environment or possessions until it feels 'right';. In addition, while other existential concerns (e.g., identity concerns, guilt) have been proposed to be theoretically relevant to OCD, evidence supports the uniquely predictive role of death anxiety in certain presentations. In one study examining the obsessions subtype specifically, death anxiety was the only existential concern to be significantly associated with aggressive obsessions. Experimental studies have also demonstrated the causal role of death anxiety in at least one subtype of OCD;demonstrated that reminders of death significantly increased compulsive washing behaviour among individuals diagnosed with the contamination subtype of OCD, compared to those who had not been reminded of death.
In addition to death anxiety, psychedelics may foster improvements in OCD symptomology through their ability to facilitate enduring changes in beliefs pertaining to the nature of the world and the self. Carhart-Harris and Friston (2019) introduced the REBUS (relaxed beliefs under psychedelics) model of psychedelic effects, suggesting that psychedelics increase the sensitivity of high-level beliefs to bottom-up information (either arising externally or internally), which may facilitate belief change. In the context of OCD, psychedelics may enable the relaxation of irrational beliefs that, although potentially serving functional purposes (e.g., ego protection), nonetheless, lead to psychopathology. While this relaxation of beliefs may be temporary, it may open up a critical window that leads to enduring changes in specific maladaptive beliefs that maintain obsessions and compulsions. Whilst various conceptual models of OCD exist, all leading models highlight the role of dysfunctional beliefs in the development and maintenance of the disorder (e.g.,. Such models propose that these underlying beliefs predispose individuals to obsessions and compulsions by driving behavioural attempts to reduce distress caused by unwanted thoughts. Several domains of maladaptive beliefs have been consistently found to be associated with OCD. These include an inflated sense of personal responsibility (i.e., believing it would be one's own fault should a feared event occur), need for uncertainty (i.e., believing that one cannot cope or function without complete certainty), estimation of threat (i.e., viewing negative outcomes as being more likely and more catastrophic than others), and importance of thoughts (i.e., overestimating how meaningful or significant thoughts are, resulting in excessive attempts to suppress or prevent thoughts; Obsessive Compulsive Cognitions Working. A body of research has demonstrated the relationship between these obsessive beliefs and OCD symptoms, both in clinical samples of individuals diagnosed with OCD (e.g.,, and in non-clinical samples (e.g.,. Obsessive beliefs have also been found to be more predictive of OCD symptoms than other theoretically-relevant constructs such as experiential avoidance (i.e., a tendency to avoid unwanted internal experiences, such as anxiety) and cognitive fusion (i.e., a tendency to over-attach to internal experiences;. In line with this, obsessive beliefs have been seen as a central mechanism by which psychological treatments may improve OCD symptoms (e.g.,. For example, CBT interventions arguably challenge obsessive beliefs both directly and indirectly, such as by explicitly disputing the client's overestimates of threat (e.g., examining the objective likelihood of contracting a particular illness), or by doing so behaviourally, such as through exposure and response prevention (e.g., by demonstrating that touching a feared contaminant is insufficient to cause illness). Empirical research supports this theorised mechanism. In a study of inpatients diagnosed with OCD,found that changes in obsessive beliefs early in treatment significantly predicted OCD symptoms at discharge, suggesting that shifts in beliefs precede changes in affect and behaviour. This finding is consistent with numerous studies demonstrating that reductions in obsessive beliefs predict treatment outcome for OCD (e.g.,, and that changes in particular obsessive beliefs (e.g., perfectionism and need for certainty) mediate treatment response. Thus, in addition to death anxiety, it is possible that reductions in obsessive beliefs is another mechanism by which psychedelic experiences may produce changes in OCD symptoms.
The main aim of the present study was to investigate whether changes in death anxiety and obsessive beliefs mediate the effect of significant psychedelic experiences on changes in obsessions and compulsions. We hypothesised that: (H1) Acute psychedelic effects (mystical experiences and psychological insight effects) would be significantly associated with changes in obsessions/compulsions following a psychedelic experience; (H2) Acute psychedelic effects would be associated with reductions in death anxiety and obsessive beliefs; (H3) Reductions in death anxiety and obsessive beliefs would be positively correlated with reductions in obsessions/compulsions; and (H4) Death anxiety and obsessive beliefs would mediate the relationships between psychedelic effects and reductions in obsessions/compulsions.
The study was approved by the UOW & ISLHD Social Sciences Human Research Ethics Committee (Approval number: 2020/289). Participants were eligible to take part in the study if they identified as being (1) 18 years or older, (2) able to read, write and speak English fluently, and (3) had taken a single dose of a serotonergic psychedelic (i.e., psilocybin, LSD, DMT, Ayahuasca, or mescaline) that led to a subjectively significant or emotionally intense experience. Participants were recruited online from January to June 2021 via social media and online forums as part of a crosssectional survey. Of all individuals who clicked the advertisement link (n = 854), 486 consented and completed the survey. Out of these, 174 participants were removed from the data analysis due to (a) completing the survey in less than 10 minutes (n = 41), (b) reporting no or very little obsessions or compulsions in the time-period before using the psychedelic (as indicated by floor scores on both of the OCD measures; n = 5), (c) selecting the same response options for all questions in more than two measures (n = 40), or (d) indicating they had taken the psychedelic less than a week ago (n = 53), or more than 5 years ago (n = 35). This resulted in a final sample size of 312 participants.
After clicking on the survey link, participants were directed to the survey and provided information outlining the broad topic of the study (i.e., investigating psychedelic experiences and how they affect obsessive thoughts and compulsions), participation eligibility criteria, and consent. To reduce the likelihood of response biases, this information did not outline the specific hypotheses of the study. Participants were also informed that by completing the study, they would be given the option to enter a draw to win one of two $100 AUD gift vouchers. After completing questions relating to demographics and history of psychedelic use, participants first answered questions about their chosen psychedelic experience itself. After this, they answered measures that involved rating their obsessions and compulsions, obsessive beliefs, and death anxiety. These measures were first worded so that participants answered retrospectively from the perspective of the preceding three months before the experience ("before" measures). Next, participants then answered these same measures, but now pertaining to how they perceive themselves at present ("after" measures). Therefore, to assess reported change over time, the measures of obsessions and compulsions and death anxiety were administered twice, retrospectively, Finally, at the end of the survey, participants were presented with a debriefing statement that described the specific aims of the study.
First, demographic information was collected including the age, gender, race/ethnicity, country/ region of residence, primary spoken language, religion, and political orientation of each respondent (see Appendix A).
Participants were asked to reflect on one meaningful psychedelic experience to answer the following questions about their experience. Participants were asked to report which psychedelic substance they had used (i.e., psilocybin, LSD, DMT, Ayahuasca, or mescaline), the subjective level of dose (i.e., Low, Moderate, Moderately High, High), route of administration (i.e., Oral, Sublingual, Smoked, Vaporized, or "Other"), and length of time since the experience. Respondents were also asked to report any additional substances they took at the same time as their chosen psychedelic experience. These details of the psychedelic experience are outlined in Appendix A. Participants then completed the following three measures listed below, again reflecting on the same meaningful psychedelic experience.
The Revised Mystical Experiences Questionnaire (MEQ30;was used to assess subjective mystical experiences elicited by taking a psychedelic substance. Participants reflected on their chosen experience with a psychedelic and rated the extent to which each of 30 items applied during the session on a 6-point Likert-type scale (0 = "None; Not at all" to 5 = "Extreme; More than ever before in my life"). The questions within the MEQ30 measure core characteristics of mystical experiences previously identified in the literature including Positive Mood (e.g., "Experience of ecstasy."), Transcendence of Space and Time (e.g., 'Sense of being "outside" of time, beyond past and future.'), Ineffability (e.g., "Feeling that you could not do justice to your experience by describing it in words.") and a Sense of Internal and External Unity ("Experience of oneness or unity with objects and/or persons perceived in your surroundings."). Following previous recommendations, a MEQ30 total score was used as a measure of participants' mystical experience during the psychedelic experience.found high internal consistency (α = .93) for the MEQ30, supporting its reliability as a measure of mystical experiences. The present study also found excellent internal consistency (α = .98).
The Psychological Insight Questionnaire (PIQ;was used to assess the extent to which respondents experienced acute insight after taking the psychedelic. Acute insight, in this case, includes enhanced awareness of emotions, beliefs, memories, relationships, or behaviours. Participants were asked to reflect on their chosen experience with a psychedelic and to rate the intensity of 28 insight experiences 1 (e.g., "Realized ways my beliefs may be dysfunctional") during the reported experience. Items were scored on a 6-point Likert scale (0 = "None; Not at all" to 5 = "Extreme; More than ever before in my life"). A total score was calculated using the mean of each item response.found that this scale had excellent internal reliability (α = .93), which was also reflected in the present study (α = .97).
The Yale Brown Obsessive-Compulsive Scale (Y-BOCS;was used to assess for changes in obsessions and compulsions. The Y-BOCS is a commonly used measure of OCD symptom severity and treatment response and has previously been found to have good internal consistency. This measure contains ten items measuring time, interference, distress, resistance and control of obsessions and compulsions. The items are rated from 0 ("No symptoms") to 4 ("Severe symptoms") and yield a global severity score. The present study had excellent internal consistency (pre; α = .88 ; post; α = .91). The Vancouver Obsessive Compulsive Inventory (VOCI;was also used to assess changes in the different subtypes of OCD. It is a widely used self-report instrument with 55 items that measures obsessive-compulsive symptoms using six subscales: Contamination (12 items), Checking (6 items), Obsessions (12 items), Hoarding (7 items), Just Right (12 items), and Indecisiveness (6 items). Each item is rated on a 5-point response scale from "Not at all" (1) to "Very much" (5). The VOCI has been previously found to have high internal consistency and strong correlations with other measures of OCD symptomology. The present study had excellent internal consistency (pre; α = .98 ; post; α = .99).
The Obsessive Beliefs Questionnaire (OBQ-20;was used to measure changes in the beliefs considered important in the development and maintenance of OCD. Each of the 20 items is rated using a seven-point Likerttype scale, ranging from 1 ("Disagree Very Much") to 7 ("Agree Very Much"). It contains four subscales: Threat (e.g., "I am more likely than other people to accidentally cause harm to myself or to others"), Responsibility (e.g., "Even if harm is very unlikely, I should try to prevent it any cost"), Importance and Control of Thoughts (e.g., "Having bad thoughts means I am weird or abnormal"), and Perfectionism/Intolerance of Certainty (e.g., "I must keep working until it's done exactly right"). Higher scores indicate higher levels of each subscale. Previous research found excellent internal consistency and moderate correlations with OCD symptomology. The present study had excellent internal consistency (pre; α = .98 ; post; α = .99).
The revised Collett-Lester Fear of Death Scale (CLFD-R;was used to determine whether death anxiety is a potential mediator of acute psychedelic experiences on changes in obsessions and compulsions. This is a 28-item measure with four subscales (7 items each): Death of Self (e.g., "the total isolation of death"), Death of Others (e.g., "The loss of someone close to you"), Dying of Self (e.g., "The pain involved in dying"), and Dying of Others (e.g., "Having to be with someone who is dying"). Items were rated on a 6-point Likert-type scale from 1 ("Not at all") to 5 ("Extremely"). The CLFD-R previously been found to have excellent internal consistency. The present study had excellent internal consistency (pre; α = .96 ; post; α = .97).
The data were analysed with SPSS 26. Paired samples t-tests were performed to determine whether there were significant differences in the mean scores on the measures for before and after the meaningful psychedelic experience. Mediation analyses using Hayes' PROCESS macro (5000 bootstrap samples, 95% confidence intervals; Model 4;were conducted to test for indirect effects of mystical experience and psychological insight on changes in OCD symptomology through changes in OCD beliefs and death anxiety. To follow the precedent set byof testing the unique effects of mystical experience and psychological insight, two mediation analyses were conducted with each of these variables respectively either as the independent variable or as a covariate. The Total change score for the CLFD-R scale and the Total change score for the OBQ were entered as parallel mediators to investigate unique pathways through these variables. To compute a total change score for OCD symptomology, we combined the change scores of the two OCD measures, (Y-BOCS; VOCI), by calculating z-scores for each participant on these variables and then computing a new variable with the average of these two z-scores.
Participants were on average 29.38 years old (SD = 8.13 years; range = 18-62 years). Other demographic characteristics, as well as information regarding lifetime use of psychedelics and characteristics of the meaningful psychedelic experience, are presented in the Appendix. Descriptive statistics for each of the main study variables (i.e., mystical experiences, psychological insight, death anxiety, obsessive beliefs, and OCD symptoms) are presented in Table.
As seen in Table, pre-scores were significantly higher than post-scores for all facets of death anxiety and OCD symptomology. Pearson bivariate correlation coefficients were used to assess relationships between the main study variables.
Consistent with Hypothesis 1, acute psychedelic effects (i.e., mystical experiences, and psychological insight) during a psychedelic experience predicted changes in obsessions and compulsions. In support of Hypothesis 2, acute psychedelic effects significantly predicted reductions in death anxiety and obsessive beliefs. Supporting Hypothesis 3, death anxiety and obsessive belief change scores were significantly positively correlated with change Change scores were calculated by subtracting participants' scores on the "before" measures from those on the "after" measures. scores for both OCD measures and their subscales (see Tableand Figures).
For mystical experience, both the total and direct effect on OCD symptomology were significant. Both indirect effects (i.e., through OCD beliefs and death anxiety) were also significant. The total effect of psychological insight was significant. However, no direct or indirect effects of psychological insight on OCD symptoms were significant (see Table). Individual paths are reported in Figure.
The present retrospective cross-sectional study aimed to investigate whether: (H1) psychedelic-occasioned mystical and/or insight experiences were associated with reductions in obsessions and compulsions, (H2) these acute psychedelic effects also were correlated with reductions in death anxiety and obsessive beliefs, (H3) reductions in death anxiety and obsessive beliefs were associated with reductions in obsessions/compulsions, and (H4) reductions in death anxiety and obsessive beliefs would mediate the relationships between acute psychedelic effects and reductions in OCD symptomology. Overall, the findings of the present study are consistent with these hypotheses. Consistent with a preliminary trial into the effects of psilocybin on OCD symptomologyas well as several case studies (e.g.,, there were significant self-reported reductions in obsessions and compulsions after the participants' chosen psychedelic experience. We built on previous findings by showing that the acute psychedelic effects themselves (i.e., mystical experiences; psychological insight) were associated with reductions in OCD symptomology. Although emerging evidence has suggested that acute subjective effects may be crucial to understanding the benefits and harms of psychedelic use, the relationship between subjective effects and OCD specifically was yet to be explored in the literature prior to this study. The significant relationship between mystical experience and symptom change is consistent with previous research suggesting that psychedelicoccasioned mystical experiences often result in personal transformations that influence behaviours, cognitions, and emotions, which in turn enable the therapeutic effects of psychedelics. Similarly, the significant association found between insight experiences and changes in OCD symptomology dovetails with recent evidence presented bywho found that psychological insight was a significant predictor of changes in anxiety and depression following a psychedelic experience. Although correlational, the results of the present study are consistent with there being unique effects of both mystical and insight experiences in contributing to reduced OCD symptomology. In line with previous research (e.g.,, the strength of the mystical experience predicted reduced death anxiety. However, when included in a model simultaneously with mystical experience, psychological insight was not a significant predictor of changes in death anxiety in the present study. This was somewhat surprising, as ostensive insights into the nature of consciousness or the meaning of life have been suggested to play a role in why psychedelics might reduce death anxiety and psychological distress. However, the items in the Psychological Insights Questionnaire do not explicitly touch on insights related to metaphysical ideas -the measure has a more specific focus on insights related to adaptive and maladaptive cognitions and behaviours. Thus, the lack of relationship between insights and death anxiety may be due to the narrow breadth of the content domain of the PIQ, rather than being indicative of a lack of relationship between reduced death anxiety and a broader conception of psychological insight. It should also be noted that the PIQ was highly correlated with the MEQ30, which may have blunted the former's predictive power when both were entered simultaneously in the mediation model. Nevertheless, it is interesting that, in the present study, the PIQ was not as strong a predictor of death anxiety as the MEQ30. As noted by, little is yet known about the mechanisms through which psychedelics may reduce death anxiety. The present findings suggest that aspects of the mystical experience may be more important for reducing death anxiety than the insights that psychedelic users may have into their adaptive and maladaptive patterns of cognition and behaviour. Nevertheless, more research is needed to clarify which outcomesdeath anxiety or otherwise -are best predicted by different aspects of the psychedelic experience. Consistent with previous research outside of the context of psychedelics (e.g.,, reductions in OCD symptomology were associated with changes in obsessive beliefs. Further, in line with studies showing the central role of death anxiety in OCD, the present study similarly found that reductions in OCD symptoms were associated with changes in death anxiety. Interestingly, there were indirect effects of mystical experience on OCD symptoms through both death anxiety and obsessive beliefs. Although this mediation was cross-sectional, it is consistent with the notion that psychedelic-occasioned mystical experiences can reduce OCD symptomology and that this may occur via both cognitive (e.g., obsessive beliefs) and existential/affective (e.g., death anxiety) mechanisms.
This study has several limitations that must be considered. First, when conducting cross-sectional mediation analyses, the mediator and dependent variable are determined by theory, and it is also possible that the dependent variable causes the mediator. In the case of the present study, it is possible that a reduction in obsessions and compulsions might have led to reduced death anxiety or obsessive beliefs. It also cannot be ruled out that another unmeasured variable may have accounted for these relationships. For example, as noted by, it is possible that observed relations between subjective effects and therapeutic outcomes may be driven by more fundamental neurological processes (e.g., 5-HT2A activation; neuro-plasticity). If that is the case, subjective effects may be statistically associated with therapeutic effects merely due to covarying with these neurological processes. Although recall of OCD symptoms has been shown to be fairy accurateand there are advantages of retrospective pre-post designs, it is possible that participants did not report entirely accurate recollections of their symptoms prior to the psychedelic experience. Unlike several similar recent retrospective studies (e.g.,that asked participants to report on thirty days before and thirty days after an experience, the reporting of outcomes from the perspective of "now" in the present study meant that a significant time-period had passed for some participants since their psychedelic experience. This may have affected recall due to the passage of time, and/or may have introduced noise due to other life events that may have occurred in the intervening timeperiod. An additional factor to consider is that answering questions relating to death may have primed participants to answer subsequent questions differently. As there is some research to suggest that priming people with thoughts of death can increase OCD symptomology, it may possibly also affect the recall and/or reporting of symptomology. The sourcing of participants from online forums likely increased the recruitment of participants with positive attitudes towards psychedelics, which may also have further compromised recollections. Furthermore, it should also be noted that the present study specifically sampled participants who had had a subjectively meaningful or significant experience with psychedelics. Thus, participants who might have had either an insignificant or a negative experience would have been underrepresented. Furthermore, the study was not restricted to participants with a diagnosis of OCD. As this sample was likely to be unrepresentative in a number of ways, care should be taken in extrapolating from the present findings to general claims about the efficacy of psychedelics in the treatment of OCD. An additional limitation of the design is the absence of a control group, which leaves open the possibility that changes over time may have occurred for reasons other than the psychedelic experience. Lastly, the present study was not sufficiently powered to test for differences in results as a function of the type or dosage of the drug taken, nor whether the use of other drugs may have affected the results, and a range of pharmacological, psychological and sociodemographic factors may modulate the effects of these drugs. Although there was a general trend towards reductions of OCD symptomology, obsessive beliefs and death anxiety following the psychedelic experience, not all participants reported reductions. Indeed, a minority of participants reported increases on these variables over time. This is especially striking given the aforementioned plausibility of a trend towards positive bias in responses. Although it is plausible that some of these changes (both positive and negative) could be due to other life events that occurred in the intervening time, it remains a possibility that psychedelic use could worsen some people's death anxiety and/or OCD symptomology. To our knowledge, no published research has yet investigated potential variables (e.g., aspects of set and setting) that might drive the effects of psychedelics on death anxiety and OCD symptomology in either positive or negative directions.
Given these limitations, further research is sorely needed to understand how and why psychedelics might affect OCD symptomology. In addition to ongoing clinical trials, future research could consider prospective studies tracking participants' psychedelic use, death anxiety, and obsessive beliefs and OCD symptomology, in order to better account for issues inherent to retrospective designs. The present study had a focus on cognition (e.g., obsessive beliefs) and existential/emotional concerns (e.g., death anxiety). However, it is possible that behavioural principles may also be at play in why psychedelics may reduce OCD symptomology. In the present study, psychological insights during the psychedelic experience predicted changes in OCD-symptomology, yet there were no significant pathways from insights through changes in obsessive beliefs nor death anxiety. As one aspect of the PIQ involves insights into maladaptive behaviours, it is possible that some participants may have had insights into their own patterns of avoidance (both cognitive (e.g., suppressing anxiety provoking thoughts) and behavioural (e.g., avoiding triggers of compulsions) and this may have reduced obsessions and compulsions largely through longer term, downstream effects of insights in reducing avoidance. Further research may benefit from addressing this possible explanation. In addition, qualitative accounts from users who have reported improvements in OCD symptomology following psychedelics may help clarify the causal mechanisms at play. Further research is also needed to unpack potential synergies between psychotherapy and psychedelic use, or "psychedelic psychotherapy". To date, no published research has looked at the effects of psychedelic psychotherapy for OCD. Although psychedelics may have intrinsic pharmacological effects that may be therapeutic, the current literature also supports that positive outcomes may be amplified when integrated into a larger psychotherapeutic intervention plan. However, it still remains unclear in many instances whether it is the drug itself or the psychedelic-assisted psychotherapy that promotes change. Future research should consider aspects of set and setting (e.g., therapeutic setting) that may moderate the effects of psychedelics on OCD symptomology.
Research into the effects of serotonergic psychedelics on OCD symptomology is still in its infancy. While the design of the present study precludes inferences regarding whether psychedelic use in general typically leads to reductions OCD symptomology, the present study provides further evidence that psychedelic experiences can be associated with reported reductions in OCD symptomology, and that the magnitude of these reductions may be related to the strength of acute subjective effects. The results also support potential roles of death anxiety and obsessive beliefs as relevant mechanisms underpinning the effects of psychedelics on OCD symptomology. The present findings are in line with the suggestion ofthat the capacity of psychedelics to reduce death anxiety may be a significant mechanism involved in their therapeutic effects, even in individuals without life-threatening illness. Future studies should consider testing these mechanisms using designs that allow greater control over extraneous variables, as well as investigating the personal and situational factors that may moderate the effects of psychedelic experiences on OCD symptomology.
1. After the data collection and analysis of this study were complete, the PIQ was recently revised to remove five items that were loading on both subscales. In the present study, we did not look at each subscale separately and all items had acceptable itemtotal score correlations (>.5). Therefore, we have reported the analyses including these five items.
No potential conflict of interest was reported by the author(s).
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