The Challenging Experience Questionnaire: Characterization of challenging experiences with psilocybin mushrooms

“Values of SRMR and RMSEA<0.1, and CFI>0.90 (Browne and Cudeck, 1993; Hu”

“Factorial invariance was assessed in a series of multiplegroup confirmatory factor models using the cfa function in the lavaan toolbox in R (Rossell, 2012), with maximum likelihood estimation.”

“Values of SRMR and RMSEA<0.1, and CFI>0.90 (Browne and Cudeck, 1993; Hu”

“change between modeling steps) indicates noninvariance (Chen, 2007).”

“…research on psychedelics has revived their investigation as therapeutic agents (Bogenschutz et al., 2015; Carhart-Harris et al., 2012, 2016a; Griffiths et al., 2016; Grob et al., 2011; Johnson et al., 2014; Ross et al., 2016) and tools to understand psychosis (Schmid et al., 2015;…”

“, 2011) and anxiety secondary to a life-threatening cancer diagnosis (Griffiths et al., 2016; Ross et al., 2016), and recent large-sample surveys have demonstrated a lower risk for psychological distress and suicidality in those who have endorsed having consumed a classic hallucinogen in the past (Hendricks et al.”

“…States (APZ) questionnaire) have been widely used in behavioral and neuroimaging research of pharmacologically (Gouzoulis-Mayfrank et al., 2005; Griffiths et al., 2006, 2011; Vollenweider et al., 1998) as well as non-pharmacologically induced altered states of consciousness (Hübner, 2007;…”

“…al, 2015; Griffiths et al., 2006, 2011) or spiritual (Kometer et al., 2015) experiences, changes in self-referential processing or “ego dissolution” (Carhart-Harris et al., 2014; Tagliazucchi et al., 2016), altered social processing (Preller et al., 2016), visual imagery (Kaelen et al., 2016),…”

“Recent empirical work has shown the potential value of psilocybin as a treatment for depression (Carhart-Harris et al., 2016a; Grob et al., 2011) and anxiety secondary to a life-threatening cancer diagnosis (Griffiths et al.”

“Guidelines have been described to minimize adverse reactions in controlled settings (Johnson et al., 2008), and incidence of lasting symptoms (including psychosis) related to administration of classic hallucinogens in controlled settings is quite low (Griffiths et al., 2006, 2011; Strassman, 1984;…”

“The recent resurgence of empirical research on psychedelics has revived their investigation as therapeutic agents (Bogenschutz et al., 2015; Carhart-Harris et al., 2012, 2016a; Griffiths et al., 2016; Grob et al., 2011; Johnson et al., 2014; Ross et al., 2016) and tools to understand psychosis…”

“…used in behavioral and neuroimaging research of pharmacologically (Gouzoulis-Mayfrank et al., 2005; Griffiths et al., 2006, 2011; Vollenweider et al., 1998) as well as non-pharmacologically induced altered states of consciousness (Hübner, 2007; Kjellgren et al., 2004; Walach and Kaseberg, 1998).”

“…States (APZ) questionnaire) have been widely used in behavioral and neuroimaging research of pharmacologically (Gouzoulis-Mayfrank et al., 2005; Griffiths et al., 2006, 2011; Vollenweider et al., 1998) as well as non-pharmacologically induced altered states of consciousness (Hübner, 2007;…”

“Approximately 30% of participants in each of three highly controlled experimental studies (total sample: 69 participants and 204 sessions – Griffiths et al., 2006, 2011; Johnson et al., 2014) involving a high dose of psilocybin (0.”

“…change (Carhart-Harris et al., 2016b; Lebedev et al., 2016; MacLean et al., 2011), positive mental health outcomes (Hendricks et al., 2015; Johansen and Krebs, 2015), and enduring positive changes in attitudes, mood and behavior (Griffiths et al., 2008, 2011) occasioned by these compounds.”

“, 2015), personality change (Carhart-Harris et al., 2016b; Lebedev et al., 2016; MacLean et al., 2011), positive mental health outcomes (Hendricks et al.”

“…(Strassman, 1995; Strassman et al., 1994) and the various forms of Dittrich’s Altered States of Consciousness questionnaires (Dittrich, 1975, 1998; Studerus et al., 2010), including the Altered States of Consciousness Rating Scale (OAV) and the Five-Dimensional Altered States of Consciousness…”

“, 2016) and mystical experience (Barrett et al., 2015) are positively associated with well-being, it is not completely clear that the items of the ‘death’ subscale of the CEQ (“Profound experience of your own death” and “Feel as if dead or dying”) are collinear with either mystical experience or ego dissolution.”

“…Rating Scale (HRS) (Strassman, 1995; Strassman et al., 1994) and the various forms of Dittrich’s Altered States of Consciousness questionnaires (Dittrich, 1975, 1998; Studerus et al., 2010), including the Altered States of Consciousness Rating Scale (OAV) and the Five-Dimensional Altered…”

“4%) of those participants reported prolonged symptoms (Studerus et al., 2011).”

“…2006, 2011) or spiritual (Kometer et al., 2015) experiences, changes in self-referential processing or “ego dissolution” (Carhart-Harris et al., 2014; Tagliazucchi et al., 2016), altered social processing (Preller et al., 2016), visual imagery (Kaelen et al., 2016), changes in emotional experience…”

“A more detailed description of the complete methods, measures, and initial findings of the online survey can be found in the original report (Carbonaro et al., 2016).”

“Participants have also attributed positive change in well-being to their psilocybin experience, and this change in well-being has been shown to correlate positively with mystical experience (Garcia-Romeu et al., 2015) and egodissolution (Nour et al.”

“While the experience of ego dissolution (Nour et al., 2016) and mystical experience (Barrett et al.”

“…used questionnaire instruments assessing the subjective effects of classic hallucinogens are the Hallucinogen Rating Scale (HRS) (Strassman, 1995; Strassman et al., 1994) and the various forms of Dittrich’s Altered States of Consciousness questionnaires (Dittrich, 1975, 1998; Studerus et al.,…”

“, 2016) and tools to understand psychosis (Schmid et al., 2015; Vollenweider et al., 1998, 2007).”

“…of the importance of set (participant psychological state) and setting (interpersonal and physical environment), acute adverse effects of psychedelics may generally be minimized and successfully managed in research contexts (Johnson et al., 2008; Metzner et al., 1965; Studerus et al., 2012).”

“, 2016), and recent large-sample surveys have demonstrated a lower risk for psychological distress and suicidality in those who have endorsed having consumed a classic hallucinogen in the past (Hendricks et al., 2015; Johansen and Krebs, 2015).”

“, 2016), changes in emotional experience (Kaelen et al., 2015; Kraehenmann et al., 2015), personality change (Carhart-Harris et al.”

“…acid diethylamide (LSD), mescaline, and dimethyltryptamine (DMT; contained in the sacramental beverage ayahuasca) share a primary pharmacological site of action at the serotonin 2a (5HT2a) receptor, and display striking similarities in their subjective effects (Halberstadt, 2015; Nichols, 2016).”

“…et al., 2016), changes in emotional experience (Kaelen et al., 2015; Kraehenmann et al., 2015), personality change (Carhart-Harris et al., 2016b; Lebedev et al., 2016; MacLean et al., 2011), positive mental health outcomes (Hendricks et al., 2015; Johansen and Krebs, 2015), and enduring…”

“…of Consciousness Inventory (Pekala, 1986), the Minnesota Multiphasic Personality Inventory (Belleville, 1956), the States of Consciousness Questionnaire (Griffiths et al., 2006, 2011), and the Addiction Research Center Inventory (Griffiths et al., 2006, 2011; Haertzen, 1966; Riba et al., 2001).”

“Clinical literature and anecdotal reports indicate that paranoia is a subjective experience frequently represented in challenging experiences with classic hallucinogens (Cohen, 1960; Griffiths et al., 2006, 2011; Strassman, 1984).”

“, 2008), and incidence of lasting symptoms (including psychosis) related to administration of classic hallucinogens in controlled settings is quite low (Griffiths et al., 2006, 2011; Strassman, 1984; Studerus et al., 2011).”

“…change (Carhart-Harris et al., 2016b; Lebedev et al., 2016; MacLean et al., 2011), positive mental health outcomes (Hendricks et al., 2015; Johansen and Krebs, 2015), and enduring positive changes in attitudes, mood and behavior (Griffiths et al., 2008, 2011) occasioned by these…”

“…of Consciousness Inventory (Pekala, 1986), the Minnesota Multiphasic Personality Inventory (Belleville, 1956), the States of Consciousness Questionnaire (Griffiths et al., 2006, 2011), and the Addiction Research Center Inventory (Griffiths et al., 2006, 2011; Haertzen, 1966; Riba et al., 2001).”

“The recent resurgence of empirical research on psychedelics has revived their investigation as therapeutic agents (Bogenschutz et al., 2015; Carhart-Harris et al., 2012, 2016a; Griffiths et al., 2016; Grob et al., 2011; Johnson et al., 2014; Ross et al., 2016) and tools to understand psychosis…”

“…(and the preceding Abnormal Mental States (APZ) questionnaire) have been widely used in behavioral and neuroimaging research of pharmacologically (Gouzoulis-Mayfrank et al., 2005; Griffiths et al., 2006, 2011; Vollenweider et al., 1998) as well as non-pharmacologically induced altered states of…”

“, 2016), altered social processing (Preller et al., 2016), visual imagery (Kaelen et al.”

“An accepted clinical definition of “paranoia” is “unfounded fears that others intend harm to the individual” (Freeman et al., 2015).”

“…Tagliazucchi et al., 2016), altered social processing (Preller et al., 2016), visual imagery (Kaelen et al., 2016), changes in emotional experience (Kaelen et al., 2015; Kraehenmann et al., 2015), personality change (Carhart-Harris et al., 2016b; Lebedev et al., 2016; MacLean et al., 2011),…”

“…has revived their investigation as therapeutic agents (Bogenschutz et al., 2015; Carhart-Harris et al., 2012, 2016a; Griffiths et al., 2016; Grob et al., 2011; Johnson et al., 2014; Ross et al., 2016) and tools to understand psychosis (Schmid et al., 2015; Vollenweider et al., 1998, 2007).”

“, 2006, 2011) or spiritual (Kometer et al., 2015) experiences, changes in self-referential processing or “ego dissolution” (Carhart-Harris et al.”

“…or “ego dissolution” (Carhart-Harris et al., 2014; Tagliazucchi et al., 2016), altered social processing (Preller et al., 2016), visual imagery (Kaelen et al., 2016), changes in emotional experience (Kaelen et al., 2015; Kraehenmann et al., 2015), personality change (Carhart-Harris et al.,…”

“Many other instruments were either used or developed to assess various aspects of subjective experience of hallucinogens, including the Linton-Langs questionnaire (Linton and Langs, 1962), the Abramson questionnaire (Abramson, 1960), the Phenomenology of Consciousness Inventory (Pekala, 1986), the Minnesota Multiphasi…”

“No items from the MEQ43 were included in the present analysis.”

“…two most widely used questionnaire instruments assessing the subjective effects of classic hallucinogens are the Hallucinogen Rating Scale (HRS) (Strassman, 1995; Strassman et al., 1994) and the various forms of Dittrich’s Altered States of Consciousness questionnaires (Dittrich, 1975, 1998;…”

“…exceedingly rare ( 0.001% of healthy individuals, and 0.002% of individuals undergoing therapy), however this summary must be viewed tentatively, given numerous limitations including, for example, that none of the reporting investigators had conducted follow-up with their patients (Novak, 1997).”

“However, the review noted that emergency department reports (e.g. McCabe, 1977; Taylor et al., 1970) are limited by uncertainty of substance ingested and unknown mental state of the patient prior to putative ingestion of a psychoactive substance.”

“…used in behavioral and neuroimaging research of pharmacologically (Gouzoulis-Mayfrank et al., 2005; Griffiths et al., 2006, 2011; Vollenweider et al., 1998) as well as non-pharmacologically induced altered states of consciousness (Hübner, 2007; Kjellgren et al., 2004; Walach and Kaseberg, 1998).”

“…performing a series of multiple-group confirmatory factor analyses, adding more constraints in each sequential model for parameters to be equal across groups and then testing to see whether model fit improves or degrades across sequential models (Kline, 2005; Lomax, 1983; Widaman and Reise, 1997).”

“…were either used or developed to assess various aspects of subjective experience of hallucinogens, including the Linton-Langs questionnaire (Linton and Langs, 1962), the Abramson questionnaire (Abramson, 1960), the Phenomenology of Consciousness Inventory (Pekala, 1986), the Minnesota…”

“Additional categories of challenging experience have been suggested in the literature, such as the experience of karmic or “astral” experiences, experience of “kundalini” energy, or the experience of such phenomena as age regression (McCabe, 1977).”

“…used in behavioral and neuroimaging research of pharmacologically (Gouzoulis-Mayfrank et al., 2005; Griffiths et al., 2006, 2011; Vollenweider et al., 1998) as well as non-pharmacologically induced altered states of consciousness (Hübner, 2007; Kjellgren et al., 2004; Walach and Kaseberg, 1998).”

“…aspects of subjective experience of hallucinogens, including the Linton-Langs questionnaire (Linton and Langs, 1962), the Abramson questionnaire (Abramson, 1960), the Phenomenology of Consciousness Inventory (Pekala, 1986), the Minnesota Multiphasic Personality Inventory (Belleville, 1956), the…”

“Recent work has sought to develop and validate a measure that is sensitive to difficult or challenging psychedelic experiences (Barrett et al., 2016; Carbonaro et al., 2016) and there is some evidence that the intensity of such experiences is predictive of positive long-term outcomes, whereas the duration of struggle…”

“, 2006) (although acute panic can occur (Barrett et al., 2016; Carbonaro et al., 2016)), yet there is increasing evidence that anxiety can be significantly reduced for a prolonged period after a therapeutically mediated psychedelic drug experience (Gasser et al.”

“More specifically, whereas we saw a trend relationship between challenging experience under a psychedelic and less of an increase in psychological well-being 2 weeks later, others have found evidence that challenging experiences can be therapeutically beneficial (Barrett et al., 2016; Carbonaro et al., 2016).”

“The Challenging Experience Questionnaire (CEQ) (Barrett et al., 2016) contains 30 items leading to a total score and seven subscales scores (i.”

“Email: leor.roseman13@imperial.ac.uk outcomes, thus suggesting that CE might be counter-therapeutic and perhaps even iatrogenic (Barrett et al., 2016; Carbonaro et al., 2016; Haijen et al., 2018; Roseman et al., 2017), although there are some contradictory findings in this regard, suggesting a more…”

“It is also possible that other aspects of the acute psilocybin experience, such as challenging (Barrett et al., 2016) or emotional breakthrough experiences (Roseman et al., 2019), are more influential in explaining long-term changes of psilocybin-assisted psychotherapy.”

“However, especially in unsafe settings, psychedelics can also cause “bad trips” involving intense physical and psychological distress [160].”

“Adverse events assessments during the medication visit included spontaneous participant self-report, events observed by clinicians, and symptoms derived from the Challenging Experiences Questionnaire (ChEQ) [33] administered the next day.”

“Construct Validity To assess construct validity, bivariate Pearson correlations were calculated between COMS scores, self-constructed items on participant and facilitator-connectedness, and the subscales of validated subjective experience measures taken at each ceremony (IF, PESC, MEQ, CEQ, ASC-VE).”

“The use of psychedelics, particularly in uncontrolled circumstances, is associated with acute adverse events (AEs) such as anxiety, panic, dysphoria, paranoia, and/or dangerous behaviors (Barrett et al., 2016; Johnson et al., 2008); such events may contribute to enduring psychological problems (Carbonaro et al.”

“The phenomenology of the acute experience includes fear, grief, feelings of insanity, para-noia, isolation, death, physical distress, confusing and troubling visions [13, 14].”

“Although mystical-type experiences are often occasioned by ingesting a psychedelic substance, challenging affective, physiological, and cognitive experiences also sometimes occurs (Barrett et al., 2016, 2017).”

“After drug effects had subsided on each dosing day, participants completed the Mystical Experience Questionnaire-30 (MEQ-30) (Barrett et al., 2015) and the Challenging Experience Questionnaire (CEQ) (Barrett et al., 2016) to retrospectively rate peak acute drug effects.”

“In addition, people sometimes describe a strong fear that they are dying or going insane (Barrett et al., 2016).”

“A sense of not being in control of the experience may also manifest, which in some cases may be reflected in the temporary feeling of losing one’s mind or going insane (Barrett et al., 2016).”

“These challenging experiences(1) (42, 52, 53) are often characterized by extreme fear or panic, and can involve frightening imagery, unsettling body sensations, and the apprehension of immediate threat.”

“In this conceptualization, the anxiety or panic that can occur during an adverse encounter with psychedelics can be equated with instances of unmitigated fear (Barrett et al., 2016).”

“tually significant psychedelic experiences (35,41).”

“Studies have reported mixed results for the relationship between challenging experiences and long-term psychological outcome (Barrett et al., 2016; Carbonaro et al., 2016; Haijen et al., 2018).”

“…elevated cortical 5-HT2AR expression (Frokjaer et al., 2008), predicts thought disturbance, blackout and challenging experiences under psychedelics (Barrett et al., 2016, 2017; Lienert and Netter, 1996; although see Studerus et al., 2012) and yet may be reduced after psychedelic therapy (Erritzoe…”

“We included the Challenging Experiences Questionnaire (CEQ), a 26-item self-report measure developed to assess the intensity of challenging experiences one might have after taking a hallucinogen (Barrett et al., 2016).”

“Seven subscales and a total score were expressed as percentage ofmaximum possible scores (Barrett et al. 2016).”

“60 In the long term, such experiences can also cause ontological shocks, resulting in a dramatic shift in one’s religious and spiritual worldviews.”

“Challenging experience questionnaire (CEQ; Barrett et al., 2016).”

“Responses from a total of 981 participants who provided useable data for an online survey of challenging experiences with psilocybin mushrooms (Barrett et al., 2016) were included in the current analysis.”

“The Challenging Experience Questionnaire (CEQ) is a 26-item measure assessing seven dimensions of psychedelic-occasioned challenging experiences: grief, fear, death, insanity, isolation, physical distress, and paranoia, with each dimension comprising a CEQ subscale (Barrett et al., 2016).”

“The 26-item Challenging Experience Questionnaire (CEQ) assessed a variety of difficult experiences that could arise during the psilocybin session, comprised of seven factors: grief, fear, death, insanity, isolation, physical distress, and paranoia (49).”

“…complete mystical experience (scored as reaching ⩾60% on each of the subscales of the Mystical Experience Questionnaire, MEQ-30; Barrett et al., 2015) with around 37% having challenging experiences (measured by the Challenging Experience Questionnaire; Barrett et al., 2016; Davis et al., 2018a).”

“These are consistent with previous reports of the nature of adverse reactions to psilocybin and other psychedelics and have been discussed in depth elsewhere (Barrett et al., 2016; Van Amsterdam et al., 2011).”

“…and challenging psychological experiences increase at higher doses (Griffiths et al., 2011; Studerus et al., 2012), it would be informative to measure these experiences (Barrett et al., 2016; Carbonaro et al., 2016) future studies to examine their impact on the rate of mystical experience.”

“Awe has been proposed as a potential mechanism of action underlying the effects of classic psychedelic-assisted psychotherapy (42) and theoretically overlaps with mystical experiences (43), the small self and ego dissolution (44) and challenging experiences (45) under psychedelics.”

“…with such "challenging experiences" encompassing feelings such as intense grief, fear, death, insanity, isolation, physical distress, and paranoia (Barrett et al., 2016) (note that the specificity of the term "challenging experiences" means they are not simply equivalent to the negative…”

“Some researchers have argued that MEs cannot be measured on a continuous linear scale but instead involve an inflection or transition point into “complete” MEs that appears to be strongly dose-dependent (Barrett et al., 2015; Griffiths et al., 2011). Validated criteria and thresholds for determining the occurrence of…”

“Psychedelics do pose a risk of psychologically unpleasant acute experiences, and subjective responses remain unpredictable (Barrett et al., 2016; Byock, 2018; Russ et al., 2019).”

“…AVE and ACE with CEQ and EBI scores, respectively, lend further support to the construct validity of the APEQ, and add some clarity to the role of challenging (Barrett et al., 2016) and emotional breakthrough experiences (Roseman et al., 2019) in determining longer-term responses to psychedelics.”

“” Previous research (Barrett et al., 2016) has found that the measure produces seven subscales: (1) fear, (2) grief, (3) physical distress, (4) sanity, (5) isolation, (6) death, and (7) paranoia.”

“Although subsequent validation in prospective studies generally follows initial investigations 103 , criterion outcomes have been measured using retrospective indices of change 3,9,21,78,79,98 , which are more likely than prospective measures to be vulnerable to placebo and expectancy effects.”

“High ratings for CE have been associated with both worsened (Barrett et al., 2016; Carbonaro et al., 2016; Haijen et al., 2018; Roseman et al., 2018) and improved long-term mental health outcomes (Carbonaro et al., 2016; Davis et al., 2021b).”

“Reported negative outcomes were mostly related to emotional states as well as some cognitive functions and appeared largely similar to those observed from recreational use (Barrett et al., 2016; Bienemann et al., 2020; Carbonaro et al., 2016; Gashi et al., 2021; Soares et al., 2022).”

“These experiences also relate to their category of insanity, which included the item “ I was afraid that the state I was in would last forever ” (Barrett et al., 2016, p. 22).”

“…2019), the Mystical Type Experience Questionnaire (Hood 1975, see also Siegel and Emmert-Aronson 2021), the Psychological Insight Questionnaire (Peill et al. 2022), the Challenging Experience Questionnaire (Barrett et al. 2016), and the Altered States of Consciousness scale (Studerus et al. 2010).”

“Negative experiences (so-called bad trips) that are induced by full doses of psychedelics, including severe anxiety, negative feelings, or panic attacks, are sometimes referred to as “challenging experiences” to indicate that these experiences may have some therapeutic value (Barrett et al. 2016).”

“org 6 described in terms of psychostimulant effects (20, 29), whereas challenging, emotional breakthrough, and mystical-type experiences appear to underlie the therapeutic outcomes of the classic tryptamine psychedelic psilocybin (16, 66, 67).”

“Without adequate support, subsequent adverse reactions can escalate into, for example, panic attacks, paranoia, aggression, self-harming or accidents, as demonstrated in both the present survey and previous literature (Barrett et al., 2016; Carbonaro et al., 2016; Strassman, 1984).”

“The association of the subjective experience (Emotional Breakthrough Inventory, EBI; 11D-Altered States of Consciousness, 11D-ASC; Challenging Experience Questionnaire, CEQ) (Barrett et al., 2016; Roseman et al., 2019; Dittrich, 1998) with treatment outcomes is also investigated.”

“Case reports of persisting perceptual changes exist, though these are rare (54, 55).”

“…of psychosocial health, we suggest a set of constructs for the assessment of AEs in clinical trials of PAT, focusing primarily on time points preceding and following the acute dosing session (for characterizations of AEs during the dosing session, see Barrett et al. (2016), Schlag et al. (2022)).”

“Generally, less AEs were observed in this study when compared to psychedelic use in uncontrolled circumstances (Barrett et al., 2016; Breeksema et al., 2022; Johnson et al., 2008), reinforcing 5-MeO-DMT administration is safer in a clinical setting.”

“As such it has been suggested that therapeutic interventions should focus on reducing the duration of a challenging experience rather than reducing its peak difficulty (Barrett et al., 2016; Carbonaro et al., 2016).”

“The CEQ psychometric evaluation was performed on secondary and retrospective data from an online survey of 2085 people who had challenging experiences with psilocybin, The Bad Trip Survey (Carbonaro et al. 2016).”

“Challenging Experience Questionnaire (CEQ) The CEQ was developed using an Internet survey of those reporting a wide range of challenging experiences while using psilocybin and has been shown to have good internal consistency and external reliability [24].”

“Correlations between GCMQ scales, APEQ main scales (Acceptance and Avoidance), APEQ ancillary scales (Introspection and Interaction), EBI scores, CEQ total scores, and OBN scores are presented in Table 9.”

“Barrett et al. (2016) created the Challenging Experience Questionnaire (CEQ), which is designed to quantify challenging experiences under the influence of psychedelics (Barrett et al., 2016).”

“Other psychometric scales such as the Altered States of Consciousness Rating Scale (Dittrich, 1998), Hallucinogenic Rating Scale (Strassman et al., 1994), Hood Mysticism Scale (Hood, 1975), Challenging Experience Questionnaire (Barrett et al., 2016), Psychological Insight Questionnaire (Davis et al., 2021), and Emotio…”

“We included the 26-item Challenging Experiences Questionnaire (CEQ) to examine the acute challenging psychological or physical experiences that could occur after taking a classic hallucinogen (Barrett et al. 2016).”

“Convergent and divergent evidence was evaluated by inspecting the correlations between PPS scores and validated measures that were expected to be positively correlated with psychedelic preparedness (e.g. EBI, MEQ), and measures that were expected to be negatively correlated with psychedelic preparedness (e.g. CEQ).”

“For example, Barrett et al. [101] argue that while acute adverse psychological reactions to psychedelics are usually benign in controlled settings with proper screening, preparation, and support, they remain a safety concern in uncontrolled settings.”

“15 There has been little systematic research on negative psy-chedelic experiences or “ bad trips, ” the de fi nition of which remains unclear.”

“The Challenging Experience Questionnaire (CEQ) is a widely used self-report instrument that measures challenging experiences during psychedelic sessions.”

“, 2021) and feelings of intense anxiety are often found in therapeutic settings during a portion of the session (Barrett et al., 2016; Griffiths et al., 2006).”

“…measures of the acute experience: the mystical experience questionnaire (MEQ; Barrett et al., 2015), the ego dissolution inventory (EDI; Nour et al., 2016), the emotional breakthrough inventory (EBI; Roseman et al., 2019), and the challenging experience questionnaire (CEQ; Barrett et al., 2016).”

“For averaged scores, results were highly convergent with the exception of CEQ Death exhibiting a significant indirect effect (Supplementary Table S8).”