Psychosis-like, psychedelic and alcohol-like states induced by nitrous oxide in healthy volunteers Not Applicable
Conditions
Interventions
Medical air (placebo, BOC, UK) or Entonox (BOC, UK), which is a premixed gas containing 50% N20 and 50% oxygen.
For hypothesis 1 (psychosis-like and psychedelic effects) and hypothesis
medical air). The within-subjects factor (Time) has three levels (pre-inhalation, on-gas, post-inhalation). Fifty participants will be equally and randomly assigned to Group using a random number gene
N2O: n=25) without reference to scores on trait measures and will form the sample used to address hypothesis 1 (psychosis-like and psychedelic effects) and hypothesis 2 (alcohol-like effects). An addi
N2O: n=15). ‘Non-bipolar’ participants (the other level of the Phenotype factor) will be the n=30 (medical air: n=15
N2O: n=15) lowest scoring participants from the initial n=50, non-purposively recruited sample.
Sponsors
University College London
Eligibility
Sex/Gender
All
Inclusion criteria
Inclusion criteria: 1. Age: 18-40 2. Fluency in written and spoken English 3. Consumes alcohol as social drinker 4. For hypothesis related to moderation of subjective effects by bipolar phenotype, participants will be high scores (>=7) on the Mood Disorder Questionnaire
Exclusion criteria
Exclusion criteria: 1. Are pregnant or are likely to become pregnant during the study or breastfeeding. 2. Suffer from any major physical health disorder 3. Are currently seeking/receiving treatment for any psychiatric condition 4. Have asthma or any breathing difficulty (including sleep apnoea) 5. Have a cardiovascular condition or a fitted pacemaker 6. Have any liver or kidney disorder 7. Have had a ‘collapsed lung’ 8. Have difficulties metabolising vitamin B12 9. Have anaemia 10. Have history of stomach ulcers 11. Have high or low blood pressure 12. Have a current ear or sinus infection or a bad cold 13. Have epilepsy 14. Have ever had neurosurgery 15. Are diabetic 16. Have had any recent dental work or dental infection/inflammation 17. Have had any adverse reaction to nitrous oxide in the past 18. Use recreational drugs more than once a week 19. Are unable/unwilling to abstain from drugs and alcohol for 24 hours prior to the study
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Psychosis-like/Psychedelic effects of N2O 1. Psychosis-like (‘psychotomimetic’) states will be assessed using the Psychotomimetic States Inventory (PSI) total and subscale scores (particularly ‘Delusory Thinking’, ‘Perceptual Distortions’, ‘Cognitive Disorganization’, and ‘Paranoia’). The PSI will be administered pre-, during and 15 min after gas inhalation. 2. Altered states of consciousness will be assessed using the 42-item version of the Questionnaire for the Assessment of Altered States of Consciousness (Studerus et al., 2010) administered only on-gas. Alcohol-like effects of N2O 1. Similarity of current subjective state to (previously experienced) subjective effects of alcohol, cannabis and cocaine, will be assessed using the Sensation Scale (0-100 visual analogue scale; Krystal et al, 1998) assessed pre-, on-gas and post-inhalation 2. Equivalence in (N2O-induced) intoxication to a specific amount of alcohol will be assessed using the Number of Drinks Scale (NDS; Krystal et al, 1998) at pre-, on-gas and post-inhalation time-points. 3. Subjective stimulant and sedative effects of nitrous oxide will be assessed using the Brief Biphasic Alcohol Effects Scale (B-BAES; Rueger et al, 2009) assessed pre-, on-gas and post-inhalation. 4. General subjective drug effects will be assessed using the ‘feel high’ and ‘feel effect’ items of the Drug Effects Questionnaire (DEQ; Morean et al, 2013), per Yip et al’s (2012) study on alcohol and bipolar phenotype. Secondarily, hedonic and anti-hedonic effects of gas inhalation will be assessed using the ‘liking’ and ‘disliking’ items, and motivational effects, using the ‘wanting more’ item of the DEQ. The former four items will be assessed pre-, on-gas and post-inhalation (+ 15 min), and ‘wanting more’, only on-gas and post-inhalation. | — |
Secondary
| Measure | Time frame |
|---|---|
| Additional measures below are potentially important covariates/moderators (especially the MDQ scores) or cofounding factors (rather than ‘outcomes’ per se) that we wish to assess for similarity between groups at baseline or test in exploratory analyses: 1. State dissociation will be assessed using the Clinician Administered Dissociative Symptoms Scale (self-report items; Bremner et al 1998), pre-, on-gas and post-inhalation. 2. ‘Trait’ dissociation symptoms will be assessed with the Brief Dissociative Experiences Scale (DES-B; modified for DSM-V by Dalenberg and Carlson, 2010) – pre-inhalation only. 3. Impulsivity will be assessed with the Barratt Impulsivity Scale 11-Brief (Steinberg et al, 2013) – pre-inhalation only. 4. Historical and recent subjective response to alcohol will be assessed using the Subjective Response to Alcohol measure (Schuckit 1984) – pre-inhalation only. 5. Bipolar phenotype will be assessed using the Mood disorders Questionnaire (MDQ; Hirschfeld et al, 2000) – pre-inhalation only. 6. Schizotypy will be assessed with the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE) short form; unusual experiences subscale (Mason et al, 2005) – pre-inhalation only. 7. Problematic alcohol use will be assessed using the Alcohol Use Disorders Identification Test (AUDIT) – pre-inhalation only. 8. Recent alcohol use (previous week) will be assessed using the Timeline Follow-back diary method - pre-inhalation only. 9. Family history of alcohol problems will be assessed using a Family History of Alcohol Problems family tree method - pre-inhalation only. 10. General mood will be assessed using the Depression, Anxiety and Stress Scale (DASS-21; Lovibond & Lovibond, 1995) - pre-inhalation only. | — |
Countries
United Kingdom
Outcome results
None listed