Altered states of consciousness in Danish healthy volunteers and recreational users of psilocybin and the possible impact of setting and intention: Danish validation of the five-dimensional altered states of consciousness questionnaire

Abstract

Background:

Psychedelic substances reliably induce marked altered states of consciousness (ASC), which may be important for lasting effects and clinical outcomes of psychedelic intervention. Several instruments are available to measure the acute psychedelic experience, of which the Five Dimensional Altered States of Consciousness Questionnaire (5D-ASC) is commonly used. The questionnaire can be scored and analyzed as having five dimensions or 11 subscales, but the two have not been evaluated with comparable factor analysis methods.

Methods:

The Danish translation of the 5D-ASC was completed by one sample of healthy volunteers receiving psilocybin in a laboratory setting (N = 47) and one sample of recreative users5D-ASC of psychedelics (N = 550), who reported retrospectively through an online survey based on their most recent experience with psilocybin. We calculated internal consistency measures of Cronbach’s alpha and McDonald’s omega, conducted a confirmatory factor analysis of the previously suggested factor structures, and tested for possible associations between the 5D-ASC total scores and dose, setting, and intention. For the 11 subscales, we reported omega-sem (composite reliability) using the parameters of the fitted confirmatory factor analyses model.

Results:

Confirmatory factor analysis showed that the 11 subscales had a good fit to data and showed a better fit compared to the originally proposed five-dimensional solution and good internal consistencies. We further found that the 5D-ASC total scores correlated positively with the dose in the recreative sample. We found no correlations between 5D-ASC total scores and intention or setting.

Discussion:

We find the Danish 5D-ASC to be a valid tool for measuring ASC among Danish-speaking individuals.

Keywords

Altered states of consciousness psilocybin LSD psychedelics

Introduction

Classical psychedelic compounds such as psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltryptamine act primarily via serotonin 2A receptor subtype (5-HT_2A) agonism in the brain (Becker et al., 2023; Madsen et al., 2019; Valle et al., 2016). They can dose dependently induce an altered state of consciousness characterized by changes in sensory perception, cognition, mood, meaning attribution, and the sense of self, time, and space (Nichols, 2004, 2016).

A growing body of both naturalistic and clinical evidence suggests that classical psychedelics can have beneficial long-term effects on general well-being (Bouso et al., 2012; Schmid, 2018), personality openness (MacLean et al., 2012), mood, attitude, mindfulness (Søndergaard et al., 2023), and behavior (Griffiths et al., 2008, 2011, 2018; Madsen et al., 2020). They have also shown promising results in the treatment of psychiatric illnesses such as alcohol use disorder (Bogenschutz et al., 2015, 2022), obsessive-compulsive disorder (Moreno et al., 2006), anxiety, and depression (Carhart-Harris et al., 2016, 2021; Davis et al., 2021; Goodwin et al., 2022; Grob et al., 2011; Raison et al., 2023; Ross et al., 2016; von Rotz et al., 2023), albeit with considerable risk of bias (Hovmand et al., 2023). Individual variation in the intensity of psychedelic-induced altered state has been shown to predict the magnitude of changes in the previously mentioned parameters after intake with greater intensity of altered state of consciousness associated with more favorable outcomes (Bogenschutz et al., 2015; Garcia-Romeu et al., 2014; Griffiths et al., 2008; Holze et al., 2023; Roseman et al., 2018). The content of a psychedelic experience has further been shown to be dependent on the extra-pharmacological factors, for example, set (the user’s mindset prior to the psychedelic experience) and setting (the physical and social environment in which the user has the experience (Hartogsohn, 2016; Hovmand et al., 2024a).

Given the purported importance of the psychedelic-induced altered state of consciousness, it is important to develop and evaluate research instruments that can measure it in a psychometrically sound manner. A recent review of patient-reported outcome measures available to assess one or more aspects of the acute psychedelic experience found that the 94-item Five Dimensional Altered States of Conscious Questionnaire (5D-ASC) had been utilized in most trials (54 of 93 trials, ~58%) (Hovmand et al., 2023b).

The 5D-ASC was developed and published by Dittrich (1998) and is designed to assess the characteristics of an altered state of consciousness induced by both pharmacological (e.g., classical psychedelics or MDMA), and non-pharmacological methods (e.g., sensory deprivation or meditation) (Dittrich, 1998). The 5D-ASC is the second and most recent revision of the questionnaire Abnormer Psychischer Zustand (APZ, Eng: Altered State of Consciousness) (Dittrich, 1975, 1998) and its first revision, the OAV (the abbreviation OAV stands for the German names of the three dimensions Oceanic Boundlessness (OBN), Dread of Ego Dissolution (DED), and Visual Restructuralization (VRS)) (Bodmer, 1989).

There are two commonly applied ways to score and analyze the 5D-ASC. The first way to analyze the 5D-ASC comprises five dimensions based on all 94 items. The ratings of 66 items are combined to form three core dimensions (together described as the OAV) which are believed to be shared by ASC experiences across methods of induction: (1) OBN (2) DED, and (3) VRS. The remaining 28 items constitute two supplementary dimensions which are believed to be dependent on the method of induction: (4) Auditory Alterations (AUA) and (5) Vigilance Reduction (VIR) (Dittrich, 2006, 2010). The second way to analyze the 5D-ASC comprises 11 subscales based on 42 of the 66 items that constitute the OAV, leaving out the remaining 52 items from the full 5D-ASC. The ratings of these 42 items are combined to form 11 subscales: (1) Experience of Unity (EOU), (2) Spiritual Experience (SE), (3) Blissful State (BS), (4) Insightfulness (I), (5) Disembodiment (D), (6) Impaired Control and Cognition (ICC), (7) Anxiety (A), (8) Complex Imagery (CI), (9) Elementary Imagery (EI), (10) Audio-Visual Synesthesia (AVS), and (11) Changed Meaning of Percepts (CMP) (Studerus et al., 2010). These subscales constitute narrower constructs that are at a lower level of the construct hierarchy than the OBN, DED, and VRS dimensions originally proposed by Dittrich (1998). The 11 subscales were therefore intended to complement rather than replace Dittrich’s proposed dimensions. They are sometimes described under the acronym “11D-ASC.” However, this is wrong and misleading as they are subscales and not dimensions. The 5D-ASC and its previous iterations were originally developed in German (Dittrich, 1975) and have been translated into English (Dittrich, 1985a). However, it has yet to be psychometrically evaluated in its entirety in both English and Danish.

Here, we report a validation of our Danish translation of the 5D-ASC. The complete 5D-ASC was administered to healthy volunteers who had received psilocybin in a laboratory setting and to recreational users of psilocybin, retrospectively reporting on their most recent psychedelic experience with psilocybin. In these two populations, we examine (1) whether the Danish ASC demonstrates adequate reliability; (2) whether the originally proposed five-dimensional solution of Dittrich et al. or the 11 subscales described by Studerus et al. show a better fit to the data; and (3) the associations between 5D-ASC total scores and dose, setting, and intention.

We hypothesize that the Danish 5D-ASC questionnaire will have adequate internal reliability both when analyzed with five dimensions and 11 subscales, and the 11 subscales structure will have a better fit compared to the five dimensions structure. We further hypothesize that 5D-ASC total scores will increase dose dependently and that a therapeutic setting and intention will be associated with higher 5D-ASC total scores.

Methods

Procedure and participants

The data utilized in this paper were collected in the following two studies:

Study I

Between March 2017 and February 2022, 47 healthy volunteers recruited from the general population participated in a study on the neurobiological effects of psilocybin. They were administered weight-adjusted dosages of 3–30 mg of psilocybin under single-blind or unblinded conditions. On the intervention day, after the psychedelic effects of psilocybin had subsided, participants completed the 5D-ASC. Seven of the participants were administered psilocybin twice at least 12 months apart and were therefore also administered the 5D-ASC on two occasions. See the primary papers for further details (Madsen et al., 2019, 2020, 2021). Exclusion criteria were as follows: (1) present or previous personal or family (first-degree relatives) history of psychiatric disease (DSM axis 1 or WHO ICD-10 diagnostic classification), including substance misuse disorder. (2) Present or previous neurological condition/disease, significant somatic disease, or any intake of drugs suspected to influence test results, (3) non-fluent Danish language skills, (4) vision or hearing impairment, (5) learning disability, (6) pregnancy, (7) breastfeeding, (8) MRI contraindications, (9) alcohol or drug abuse, (10) allergy to test drugs, (11) significant exposure to radiation within the past year (e.g., medical imaging investigations), (12) intake of QT-prolonging medication or electrocardiogram (ECG) results indicative of heart disease, (13) history of significant adverse response to a hallucinogenic drug, (14) use of hallucinogenic drugs less than 6 months prior to inclusion, (15) blood donation less than 3 months preceding project participation, (16) body weight less than 50 kg, and (17) low plasma ferritin levels (<12 μg/L). The study was approved by the Capital Region Ethical Committee (journal identifier: H-16028698, amendments: 56023, 56967, 57974, 59673, 60437, 62255) and Danish Medicines Agency (EudraCT identifier: 2016-004000-61, amendments: 2017014166, 2017082837, and 2018023295).

Study II

Between November 2022 and January 2023, 550 recreative users of psilocybin participated in an online survey on recreative use of psilocybin and self-reported the 5D-ASC. This survey specifically enquired about their most recent psychedelic experience with psilocybin. All participants endorsed that they had a clear memory of this experience. Participants were mainly recruited through paid ads on Facebook targeted at the general adult population and via Danish-language social media groups and websites related to psychedelics. Inclusion criteria were as follows: being at least 18 years of age, being able to read, speak, and understand Danish fluently, and having tried psilocybin at least once. Experiences of psychedelic microdosing were not included. To ensure complete anonymity, no personal information was collected, as defined by the Danish Data Protection legislation. We collected informed consent from all participants. The data management system and online survey tool LimeSurvey (2012) were used to collect the data. The survey was approved by the Region Zealand Data Protection Agency (registration number REG-051-2022). The study was further exempt from prior external ethical review as it did not fulfill any of the conditions set forth by the Region Zealand Ethical Committee.

Measures

5D-ASC

We used a Danish translation of the 5D-ASC produced by the Neurobiology Research Unit (NRU) at Rigshospitalet, Copenhagen, Denmark. The edition of the 5D-ASC that was translated into Danish was the edition translated from German by Drs. Felix Hasler and Rael Cahn. The Danish version was translated by three English-fluent, native Danish speakers to reach a consensus translation by the last author of the present paper (DSS). This consensus translation was subsequently back-translated to English by a native Danish–English bilingual speaker. The original and back-translated English versions were compared by a native English speaker (PMF) and uncertainties were resolved by PMF and DSS to reach an agreement on the final wording of the items in Danish.

The 5D-ASC is a self-report questionnaire used to assess altered states of consciousness (ASC) related to a discrete event, such as one induced by psilocybin. The 5D-ASC consists of 94 items which are rated on a 100-point visual analog (VAS) scale (0 = NO, not more than usual; 100 = YES, very much more than usual). We calculated total scores for the five dimensions and the 11 subscales by calculating the sums of item scores on the included items. The Danish translation of the 5D-ASC is presented as supplementary information to the present paper.

Additional measures

Participants in Study II further answered questions regarding the self-estimated dose of psilocybin ingested (small, moderate, high, or very high), the setting of the experience (at home; in nature; in another home; at a party or a festival; at a retreat or the place my therapist/trip sitter works from; another place), and the intention for the experience (to have fun or have an exciting experience; therapeutic intention or to work on a specific problem; the intention of self-enhancement or to enhance the relationship to another person the participant had the experience with; to have a spiritual or religious experience; no specific intention; or other intention).

Statistical analyses

We undertook all data processing and analyses using R 4.3.0 (Already Tomorrow) and RStudio 2022.07.2+576 (RStudio, 2019), including the psych 2.1.9 (Revelle, 2007), lavaan 0.6–9 (Rosseel, 2012), semTools, and DescTools R packages. R scripts are available from the first author upon request. The 5D-ASC employs VAS-type responses with 100 increments, and all data were treated as continuous data.

To address hypothesis 1 which concerned reliability, we assessed the internal validity and reliability of the Danish 5D-ASC by calculating Cronbach’s alpha (α), McDonald’s hierarchical omega (ωh), and the total omega (ωtotal). ωh is an estimate of the general factor saturation of a test and ωh is an estimate of the total reliability of a test (Revelle and Zinbarg, 2009). For the 11 subscales, we did not calculate ωh and ωtotal due to most having only three items, but instead reported the omega-sem (composite reliability) using the parameters of the fitted CFA model. These estimates were used as indicators of the internal consistency for both the total score and the individual dimensions/subscales of the Danish 5D-ASC. Cronbach’s alpha above 0.70 were considered satisfactory (Bland, 1997; Hair, 2016), and so were ωh above 0.65 and ωtotal above 0.80 (Nájera Catalán, 2019). We also calculated the described reliability estimates for the two studies combined.

To address hypothesis 2 which concerned factor structure, we carried out confirmatory factor analyses (CFA) of the Danish 5D-ASC. We used the lavaan R (Rosseel, 2012) package and the MLM estimator as we treated the data as continuous. We calculated, as recommended by Kline (2015), the comparative fit index (CFI), the Tucker-Lewis index (TLI), the root mean square error of approximation (RMSEA), the standardized root mean square residual (SRMR), and the degrees of freedom (df) (Kline, 2015). We utilized the criteria set forth by Hu and Bentler, which suggest that an RMSEA smaller than 0.06, an SRMR smaller than 0.08, and a CFI and TLI larger than 0.95 indicate relatively good model-data fit (Hu and Bentler, 2009). The Chi-square fit statistic is affected by large samples and is therefore usually evaluated as the ratio of the Chi-square statistic to the respective degrees of freedom (χ²/df) (Wheaton et al., 1977). A ratio of smaller than 2 indicates a superior fit data (Cole, 1987).

To address hypothesis 3 which concerned dose dependence and associations with setting and intention, we examined whether 5D-ASC total scores increased in a dose-dependent manner by calculating the Pearson correlation coefficients between 5D-ASC total scores and self-estimated dosage of psilocybin (Study II). We further examined Pearson correlation coefficients between 5D-ASC total scores and the setting and intention (Study II). Here, we coded answers that endorsed the question as 1 and answers that did not as 0 to calculate correlations. To correct for multiple tests (five tests), we performed a Bonferroni correction to adjust our significance threshold to maintain α = 0.05, resulting in an adjusted significance level of p < 0.01.

Lastly, we examined Pearson correlation coefficients between 5D-ASC total scores and the intention of the psychedelic experience (Study II). Again, we coded answers as 1 or 0 and corrected for multiple tests (five tests) by performing a Bonferroni correction, resulting in an adjusted significance level of p < 0.01.

Results

Descriptive statistics

Table 1 presents participant characteristics across the two studies.

Table 1.

Descriptive statistics.

Demographics	Study I (N = 47)		Study II (N = 550)
Demographics	N	%	N	%
Age	33.55 (8.7)		40.1 (12.0)
Gender
Female	18	38.3	176	32.0
Male	31	61.7	365	66.4
Non-binary and other	NA	NA	9	1.6
Education
Elementary school	6	12.7	91	16.5
Secondary school	0	0	58	10.5
Vocational school	0	0	76	13.8
Short post-secondary education	2	4.2	103	18.7
Bachelor’s degree	5	10.6	38	6.9
Long post-secondary education	33	70.2	184	33.5
History of psychiatric illness or psychiatric treatment
Yes	0	0	322	38.9
No	47	100	228	41.4
Frequency of illicit drug use (including psychedelics) at present
Never	NA	NA	113	20.5
Monthly or less	NA	NA	321	58.4
Weekly	NA	NA	63	11.5
Daily	NA	NA	53	9.6
Intentions
Fun or exciting experience	NA	NA	230	41.8
Therapeutic	NA	NA	126	22.9
Self enhancement	NA	NA	85	15.5
Spiritual or religious	NA	NA	64	11.63
No specific	NA	NA	45	8.2
Settings
Other	NA	NA	297	54
Home	NA	NA	196	35.6
Party or festival	NA	NA	41	7.46
Professional	NA	NA	16	2.9

Data are presented as n (%) or mean (SD).

NA: not asked for.

5DASC_Table_1.docx

Study I

The participants were administered an average dose of 19.5 (SD = 4.3) mg psilocybin. The total score on the 5D-ASC was 4067.99 (SD = 2989.38), or 43.27% of the maximum total score of 9400 for the complete sample. The total score of the 11 subscales was 1311.61 (SD = 1003.84), or 31.22% of the maximum total score of 4200 for the complete sample. See Table 2 for details regarding scores on individual subscales.

Table 2.

Total score and score on individual subscales.

	Study 1		Study 2		Combined
5D-ASC
Total	4067.99	(2989.38)	2563.01	(1282.2)	2748.08	(1666.43)
Oceanic boundlessness	2578.54	(1887.46)	1212.73	(622.09)	1380.7	(986.86)
Dread of ego dissolution	303.59	(344.78)	256.05	(309.34)	261.89	(314)
Visual restructuralization	672.93	(535.18)	722.47	(384.8)	716.38	(406.09)
Auditory alterations	158.78	(212.05)	164.7	(220.79)	163.98	(219.57)
Vigilance reduction	354.14	(239.47)	207.04	(176.72)	225.13	(191.55)
11 subscales
Total	1311.61	(1003.84)	1343.63	(676.81)	1339.69	(724.05)
Experience of unity	197.99	(179.67)	218.35	(148.73)	215.84	(152.85)
Spiritual experience	77.83	(94.32)	114.49	(85.33)	109.98	(87.24)
Blissful state	136.07	(111.84)	161.49	(92.47)	158.36	(95.33)
Insightfulness	106.56	(96.94)	141.6	(86.82)	137.29	(88.79)
Disembodiment	124.03	(111.55)	80.3	80.58	85.68	(86.01)
Impaired control and cognition	133.45	(150.38)	95.6	109.84	100.25	(116.12)
Anxiety	64.87	(95)	102.22	35.5	71.77	(101.32)
Complex imagery	137.24	(115.75)	128.32	89.64	129.41	(93.18)
Elementary imagery	155.53	(123.46)	161.37	97.31	160.65	(100.8)
Audio-visual synesthesia	131.29	(116.03)	96.93	94.54	101.16	(97.99)
Changed meaning of percepts	46.8	(60.22)	72.46	58.24	69.3	(59.04)

Data are presented as means and (SD).

Study II

The participants remembered the reference experience clearly (all endorsed that they had a good recall of the experience). The total score on the 5D-ASC was 2563.01 (SD = 1282.2), or 27.3% of the maximum total score of 9400 for the complete sample. The total score of the 11 subscales was 1343.63 (SD = 676.81), or 32.0% of the maximum total score of 4200 for the complete sample. See Table 2 for details regarding scale reliability estimates.

5DASC_Table_2.docx

Internal consistency of the Danish 5D-ASC and the 11 subscales

The internal consistency of the 5D-ASC total score as well as for the individual dimensions was satisfactory across studies. The internal consistency of the total score of the 11 subscales and the individual subscales was also satisfactory across subscales. See Table 3 for details regarding internal consistency total score and individual subscales.

Table 3.

Scale reliabilities.

	Study 1			Study 2			Studies combined
	α (95% CI)	ωh	ωtotal	α (95% CI)	ωh	ωtotal	α (95% CI)	ωh	ωtotal
5D-ASC
Total	0.98 (0.98, 0.99)	0.53	0.97	0.96 (960, 0.97)	0.53	0.9	0.96 (960, 0.98)	0.53	0.97
Oceanic boundlessness	0.98 (0.97, 0.98)	0.91	0.98	0.95 (0.94, 0.95)	0.76	0.96	0.95 (0.95, 0.96)	0.76	0.96
Dread of ego dissolution	0.94 (0.93, 0.98)	0.67	96	0.93 (0.92, 0.94)	0.78	0.95	0.93 (0.92, 0.94)	0.76	0.95
Visual restructuralization	0.96 (0.94, 0.97)	0.8	0.97	0.89 (0.88, 0.91)	0.64	0.92	0.9 (0.91, 0.92)	0.67	0.93
Auditory alterations	0.89 (0.85, 0.92)	0.73	0.92	0.91 (0.9, 0.92)	0.74	0.93	0.91 (0.9, 0.92)	0.77	0.92
Vigilance reduction	0.85 (0.8, 0.9)	0.53	0.90.	0.83 (0.81, 0.85)	0.73	0.88	0.83 (0.83, 0.86)	0.72	0.89
11 subscales	α (95% CI)	omega-sem		α (95% CI)	omega-sem		α (95% CI)	omega-sem
Total	0.97 (0.96, 0.98)			0.93 (0.92, 0.94)			0.94 (0.93, 0.95)
Experience of unity	0.92 (0.9, 0.95)	0.95		0.87 (0.85, 0.89)	0.87		0.88 (0.87, 0.9)	0.88
Spiritual experience	0.86 (0.81, 0.92)	0.88		0.71 (0.67, 0.75)	0.71		0.74 (0.7, 0.77)	0.74
Blissful state	0.9 (0.87, 0.94)	0.90		0.83 (0.81, 0.86)	0.84		0.84 (0.82, 0.87)	0.85
Insightfulness	0.78 (0.7, 0.87)	0.89		0.77 (0.73, 0.8)	0.76		0.77 (0.74, 0.8)	0.77
Disembodiment	0.87 (0.81, 0.92)	0.90		0.81 (0.78, 0.84)	0.82		0.83 (0.8, 0.85)	0.84
Impaired control and cognition	0.85 (0.81, 0.9)	0.86		0.8 (0.78, 0.83)	0.80		0.81 (0.79, 0.84)	0.82
Anxiety	0.85 (0.74, 0.87)	0.81		0.84 (0.82, 0.86)	0.86		0.84 (0.82, 0.86)	0.86
Complex imagery	0.9 (0.85, 0.94)	0.88		0.75 (0.72, 0.79)	0.76		0.78 (0.75, 0.81)	0.78
Elementary imagery	0.93 (0.9, 0.96)	0.93		0.83 (0.8, 0.85)	0.86		0.84 (0.82, 0.86)	0.87
Audio-visual synesthesia	0.89 (0.85, 0.93)	0.87		0.87 (0.85, 0.89)	0.87		0.87 (0.86, 0.89)	0.88
Changed meaning of percepts	0.68 (0.56, 0.8)	0.76		0.52 (0.45, 0.58)	0.66		0.54 (0.48, 0.6)	0.67

5DASC_Table_3.docx

Factor structure of the Danish 5D-ASC

The 11 subscales model had a better fit to data across studies and in the two studies combined on all parameters evaluated. In both studies, the RMSEA showed a good fit do data. The CFI and TLI showed a good fit do data in Study 1, but less in Study II and the two studies combined. The χ²/df ratio was good for the 11 subscales model in both studies. See Table 4 for the fit statistics for the factor structures for each of the two studies and the studies combined.

Table 4.

Fit statistics factor analysis.

Model	CFI	TLI	RMSEA	SRMR	χ²	df	χ²/df
Study I: (N = 54)
Eleven subscales model	1.000	1.025	0.0	0.094	391.386	764	0.51
Five dimensions model	0.990	0.990	0.086	0.083	6646.370	4267	1.5
Study II: (N = 550)
Eleven subscales model	0.898	0.886	0.054	0.060	1957.337	764	2.6
Five dimensions model	0.685	0.677	0.064	0.095	13520.071	4267	3.2
Combined: (N = 604)
Eleven subscales model	0.903	0.890	0.054	0.061	2147.179	764	2.8
Five dimensions model	0.688	0.681	0.065	0.098	15152.290	4267	3.6

Four different possible factor structures of the 5D-ASC, as tested among participants reporting on their reference experience.

N: number of unique experiences analyzed; CFI: comparative fit index; TLI: Tucker–Lewis index; RMSEA: root mean square error of approximation; SRMR: standardized root mean square residual; df: degrees of freedom.

5DASC_Table_4.docx

Dose dependence and dependence on intention and setting of the Danish 5D-ASC

Study II

We found a statistically significant positive correlation between self-reported dosage (low, medium, high, and very high) and the 5D-ASC total score (r = 0.19, p ⩽ 0.01). We also found a significant positive correlation between self-reported dosage (low, medium, high, and very high) and the total score on the 11 subscales total score (r = 0.18, p ⩽ 0.01).

There were no significant correlations between the 5D-ASC total scores when analyzed with five dimensions or 11 subscales and intention (self-enhancement, intention of having fun or having an exciting experience, no specific intention, a therapeutic intention, or spiritual intention) or setting (at home; in nature; in another home; at a party or a festival; at a retreat or the place my therapist/trip sitter works from; another place).

Discussion

In the present study, we found evidence of overall satisfactory internal consistency and construct validity of the Danish translation of the 5D-ASC both when analyzed with five dimensions and 11 subscales. This was found across the two studies separately and in the two studies combined. More specifically, we found the internal consistencies of the individual dimensions and the total scores of the 5D-ASC to be good to excellent in both studies and the studies combined, whereas this was the case for most, but not all of the 11 subscales.

We found according to our hypothesis that the 11 subscales structure (Studerus et al., 2010) had a better fit to the data than the five dimensions factor structure (Dittrich, 1985b). This is to the best of our knowledge the first time that the psychometric properties of the recently proposed 11 subscales structure have been directly compared to the five dimensions structure. Our study is also the first comparable factor analysis validation of the 11 subscales structure (Studerus et al., 2010). Importantly, our data suggest that the 11 subscales structure has superior psychometric qualities compared to the five dimensions structure. Analyzing the 5D-ASC with the 11 subscales only utilizes half of the items and omits the 28 items, which constitute the two supplementary dimensions AUA and VIR. It is, therefore, possible that an 11 subscales analysis fails to capture important information about the psychedelic-induced ASC, which is captured in a five dimensions analysis (e.g., item #4 “I heard single words without knowing where they came from” and item #48 “I heard music without knowing where it came from,” but instead only item #30 “I heard complete sentences without knowing where they came from”). We therefore suggest that future research investigate which 5D-ASC scoring (five dimensions or 11 subscales) is most sensitive to predict a favorable treatment outcome.

The 5D-ASC total scores increased in a dose-dependent manner in our recreative sample. This is in line with previous research that found the 5D-ASC to be dose dependent in laboratory samples (Hirschfeld and Schmidt, 2021; Liechti et al., 2017). We found no associations between the intensity of the altered state of consciousness as measured by the 5D-ASC and various self-reported intentions and settings. This is in contrast to findings from another measure of altered state of consciousness, the Revised Mystical Experience Questionnaire 30 (MEQ30), which in similar naturalistic research was found to be associated with intention (Haijen et al., 2018; Hovmand et al., 2024a). This tentatively suggests that the MEQ30, rather than the 5D-ASC assesses components of the ASC that are modifiable by prior intention. We are unaware of other studies investigating the association between 5D-ASC total scores and setting or intention.

Translating questionnaires between languages on potentially ambiguous topics such as ASC raises the possibility of phrasings being interpreted as incongruent between translations. Two different English translations of the 5D-ASC exist, both including at least two translation issues. Item #12 is in German “Ich empfand grenzenlose Freude,” which is translated to English as “I enjoyed boundless pleasure.” However, “Freude” is arguably not “pleasure” in English but instead “joy.” Our Danish version, “Jeg oplevede grænseløs nydelse eller fornøjelse,” was back-translated to “I experienced boundless pleasure or joy.” Item #42 is in German “Gegensätze und Widersprüche schienen sich aufzulösen,” which is translated to English as “Conflicts and contradictions seemed to dissolve.” However, “Gegensätze” is arguably not “conflicts,” but instead “opposites.” Our Danish version, “Konflikter og modsigelser syntes at opløse sig og forsvinde” was back-translated to “Conflicts and opposites seemed to dissolve.” As such, we view our Danish version as less liable to the translation inaccuracies present in the English translations.

A number of limitations of this validation study must be considered. The retrospective design of Study II is susceptible to recall bias. The participants were also, to a large extent, recruited through social media and forum websites dedicated to the discussion of psychedelics, which increases the risk of selection bias. Therefore, it is possible that the distribution of responses was biased toward more positive psychedelic experiences. Study II only included participants’ estimates of ingested doses of psilocybin. This gives rise to the possibility that what constitutes a low or high dose could differ across participants. It is also possible that those who had a strong experience may be biased to rate their dose as relatively higher because they had a strong experience, not because they actually received a higher dose. Study I only included a few participants and the results of the analyses should therefore be interpreted with caution. Overall, the findings should therefore be regarded as preliminary and should be replicated in controlled studies.

Conclusion

The findings presented in this paper are in line with previous research showing good psychometric properties of the 5D-ASC and indicate that the Danish translation of the 5D-ASC captures relevant aspects of the ASC occasioned by psilocybin in a psychometrically sound manner, both when scored with five dimensions and 11 subscales. We recommend based on our present findings that future research into classical psychedelics should investigate which of the two ways of scoring the 5D-ASC is most predictable of treatment outcome in clinical trials. The inclusion of a laboratory sample that had received a known dosage of psilocybin and completed the 5D-ASC on the day of the experience adds to the validity of our naturalistic sample and can also add to the validity of any future naturalistic validations of the 5D-ASC. We recommend future research with Danish-speaking participants to use the presented Danish translation of the 5D-ASC to collect information about psychedelic experiences.

Supplemental Material

sj-docx-1-jop-10.1177_02698811241269669 – Supplemental material for Altered states of consciousness in Danish healthy volunteers and recreational users of psilocybin and the possible impact of setting and intention: Danish validation of the five-dimensional altered states of consciousness questionnaire

Supplemental material, sj-docx-1-jop-10.1177_02698811241269669 for Altered states of consciousness in Danish healthy volunteers and recreational users of psilocybin and the possible impact of setting and intention: Danish validation of the five-dimensional altered states of consciousness questionnaire by Oliver Rumle Hovmand, Martin Korsbak Madsen, Patrick MacDonald Fisher and Dea Siggaard Stenbæk in Journal of Psychopharmacology

Footnotes

Authors contribution

ORH prepared the questionnaire and organized data collection and participant recruitment from the recreative sample. DSS and MKM collected the data from the healthy volunteers. DSS and PMF organized the translation of the psychometric instruments. ORH processed the data and carried out statistical analyses. ORH wrote the majority of the manuscript. DSS contributed with significant guidance throughout the entire project. All authors read and approved the final manuscript.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Oliver Rumle Hovmand

Patrick MacDonald Fisher

Dea Siggaard Stenbæk

Supplemental material

Supplemental material for this article is available online.

References

Becker

Klaiber

Holze

, et al. (2023) Ketanserin reverses the acute response to LSD in a randomized, double-blind, placebo-controlled, crossover study in healthy participants. Int J Neuropsychopharmacol 26: 97–106.

Bland

(1997) Statistics notes: Cronbach’s alpha. BMJ 314: 572.

Bodmer

(1989) Konstruktion des Fragebogens OAV zut quantitativen Erfassung auβergewöhnlicher Bewuβtseinszustände (ABZ). Zurich, Switzerland: University of Zurich.

Bogenschutz

Forcehimes

Pommy

, et al. (2015) Psilocybin-assisted treatment for alcohol dependence: A proof-of-concept study. J Psychopharmacol 29: 289–299.

Bogenschutz

Ross

Bhatt

, et al. (2022) Percentage of heavy drinking days following psilocybin-assisted psychotherapy versus placebo in the treatment of adult patients with alcohol use disorder: A randomized clinical trial. JAMA Psychiatry 79: 953–962.

Bouso

González

Fondevila

, et al. (2012) Personality, psychopathology, life attitudes and neuropsychological performance among ritual users of Ayahuasca: A longitudinal study. PLoS One 7: e42421.

Carhart-Harris

Bolstridge

Rucker

, et al. (2016) Psilocybin with psychological support for treatment-resistant depression: An open-label feasibility study. Lancet Psychiatry 3: 619–627.

Carhart-Harris

Giribaldi

Watts

, et al. (2021) Trial of psilocybin versus escitalopram for depression. N Engl J Med 384: 1402–1411.

Cole

(1987) Utility of confirmatory factor analysis in test validation research. J Consult Clin Psychol 55: 584–594.

10.

Davis

Barrett

May

, et al. (2021) Effects of psilocybin-assisted therapy on major depressive disorder: A randomized clinical trial. JAMA Psychiatry 78: 481–489.

11.

Dittrich

(1975) Zusammenstellung eines Fragebogens (APZ) zur Erfassung abnormer psychischer Zustände [Construction of a questionnaire (APZ) for assessing abnormal mental states]. Z Klin Psychol Psychiatr Psychother 23: 12–20.

12.

Dittrich

(1985a) Ätiologie-unabhängige Strukturen veränderter Wachbewusstseinszustände. Ergebnisse empirischer Untersuchungen über Halluzinogene I. und II. Ordnung, sensorische Deprivation, Hypnagoge Zustände, Hypnotische Verfahren Sowie Reizüberflutung [Etiology-Independent Structures of Altered States of Consciousness. Results of Empirical Studies on Hallucinogens of the First and Second Order, Sensory Deprivation, Hypnagogic States, Hypnotic Procedures, and Sensory Overload]. Stuttgart, Germany: Enke.

13.

Dittrich

(1985b) International study on altered states of consciousness (ISASC): Summary of the results. Ger J Psychol 9: 319–339.

14.

Dittrich

(1998) The standardized psychometric assessment of altered states of consciousness (ASCs) in humans. Pharmacopsychiatry 31: 80–84.

15.

Dittrich

Lamparter

Maurer

(2006) 5D-ABZ: Fragebogen zur Erfassung Aussergewöhnlicher Bewusstseinszustände. Eine kurze Einführung [5D-ASC: Questionnaire for the Assessment of Altered States of Consciousness. A Short Introduction]. Zürich: PSIN PLUS Publications.

16.

Dittrich

(2010) 5D-ASC: Questionnaire for the assessment of altered states of consciousness. A short introduction. Zurich, Switzerland: PSIN PLUS.

17.

Garcia-Romeu

Griffiths

Johnson

(2014) Psilocybin-occasioned mystical experiences in the treatment of tobacco addiction. Curr Drug Abuse Rev 7: 157–164.

18.

Goodwin

Aaronson

Alvarez

, et al. (2022) Single-dose psilocybin for a treatment-resistant episode of major depression. N Engl J Med 387: 1637–1648.

19.

Griffiths

Richards

Johnson

, et al. (2008) Mystical-type experiences occasioned by psilocybin mediate the attribution of personal meaning and spiritual significance 14 months later. J Psychopharmacol 22: 621–632.

20.

Griffiths

Johnson

Richards

, et al. (2011) Psilocybin occasioned mystical-type experiences: Immediate and persisting dose-related effects. Psychopharmacology 218: 649–665.

21.

Griffiths

Johnson

Richards

, et al. (2018) Psilocybin-occasioned mystical-type experience in combination with meditation and other spiritual practices produces enduring positive changes in psychological functioning and in trait measures of prosocial attitudes and behaviors. J Psychopharmacol 32: 49–69.

22.

Grob

Danforth

Chopra

, et al. (2011) Pilot study of psilocybin treatment for anxiety in patients with advanced-stage cancer. Arch Gen Psychiatry 68:71–78.

23.

Haijen

ECHM

Kaelen

Roseman

, et al. (2018) Predicting responses to psychedelics: A prospective study. Front Pharmacol 9: 897.

24.

Hair

(2016) A primer on partial least squares structural equation modeling (PLS-SEM). Thousand Oaks: SAGE Publications.

25.

Hartogsohn

(2016) Set and setting, psychedelics and the placebo response: An extra-pharmacological perspective on psychopharmacology. J Psychopharmacol 30: 1259–1267.

26.

Hirschfeld

Schmidt

(2021) Dose–response relationships of psilocybin-induced subjective experiences in humans. J Psychopharmacol 35: 384–397.

27.

Holze

Gasser

Müller

, et al. (2023) Lysergic acid diethylamide-assisted therapy in patients with anxiety with and without a life-threatening illness: A randomized, double-blind, placebo-controlled phase II study. Biol Psychiatry 93: 215–223.

28.

Hovmand

Poulsen

Arnfred

, et al. (2023a) Risk of bias in randomized clinical trials on psychedelic medicine: A systematic review. J Psychopharmacol 37: 649–659.

29.

Hovmand

Poulsen

Arnfred

(2023b) Assessment of the acute subjective psychedelic experience: A review of patient-reported outcome measures in clinical research on classical psychedelics. J Psychopharmacol 38: 19–32.

30.

Hovmand

Ebbesen Jensen

Søgaard Juul

, et al. (2024) Validation of the Danish Translation of the Revised Mystical Experience Questionnaire (MEQ30) and possible impact of setting, dose and intention. J Psychoactive Drugs 15: 1–10.

31.

Bentler

(2009) Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Struct Equat Model A Multidiscip J 6: 1–55.

32.

Kline

(2015) Principles and practice of structural equation modeling. New York, NY: Guilford Publications.

33.

Liechti

Dolder

Schmid

(2017) Alterations of consciousness and mystical-type experiences after acute LSD in humans. Psychopharmacology 234: 1499–1510.

34.

LimeSurvey (2012) LimeSurvey: An Open Source Survey Tool. Hamburg, Germany: LimeSurvey Project.

35.

Maclean

Leoutsakos

Johnson

, et al. (2012) Factor analysis of the mystical experience questionnaire: A study of experiences occasioned by the hallucinogen psilocybin. J Sci Study Relig 51: 721.

36.

Madsen

Fisher

Burmester

, et al. (2019) Psychedelic effects of psilocybin correlate with serotonin 2A receptor occupancy and plasma psilocin levels. Neuropsychopharmacology 44: 1328–1334.

37.

Madsen

Fisher

Stenbæk

, et al. (2020) A single psilocybin dose is associated with long-term increased mindfulness, preceded by a proportional change in neocortical 5-HT2A receptor binding. Eur Neuropsychopharmacol 33: 71–80.

38.

Madsen

Stenbæk

Arvidsson

, et al. (2021) Psilocybin-induced changes in brain network integrity and segregation correlate with plasma psilocin level and psychedelic experience. Eur Neuropsychopharmacol 50: 121–132.

39.

Moreno

Wiegand

Taitano

, et al. (2006) Safety, tolerability, and efficacy of psilocybin in 9 patients with obsessive-compulsive disorder. J Clin Psychiatry 67: 1735–1740.

40.

Nájera Catalán

(2019) Reliability, population classification and weighting in multidimensional poverty measurement: A Monte Carlo study. Soc Indic Res 142: 887–910.

41.

Nichols

(2004) Hallucinogens. Pharmacol Ther 101: 131–181.

42.

Nichols

(2016) Psychedelics. Pharmacol Rev 68: 264–355.

43.

Raison

Sanacora

Woolley

, et al. (2023) Single-dose psilocybin treatment for major depressive disorder: A randomized clinical trial. JAMA 330: 843–853.

44.

Revelle

Zinbarg

(2009) Coefficients alpha, beta, omega and the glb: Comments on Sijtsma. Psychometrika 74: 145–154.

45.

Rewelle

(2007) Psych: Procedures for psychological, psychometric, and personality research. Package for R Statistical Software. https://CRAN.R-project.org/package=psych

46.

Roseman

Nutt

Carhart-Harris

(2018) Quality of acute psychedelic experience predicts therapeutic efficacy of psilocybin for treatment-resistant depression. Front Pharmacol 8: 974.

47.

Ross

Bossis

Guss

, et al. (2016) Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: A randomized controlled trial. J Psychopharmacol 30: 1165–1180.

48.

Rosseel

(2012) Lavaan: An R package for structural equation modeling. J Statist Softw 48: 1–36.

49.

RStudio (2019) RStudio: Integrated Development for R. Boston, MA: RStudio, Inc.

50.

Schmid

(2018) Long-lasting subjective effects of LSD in normal subjects. Psychopharmacology 235: 535–545.

51.

Søndergaard

Madsen

Ozenne

, et al. (2023) Lasting increases in trait mindfulness after psilocybin correlate positively with the mystical-type experience in healthy individuals. Front Psychol 13: 948729.

52.

Studerus

Gamma

Vollenweider

(2010) Psychometric evaluation of the altered states of consciousness rating scale (OAV). PLoS One 5: e12412.

53.

Valle

Maqueda

Rabella

, et al. (2016) Inhibition of alpha oscillations through serotonin-2A receptor activation underlies the visual effects of ayahuasca in humans. Eur Neuropsychopharmacol 26: 1161–1175.

54.

von Rotz

Schindowski

Jungwirth

, et al. (2023) Single-dose psilocybin-assisted therapy in major depressive disorder: A placebo-controlled, double-blind, randomised clinical trial. EClinicalMedicine 56: 101809.

55.

Wheaton

Muthén

Alwin

, et al. (1977) Assessing reliability and stability in panel models. Sociol Methodol 8: 84–136.

Supplementary Material

Please find the following supplemental material available below.

For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.

For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.

0.00 MB

0.01 MB