Blunted highs: Pharmacodynamic and behavioral models of cannabis tolerance

Evaluating possible 'next day' impairment in insomnia patients administered an oral medicinal cannabis product by night: a pilot randomized controlled trial

Cannabis and its major constituents, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), are being widely used to treat sleep disturbances. However, THC can cause acute cognitive and psychomotor impairment and there are concerns that driving and workplace safety might be compromised the day after evening use. Here, we examined possible 'next day' impairment following evening administration of a typical medicinal cannabis oil in adults with insomnia disorder, compared to matched placebo. This paper describes the secondary outcomes of a larger study investigating the effects of THC/CBD on insomnia disorder. Twenty adults [16 female; mean (SD) age, 46.1 (8.6) y] with physician-diagnosed insomnia who infrequently use cannabis completed two 24 h in-laboratory visits involving acute oral administration of combined 10 mg THC and 200 mg CBD ('THC/CBD') or placebo in a randomised, double-blind, crossover trial design. Outcome measures included 'next day' (≥9 h post-treatment) performance on cognitive and psychomotor function tasks, simulated driving performance, subjective drug effects, and mood. We found no differences in 'next day' performance on 27 out of 28 tests of cognitive and psychomotor function and simulated driving performance relative to placebo. THC/CBD produced a small decrease (-1.4%, p=.016, d=-0.6) in accuracy on the Stroop-Colour Task (easy/congruent) but not the Stroop-Word Task (hard/incongruent). THC/CBD also produced a small increase (+8.6, p=.042, d=0.3) in self-ratings of Sedated at 10 h post-treatment, but with no accompanying changes in subjective ratings of Alert or Sleepy (p's>0.05). In conclusion, we found a lack of notable 'next day' impairment to cognitive and psychomotor function and simulated driving performance following evening use of 10 mg oral THC, in combination with 200 mg CBD, in an insomnia population who infrequently use cannabis.

The relationship between clinical impairment and blood drug concentration: Comparison between the most prevalent traffic relevant drug groups

AIM

The aim of the present study was to investigate the relationship between blood concentrations of four different drug classes; ethanol, benzodiazepines, amphetamines and tetrahydrocannabinol (THC) and driver impairment as assessed by a clinical test of impairment (CTI).

METHODS

Data was retrieved from a national database on CTI assessments and accompanying blood drug concentrations from apprehended drivers. All drug concentrations in blood were quantified using Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS), and compared to the results of the CTI which were categorized as either "not impaired", "mildly impaired", "moderately impaired", or "considerably impaired".

RESULTS

A total number of 15 514 individual mono drug-cases collected over 9 years was included. 89 % were men and the median age was 34 years. In addition, 3 684 individual cases with similar age and gender distribution where no drugs were detected, were included as a reference group. For ethanol and benzodiazepines the percentage of clinically impaired cases increased markedly from lower to higher concentration windows, from 60 % to 97 % for ethanol and from 38 % to 76 % for benzodiazepines. The corresponding increase for amphetamines and THC was modest, from 43 % to 58 % for amphetamines and from 41 % to 55 % for THC. The correlation between drug concentration and degree of impairment was high for ethanol (Spearman´s rho=0.548, p<0.001) and relatively high for benzodiazepines (Spearman´s rho=0.377, p<0.001), but low for amphetamines (Spearman´s rho=0.078, p<0.001) and THC (Spearman´s rho=0.100, p<0.001).

CONCLUSION

The percentage of impaired drivers increased with increasing blood drug concentration for all four drug classes, most pronounced for ethanol and benzodiazepines and much less for amphetamines and THC. The median blood drug concentration increased with increasing magnitude of impairment for ethanol and benzodiazepines, while this was much less pronounced for amphetamines and THC. The ranges of drug concentrations, however, were wide for all four drug classes in all impairment categories as assessed by individual clinical examination.

Intoxication due to Δ9-tetrahydrocannabinol is characterized by disrupted prefrontal cortex activity

Neural states of impairment from intoxicating substances, including cannabis, are poorly understood. Cannabinoid 1 receptors, the main target of Δ9-tetrahydrocannabinol (THC), the primary intoxicating cannabinoid in cannabis, are densely localized within prefrontal cortex; therefore, prefrontal brain regions are key locations to examine brain changes that characterize acute intoxication. We conducted a double-blind, randomized, cross-over study in adults, aged 18-55 years, who use cannabis regularly, to determine the effects of acute intoxication on prefrontal cortex resting-state measures, assessed with portable functional near-infrared spectroscopy. Participants received oral THC (10-80 mg, individually dosed to overcome tolerance and achieve acute intoxication) and identical placebo, randomized for order; 185 adults were randomized and 128 completed both study days and had usable data. THC was associated with expected increases in subjective intoxication ratings (ES = 35.30, p < 0.001) and heart rate (ES = 11.15, p = 0.001). THC was associated with decreased correlations and anticorrelations in static resting-state functional connectivity within the prefrontal cortex relative to placebo, with weakest correlations and anticorrelations among those who reported greater severity of intoxication (RSFC between medial PFC-ventromedial PFC and DEQ scores, r = 0.32, p < 0.001; RSFC between bilateral mPFC and DEQ scores, r = -0.28, p = 0.001). Relative to placebo, THC was associated with increased variability (or reduced stability) in dynamic resting-state functional connectivity of the prefrontal cortex at p = 0.001, consistent across a range of window sizes. Finally, using frequency power spectrum analyses, we observed that relative to placebo, THC was associated with widespread reduced spectral power within the prefrontal cortex across the 0.073-0.1 Hz frequency range at p < 0.039. These neural features suggest a disruptive influence of THC on the neural dynamics of the prefrontal cortex and may underlie cognitive impairing effects of THC that are detectable with portable imaging. This study is registered in Clinicaltrials.gov (NCT03655717).

Clinical outcome analysis of patients with multiple sclerosis - Analysis from the UK Medical Cannabis Registry

INTRODUCTION

Whilst disease-modifying therapies are the cornerstone for treatment of multiple sclerosis (MS), there is a need to develop novel therapeutics for the symptomatic sequalae of the disease. Cannabis-based medicinal products (CBMPs) have been suggested as a potential therapy for the associated pain, spasticity, and mental health disorders. However, there is a paucity of clinical evidence on CBMPs in MS. The aim of this study is to assess changes in MS-specific and general health-related quality of life (HRQoL) outcomes alongside adverse event incidence in patients prescribed CBMPs for MS from the UK Medical Cannabis Registry (UKMCR).

METHOD

Patients prescribed CBMPs for MS symptoms for longer than one month were identified from the UKMCR. The primary outcomes were changes from baseline in MS Quality of Life-54 (MSQoL-54), Generalised Anxiety Disorder-7 (GAD-7), Single-Item Sleep Quality Scale (SQS), and EQ-5D-5L scales at one month, three months and six months. p < 0.050 was defined as statistically significant.

RESULTS

141 patients met the inclusion criteria for the study. There was an improvement in the following subscales of the MSQoL-54 at 6 months: change in health scale, cognitive function, mental health composition, physical health, role limitations due to physical limitation and due to emotional problems, as well as social and sexual function (p < 0.050). There were also improvements in the EQ-5D-5L index value, GAD-7 and SQS (p < 0.050). 146 (103.55 %) adverse events were reported in total. Most were considered mild (n = 47; 33.33 %) and moderate (n = 72; 51.06 %).

CONCLUSIONS

This preliminary analysis demonstrates a possible association with improved general health-related quality of life in those prescribed CBMPs for MS. Moreover, the results suggest that CBMPs are well-tolerated in the first 6 months of treatment. However, this must be interpreted with caution considering the limitations of the observational study design.

Acute Cannabis Administration Transiently Reduces Mitochondrial DNA in Young Adults: Findings from a Secondary Analysis of a Double-Blind, Placebo-Controlled, Randomized Clinical Trial

Background: Cannabis is one of the world's most commonly used substances; however, many questions remain unanswered as to how cannabis impacts the body. Recently, there has been a resurgence of research into the effects of plant-derived cannabinoids on mitochondrial health. In particular, a number of studies implicate mitochondrial-Δ9-tetrahydrocannabinol (Δ9-THC) interactions with altered memory, metabolism, and catalepsy in mice. Although the research in this field is expanding rapidly, there is little known about the effects of cannabis on mitochondria health in human subjects either in acute or chronic term use. Methods: Blood samples were obtained from a double-blind, placebo-controlled, parallel-group randomized clinical trial in which adults who regularly use cannabis (1-4 days/week) aged 19-25 years were randomized 2:1 to receive either an active (12.5% Δ9-THC) cigarette or placebo (<0.01% Δ9-THC) cigarette containing 750 mg of cannabis before driving simulator testing. DNA was extracted from whole blood using commercial spin columns, followed by measurement of mt-ND1, mt-ND4, and β2M using quantitative polymerase chain reaction. One-way repeated measures analysis of variance (ANOVA) followed by Dunnett's multiple comparisons test was used to observe changes in mitochondrial DNA (mtDNA) copy number over time. A two-tailed Pearsons R test was used to assess correlations between mtDNA copy number and cannabinoid levels (Δ9-THC and metabolites) in blood. Results: We found that exposure to active cannabis containing Δ9-THC, as opposed to placebo, was associated with an acute reduction in mitochondrial DNA copy number in whole blood at 15 min and 1 h after smoking. The observed decrease in mtDNA copy number negatively correlated with blood concentrations of 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC) and 11-Nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH), the two primary metabolites of Δ9-THC, but not Δ9-THC itself. Further, the negative correlation between 11-OH THC and THC-COOH concentrations and mtDNA copy number was found in only a subgroup of participants who use cannabis infrequently, suggesting a tolerance effect. Conclusions: These results illuminate mitochondrial alterations attributed to Δ9-THC consumption, which may be mediated by metabolites. These results appear to suggest stronger effects in individuals who consume cannabis less frequently, suggesting some form of tolerance to the effects of Δ9-THC and its metabolites on mtDNA content in whole blood. Keywords: Mitochondria; mtDNA; cannabis; THC; THC metabolites; blood; THC-COOH; 11-OH-THC.

Enhancing the Preanesthesia Evaluation: Consensus Development of the Cannabis Use and Behaviors Assessment Tool (CUBAT)

PURPOSE

This project aimed to develop an evidence-based preanesthesia cannabis use assessment tool to acquire complete and accurate patient history and develop a best-informed, individualized anesthesia and analgesia care plan.

DESIGN

Modified Delphi.

METHODS

Using an evidence synthesis and multistage, modified Delphi process, eight experts from across the United States developed a consensus-based tool to aid in developing a best-informed, individualized plan for anesthesia and analgesia care.

FINDINGS

Two survey rounds integrated informed evidence-based tool revisions. The final tool included instructions for use, a glossary of terms, and seven key assessment items aimed at gathering the most influential information regarding cannabis use.

CONCLUSIONS

The Cannabis Use and Behaviors Assessment Tool is a first-of-its-kind tool providing an essential framework for preanesthesia cannabis use assessment.

Tolerability of High-Dose Oral Δ9-THC: Implications for Human Laboratory Study Design

Background: Δ9-tetrahydrocannabinol (THC), the primary intoxicating compound in cannabis, has been tested extensively in controlled administration human studies. Some studies require a high THC dose that may induce adverse events (AEs), such as those testing novel treatments for cannabinoid overdose. Although there are ethical concerns related to administering high THC doses, there is no systematic analysis on studies utilizing these doses. In this review, we examine studies that administered oral THC doses ≥30 mg ("high-dose THC"), focusing on reported tolerability, subjective effects, and pharmacokinetics (PK), with the objective to inform the design of future studies. Methods: A comprehensive PubMed search was performed to identify studies meeting pre-specified criteria. Results: Our search identified 27 publications from 17 high-dose oral THC laboratory studies, with single doses up to 90 mg and multiple doses up to 210 mg per day. The maximum plasma THC concentration (Cmax) appeared to increase in a dose-proportional manner over this dose range. All high-dose THC studies enrolled participants with previous cannabis experience, although current use ranged from nonusers to regular cannabis users. High-dose THC was generally well tolerated with transient mild to moderate AE, including nausea and vomiting, anxiety, paranoia, and sedation. There were occasional participant withdrawals due to AEs, but there were no serious AE. Participants with frequent cannabis use tolerated high-dose THC best. Conclusion: Although based on limited data, THC was generally adequately tolerated with single oral doses of at least 50 mg in a controlled laboratory setting in healthy participants with past cannabis experience.

A semi-naturalistic open-label study examining the effect of prescribed medical cannabis use on simulated driving performance

BACKGROUND

Despite increasing medical cannabis use, research has yet to establish whether and to what extent products containing delta-9-tetrahydrocannabinol (THC) impact driving performance among patients. Stable doses of prescribed cannabinoid products during long-term treatment may alleviate clinical symptoms affecting cognitive and psychomotor performance.

AIM

To examine the effects of open-label prescribed medical cannabis use on simulated driving performance among patients.

METHODS

In a semi-naturalistic laboratory study, 40 adults (55% male) aged between 23 and 80 years, consumed their own prescribed medical cannabis product. Driving performance outcomes including standard deviation of lateral position (SDLP), the standard deviation of speed (SDS), mean speed and steering variability were evaluated using the Forum8 driving simulator at baseline (pre-dosing), 2.5 h and 5 -h (post-dosing). Perceived driving effort (PDE) was self-reported after each drive. Oral fluid and whole blood samples were collected at multiple timepoints and analysed for THC via liquid chromatography-mass spectrometry.

RESULTS

A significant main effect of time was observed for mean speed (p = 0.014) and PDE (p = 0.020), with patients displaying modest stabilisation of vehicle control, increased adherence to speed limits and reductions in PDE post-dosing, relative to baseline. SDLP (p = 0.015) and PDE (p = 0.043) were elevated for those who consumed oil relative to flower-based products. Detectable THC concentrations were observed in oral fluid at 6-h post-dosing (range = 0-24 ng/mL).

CONCLUSIONS

This semi-naturalistic study suggests that the consumption of medical cannabis containing THC (1.13-39.18 mg/dose) has a negligible impact on driving performance when used as prescribed.

A cohort study comparing the effects of medical cannabis for anxiety patients with and without comorbid sleep disturbance

BACKGROUND

Research on cannabis-based medicinal products (CBMPs) in anxiety remains inconclusive due to a paucity of high-quality evidence. Studies indicate a bidirectional relationship between generalized anxiety disorder (GAD) and sleep disruption, but it is unclear how this affects CBMP treatment outcomes. This study aims to compare the patient-reported outcome measures (PROMs) of patients prescribed CBMPs for GAD, with and without impaired sleep.

METHODS

Changes in PROMs were recorded from baseline to 1, 3, 6, and 12 months between those with impaired or unimpaired sleep. Multivariate logistic regression was applied to compare factors associated with a clinically significant improvement in GAD-7 at 12 months. Secondary outcomes included adverse event incidence and frequency.

RESULTS

Of the 302 patients that fit the inclusion criteria, mean GAD-7, single-item sleep quality, and EQ-5D-5L index values improved at all time points (p < 0.001). A relationship between sleep impairment and clinically significant changes in GAD-7 at 1 and 3 months was identified (p ≤ 0.01). On multivariate regression, only baseline GAD severity was associated with an increased likelihood of observing a clinically significant improvement in anxiety (p < 0.001). Seven hundred and seven (234%) adverse events were reported by 55 (18.21%) participants.

CONCLUSIONS

This study observed an association between CBMP treatment and improvements in anxiety in patients with GAD. While patients with comorbid sleep disruption had greater improvements in anxiety, the differences were not maintained in a multivariate analysis. Baseline anxiety severity may be a predictor for CBMP treatment outcomes.

Effects of acute cannabis inhalation on reaction time, decision-making, and memory using a tablet-based application

BACKGROUND

Acute cannabis use has been demonstrated to slow reaction time and affect decision-making and short-term memory. These effects may have utility in identifying impairment associated with recent use. However, these effects have not been widely investigated among individuals with a pattern of daily use, who may have acquired tolerance. The purpose of this study was to examine the impact of tolerance to cannabis on the acute effects as measured by reaction time, decision-making (gap acceptance), and short-term memory.

METHODS

Participants (ages 25-45) completed a tablet-based (iPad) test battery before and approximately 60 min after smoking cannabis flower. The change in performance from before to after cannabis use was compared across three groups of cannabis users: (1) occasional use (n = 23); (2) daily use (n = 31); or (3) no current use (n = 32). Participants in the occasional and daily use group self-administered ad libitum, by smoking or vaping, self-supplied cannabis flower with a high concentration of total THC (15-30%).

RESULTS

The occasional use group exhibited decrements in reaction time (slowed) and short-term memory (replicated fewer shapes) from before to after cannabis use, as compared to the no-use group. In the gap acceptance task, daily use participants took more time to complete the task post-smoking cannabis as compared to those with no use or occasional use; however, the level of accuracy did not significantly change.

CONCLUSIONS

The findings are consistent with acquired tolerance to certain acute psychomotor effects with daily cannabis use. The finding from the gap acceptance task which showed a decline in speed but not accuracy may indicate a prioritization of accuracy over response time. Cognitive and psychomotor assessments may have utility for identifying impairment associated with recent cannabis use.

Impact of Δ9-Tetrahydrocannabinol and oxycodone co-administration on measures of antinociception, dependence, circadian activity, and reward in mice

Oxycodone is commonly prescribed for moderate to severe pain disorders. While efficacious, long-term use can result in tolerance, physical dependence, and the development of opioid use disorder. Cannabis and its derivatives such as Δ9-Tetrahydrocannabinol (Δ9-THC) have been reported to enhance oxycodone analgesia in animal models and in humans. However, it remains unclear if Δ9-THC may facilitate unwanted aspects of oxycodone intake, such as tolerance, dependence, and reward at analgesic doses. This study sought to evaluate the impact of co-administration of Δ9-THC and oxycodone across behavioral measures related to antinociception, dependence, circadian activity, and reward in both male and female mice. Oxycodone and Δ9-THC produced dose-dependent antinociceptive effects in the hotplate assay that were similar between sexes. Repeated treatment (twice daily for 5 days) resulted in antinociceptive tolerance. Combination treatment of oxycodone and Δ9-THC produced a greater antinociceptive effect than either administered alone, and delayed the development of antinociceptive tolerance. Repeated treatment with oxycodone produced physical dependence and alterations in circadian activity, neither of which were exacerbated by co-treatment with Δ9-THC. Combination treatment of oxycodone and Δ9-THC produced CPP when co-administered at doses that did not produce preference when administered alone. These data indicate that Δ9-THC may facilitate oxycodone-induced antinociception without augmenting certain unwanted features of opioid intake (e.g. dependence, circadian rhythm alterations). However, our findings also indicate that Δ9-THC may facilitate rewarding properties of oxycodone at therapeutically relevant doses which warrant consideration when evaluating this combination for its potential therapeutic utility.

Driving under the influence of cannabis: A 5-year retrospective Italian study

INTRODUCTION

Cannabis consumption is associated with driving impairment and increased crash risk, endangering road safety. Toxicological analyses play a fundamental role in detecting a recent consumption of psychoactive substances. The aim of this study was to examine the concentration of cannabinoids in blood samples of driving-under-the-influence (DUI) offenders in order to investigate whether delayed sample collection affects the toxicological assessment of the offenders.

MATERIALS AND METHODS

An observational retrospective study was performed using anonymized toxicological data referring to cannabis-related DUI offenders involved in road traffic accidents (RTA) or apprehended by the police from 1 January 2017-31 December 2021 archived at Legal Medicine and Toxicology Department of the University Hospital of Padova, Italy.

RESULTS

In a total sample of 318 drivers, 143 blood samples tested positive for tetrahydrocannabinol (THC) and metabolites 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC) and 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), and 173 blood samples were positive for THC-COOH with THC negative. In the first group, the mean concentrations of THC and THC-COOH were 4.05 ng/mL and 28.29 ng/mL, respectively. In THC-negative cases, the mean THC-COOH concentration was 7.3 ng/mL. The time elapsed between the event and sample collection varied from 15 min to 7 h (mean 2 h 29 min). The average estimated time elapsed after consumption of cannabinoids was 3 h 7 min (Model I) and 2 h 36 min (Model II).

CONCLUSIONS

The present research discussed the main difficulties in the toxicological evaluation of drivers under the influence of Cannabis. Issues related to the time between RTA and sample collection, the laws and legal limits in force in various Countries were presented.

Dose-dependent Relationships of Same-day and Typical Substance Use to Sleep Duration in College Cannabis and Alcohol Users: A Multilevel Modeling Approach Using Daily Diary Data

This study characterized how quantities of cannabis and alcohol use affect sleep. Single-day and typical cannabis and alcohol use patterns were considered to assess acute-chronic use interactions. Linear and non-linear associations assessed dose-dependence. College students (n=337; 52% female) provided 11,417 days of data, with up to five time points per day. Daily self-reported sleep duration, cannabis use quantity, and alcohol use quantity were subjected to linear mixed modeling to capture linear and curvilinear associations between single-day and typical use on same-night and typical sleep. Sleep duration (difference between bedtime and waketime) was the outcome. Quantity of cannabis used each day andtypical quantity used across all days were predictors in the cannabis models. Parallel single-day and typical alcohol variables were predictors in the alcohol models. Follow-up analyses excluded days with alcohol-cannabis co-use. Main effects of single-day and typical cannabis quantity on sleep duration were observed when all cannabis-use days were modeled. Higher than typical doses of single-day and typical cannabis were associated with longer sleep durations, but only to a point; at the highest doses, cannabis shortened sleep. A main effect of single-day alcohol quantity and two interactions (single-day use with both linear and curvilinear typical use) on sleep duration were observed when all alcohol-use days were modeled. Greater alcohol consumption on a given day led to shorter same-night sleep, but typically heavier drinkers required higher doses than typically lighter drinkers to experience these adverse effects. Follow-up models suggested alcohol co-use may contribute to the purported sleep-promoting effects of cannabis.

A Semi-Naturalistic, Open-Label Trial Examining the Effect of Prescribed Medical Cannabis on Neurocognitive Performance

BACKGROUND AND OBJECTIVES

Medical cannabis use is increasing in Australia and other jurisdictions, yet little is known about the effects of medical cannabis on cognitive function. Findings from studies of non-medical ('recreational') cannabis may not be applicable to patients using prescribed medical cannabis to manage a health condition.

METHODS

In this semi-naturalistic, open-label trial, patients with various health conditions attended a single laboratory session in which they self-administered a standard dose of prescribed medical cannabis as per instructions on the pharmacy label. We assessed cognitive performance using the Cambridge Neuropsychological Test Automated Battery (CANTAB) and Druid application (app) prior to and following (CANTAB: + 3 h; Druid: + 3 and 5.5 h) medical cannabis self-administration. We also assessed subjective drug effects prior to and following (1, 2 and 4 h) medical cannabis self-administration using a range of 0-10 cm visual analogue scales ('stoned', 'sedated', 'relaxed', 'comfortable', 'anxious' and 'confident'). Data were analyzed using linear fixed-effect models.

RESULTS

Participants (N = 40; 22 females) were prescribed a range of products including orally administered oils (n = 23) and flower for vaporization (n = 17). Participants had a mean (standard deviation [SD]) age of 41.38 (12.66) years and had been using medical cannabis for a mean (SD) of 10.18 (8.73) months. Chronic non-cancer pain was the most common indication for medical cannabis use (n = 20), followed by sleep disorder (n = 18) and anxiety (n = 11). The mean (SD) delta-9-tetrahydrocannabinol (THC)/cannabidiol (CBD) dose administered by participants was 9.61 (8.52) mg/9.15 (10.11) mg among those using an oil, and 37.00 (24.53) mg/0.38 (1.58) mg among those who vaporized flower, respectively. Participants' performance improved over time on the CANTAB Multitasking Test and Rapid Visual Information Processing test (both p-values <0.001). All other changes in cognitive performance measures over time were non-significant (p > 0.05). Vaporization of flower was associated with significantly stronger subjective feelings of 'stoned' and 'sedated' relative to oils (both p < 0.001).

CONCLUSIONS

These findings suggest that prescribed medical cannabis may have minimal acute impact on cognitive function among patients with chronic health conditions, although larger and controlled trials are needed.

Altered State of Consciousness and Mental Imagery as a Function of N, N-dimethyltryptamine Concentration in Ritualistic Ayahuasca Users

Consumption of the psychedelic brew ayahuasca is a central ritualistic aspect of the Santo Daime religion. The current observational, baseline controlled study was designed to assess whether members (n = 24) of the Santo Daime church would show enhanced capacity for mental imagery during an ayahuasca experience. In addition, this study assessed whether the effects of ayahuasca on consciousness and mental imagery were related to peak serum concentration of N, N-dimethyltryptamine (DMT), the main psychoactive component. Measures of altered states of consciousness (5-Dimensional Altered States of Consciousness Questionnaire) and ego dissolution (Ego Dissolution Inventory [EDI]) as well as measures of mental imagery (visual perspective shifting, vividness of visual imagery, cognitive flexibility, associative thinking) were taken on two subsequent days on which members of Santo Daime were sober or drank a self-selected volume of ayahuasca. Measures of altered states of consciousness revealed that feelings of oceanic boundlessness, visual restructuralization, and EDI increased most prominently after drinking and shared a positive correlation with peak DMT concentration. Measures of mental imagery did not noticeably differ between the baseline and ayahuasca condition, although subjective ratings of cognitive flexibility were lower under ayahuasca. Two measures related to mental imagery, that is, perspective shifts and cognitive flexibility, were significantly correlated to peak DMT concentrations. Peak concentrations of DMT and other alkaloids did not correlate with ayahuasca dose. These findings confirm previous notions that the primary phenomenological characteristics of ayahuasca are driven by DMT. Compensatory or neuroadaptive effects associated with long-term ayahuasca intake may have mitigated the acute impact of ayahuasca in Santo Daime members on mental imagery.

Cannabis use breaks in young adults: The highs and lows of tolerance breaks

BACKGROUND/PURPOSE

Cannabis tolerance breaks, or T-breaks, are believed to benefit persons who use cannabis (PUCs) by decreasing tolerance levels to cannabis. However, no prior research, to our knowledge, has compared the effects of T-breaks and other use breaks on cannabis use patterns and outcomes. The current study examined whether the occurrence of cannabis use breaks (tolerance and other use breaks), or the duration of these breaks, is associated with changes in hazardous cannabis use (CUDIT-R), CUD severity, cannabis use frequency, and withdrawal symptoms over a 6-month follow-up.

METHODS

Young adults, who recreationally use cannabis, (N=170, 55.9% female, Mean age=21 yo) completed baseline and on-time 6-month assessments of hazardous cannabis use (CUDIT-R), CUD severity, cannabis use frequency, and withdrawal symptoms. The occurrence of cannabis use breaks and the duration of these breaks during the intervening period was assessed at 6 months.

RESULTS

Taking a T-break was associated with an increase in hazardous cannabis use and CUD severity at 6 months. When considering cannabis use breaks for other reasons, a longer break was associated with a significant decrease in hazardous cannabis use (CUDIT-R), CUD severity, and cannabis use frequency at 6 months.

CONCLUSION

Findings from our study suggest recreational PUCs who take a T-break may be at greater risk for problematic cannabis use. In addition, taking a longer cannabis use break for other reasons may have beneficial effects on cannabis-related outcomes. The ability to abstain from cannabis for other reasons may be protective while individuals who take T-breaks may be important targets for intervention and prevention.

Perceptions and Practices of Cannabis Use Among Emergency Department Patients

BACKGROUND

Nationally, in states where cannabis has been legalized, increases in cannabis-related hospitalizations and emergency department (ED) visits have also been observed.

OBJECTIVES

This study aims to: 1) Describe the sociodemographic characteristics of cannabis users presenting to two academic EDs in California; 2) Assess cannabis-related behaviors; 3) Assess perceptions of cannabis; 4) Identify and describe reasons for cannabis-related ED utilization.

METHODS

This is a cross-sectional study of patients visiting one of two academic EDs between February 16, 2018 and November 21, 2020. Eligible participants completed a novel questionnaire developed by the authors. Basic descriptive statistics, Pearson correlation coefficients, and logistic regression were used for statistical analysis of responses.

RESULTS

The questionnaire was completed by 2577 patients. A quarter were categorized as Current Users (n = 628, 24.4%). Current, Regular Users were evenly divided across gender, were relatively younger (18-34 years, 48.1%), and were largely non-Hispanic Caucasian. Over half of all respondents believed that the use of cannabis was less harmful than tobacco or alcohol use (n = 1537, 59.6%). One in five Current Users (n = 123, 19.8%) reported driving while using cannabis in the past month. A small proportion (n = 24, 3.9%) of Current Users reported ever visiting the ED for a cannabis-related chief complaint.

CONCLUSIONS

Overall, many ED patients are currently using cannabis; few report utilizing the ED due to cannabis-related problems. Current, Irregular Users may represent the ideal target group for ED-based educational efforts aimed at improving knowledge of safe cannabis use.

An observational study of safety and clinical outcome measures across patient groups in the United Kingdom Medical Cannabis Registry

BACKGROUND

There is a paucity of high-quality data on patient outcomes and safety after initiating treatment with cannabis-based medicinal products (CBMPs). The aim of this study was to assess the clinical outcomes and safety of CBMPs by analyzing patient-reported outcome measures and adverse events across a broad spectrum of chronic conditions.

RESEARCH DESIGN AND METHODS

This study analyzed patients enrolled in the UK Medical Cannabis Registry. Participants completed the EQ-5D-5L to assess health-related quality of life, Generalized Anxiety Disorder-7 (GAD-7) questionnaire to measure anxiety severity, and the Single-item Sleep Quality Scale (SQS) to rate sleep quality at baseline and follow-up after 1, 3, 6, and 12 months.

RESULTS

A total of 2833 participants met inclusion criteria. The EQ-5D-5L index value, GAD-7, and SQS all improved at each follow-up (p < 0.001). There was no difference in EQ-5D-5L index values between former or current illicit cannabis consumers and naïve patients (p > 0.050). Adverse events were reported by 474 (16.73%) participants.

CONCLUSIONS

This study suggests that CBMPs are associated with an improvement in health-related quality of life in UK patients with chronic diseases. Treatment was tolerated well by most participants, but adverse events were more common in female and cannabis-naïve patients.

Psychometric validity and the appropriateness of tolerance as a criterion for internet gaming disorder: A systematic review

Tolerance is a controversial but still an omnipresent criterion in measuring problematic gaming and Internet Gaming Disorder (IGD). Despite criticisms, a systematic review of its suitability has not been conducted until now. The aim of this study was to assess the evidence of psychometric validity and the appropriateness of tolerance as a criterion for IGD. A total of 61 articles were included in the review, 47 quantitative, 7 qualitative studies,plus 7 studies that introduce potential item wordings for operationalizing tolerance. Results showed that the tolerance item tends to have acceptable to high factor loadings on the single IGD factor. While tolerance sometimes did not adequately differentiate the engaged gamers from those with a probable disorder, it was endorsed at medium to high levels of IGD severity and had a good performance in the interviews. It, however, showed weak relations with distress and well-being. In qualitative studies, tolerance as currently defined by DSM-5 and measured by questionnaires (i.e., increasing amounts of time spent on gaming) was almost unequivocally rejected by gamers. The solid performance of tolerance in psychometric studies was probably due to deficiencies of the IGD construct, which also contains other disputed criteria. Tolerance lacks relevance in measuring IGD and care should be taken when using and interpreting IGD measures with this criterion.

Structure-Activity Relationship Development Efforts towards Peripherally Selective Analogs of the Cannabinoid Receptor Partial Agonist BAY 59-3074

Selective modulation of peripheral cannabinoid receptors (CBRs) has potential therapeutic applications in medical conditions, including obesity, diabetes, liver diseases, GI disorders and pain. While there have been considerable efforts to produce selective antagonists or full agonists of CBRs, there has been limited reports on the development of partial agonists. Partial agonists targeting peripheral CBRs may have desirable pharmacological profiles while not producing centrally mediated dissociative effects. Bayer reported that BAY 59-3074 is a CNS penetrant partial agonist of both CB1 and CB2 receptors with efficacy in rat models of neuropathic and inflammatory pain. In this report, we demonstrate our efforts to synthesize analogs that would favor peripheral selectivity, while maintaining partial agonism of CB1. Our efforts led to the identification of a novel compound, which is a partial agonist of the human CB1 (hCB1) receptor with vastly diminished brain exposure compared to BAY 59-3074.

Cannabinoids, Insomnia, and Other Sleep Disorders

Sleep disturbances are often cited as a primary reason for medicinal cannabis use, and there is increasing clinical interest in the therapeutic potential of cannabinoids in treating sleep disorders. Burgeoning evidence suggests a role of the endocannabinoid system in regulating the circadian sleep-wake cycle, highlighting a potential avenue for developing novel therapeutics. Despite widespread use of cannabis products as sleep aids globally, robustly designed studies verifying efficacy in sleep-disordered populations are limited. Although some study outcomes have suggested cannabinoid utility in insomnia disorder and sleep apnea, most studies to date are limited by small sample sizes, lack of rigorously controlled study designs, and high risk of bias. This critical review summarizes the current evidence for the use of cannabinoids as a treatment for sleep disorders and provides an overview of endocannabinoid modulation of sleep-wake cycles, as well as the sleep-modulating effects of plant-derived cannabinoids such as delta-9-tetrahydrocannbinol, cannabidiol, and cannabinol. The review also discusses practical considerations for clinicians regarding cannabinoid formulations, routes of administration, respiratory concerns, dosing, potential side effects, drug interactions, and effects relevant to driving, tolerance, and withdrawal. Although current interest in, and uptake of, medicinal cannabis use for sleep disorders may have surpassed the evidence base, there is a strong rationale for continued investigation into the therapeutic potential of cannabinoids.

Identification of ∆9-tetrahydrocannabinol (THC) impairment using functional brain imaging

The primary cannabinoid in cannabis, Δ9-tetrahydrocannabinol (THC), causes intoxication and impaired function, with implications for traffic, workplace, and other situational safety risks. There are currently no evidence-based methods to detect cannabis-impaired driving, and current field sobriety tests with gold-standard, drug recognition evaluations are resource-intensive and may be prone to bias. This study evaluated the capability of a simple, portable imaging method to accurately detect individuals with THC impairment. In this double-blind, randomized, cross-over study, 169 cannabis users, aged 18-55 years, underwent functional near-infrared spectroscopy (fNIRS) before and after receiving oral THC and placebo, at study visits one week apart. Impairment was defined by convergent classification by consensus clinical ratings and an algorithm based on post-dose tachycardia and self-rated "high." Our primary outcome, prefrontal cortex (PFC) oxygenated hemoglobin concentration (HbO), was increased after THC only in participants operationalized as impaired, independent of THC dose. ML models using fNIRS time course features and connectivity matrices identified impairment with 76.4% accuracy, 69.8% positive predictive value (PPV), and 10% false-positive rate using convergent classification as ground truth, which exceeded Drug Recognition Evaluator-conducted expanded field sobriety examination (67.8% accuracy, 35.4% PPV, and 35.4% false-positive rate). These findings demonstrate that PFC response activation patterns and connectivity produce a neural signature of impairment, and that PFC signal, measured with fNIRS, can be used as a sole input to ML models to objectively determine impairment from THC intoxication at the individual level. Future work is warranted to determine the specificity of this classifier to acute THC impairment.ClinicalTrials.gov Identifier: NCT03655717.

Functional brain connectomes reflect acute and chronic cannabis use

Resting state fMRI has been employed to identify alterations in functional connectivity within or between brain regions following acute and chronic exposure to Δ9-tetrahydrocannabinol (THC), the psychoactive component in cannabis. Most studies focused a priori on a limited number of local brain areas or circuits, without considering the impact of cannabis on whole-brain network organization. The present study attempted to identify changes in the whole-brain human functional connectome as assessed with ultra-high field (7T) resting state scans of cannabis users (N = 26) during placebo and following vaporization of cannabis. Two distinct data-driven methodologies, i.e. network-based statistics (NBS) and connICA, were used to identify changes in functional connectomes associated with acute cannabis intoxication and history of cannabis use. Both methodologies revealed a broad state of hyperconnectivity within the entire range of major brain networks in chronic cannabis users compared to occasional cannabis users, which might be reflective of an adaptive network reorganization following prolonged cannabis exposure. The connICA methodology also extracted a distinct spatial connectivity pattern of hypoconnectivity involving the dorsal attention, limbic, subcortical and cerebellum networks and of hyperconnectivity between the default mode and ventral attention network, that was associated with the feeling of subjective high during THC intoxication. Whole-brain network approaches identified spatial patterns in functional brain connectomes that distinguished acute from chronic cannabis use, and offer an important utility for probing the interplay between short and long-term alterations in functional brain dynamics when progressing from occasional to chronic use of cannabis.

Digital Medical Cannabis as Market Differentiator: Second-Generation Artificial Intelligence Systems to Improve Response

Legalized use of cannabis products and the rising interest in their therapeutic benefits have opened up new opportunities for therapy and marketing. However, the marked variability in formulations, administration modes, therapeutic regimens, and inter- and intra-subject responses make the standardization of medical cannabis-based regimens difficult. Legalization has made the cannabis market highly competitive and lowered the revenue margins. This study reviews some of the challenges in medical cannabis use and difficulties in standardizing its therapeutic regimens that hinder maximizing its beneficial effects. The development of tolerance toward cannabis and low adherence to chronic administration further impair its long-term beneficial effects. Digital medical cannabis is a cannabis product controlled by a second-generation artificial intelligence (AI) system that improves patient responses by increasing adherence and dealing with tolerance. Second-generation AI systems focus on a single patient's outcome and deal with the inter- and intra-subject variability in responses. The use of digital medical cannabis is expected to improve product standardization, maximize therapeutic benefits, reduce health care costs, and increase the revenue of companies. Digital medical cannabis offers several market differentiators for cannabis companies. This study presents a model for promoting the use of digital medical cannabis and presents its advantages for patients, clinicians, health care authorities, insurance companies, and cannabis manufacturers. Ongoing trials and real-world data on the use of these systems further support the use of digital medical cannabis for improved global health.

A Clinical Framework for Assessing Cannabis-Related Impairment Risk

Clinicians play an important role in promoting safe and responsible medical cannabis use. One essential component to safe use is considering a patient's risk of neurocognitive impairment. However, there remains a lack of practical guidance on how clinicians can evaluate this risk for medical cannabis patients. Here, a practical framework is presented for clinicians to assess and stratify cannabis-associated impairment risk. The proposed framework is intended to practically guide healthcare providers in gaining a more comprehensive review of a patient's impairment-related factors. This framework can be used to assess impairment risk for patients currently using or considering medical cannabis and is recommended for all patients who perform safety-sensitive duties. Healthcare providers (HCP) managing patient's medical cannabis or those conducting assessments to determine risk of impairment for safety-sensitive workplaces can utilize this framework to stratify patients' risk of impairment. Such assessments can inform patient-specific needs for support, education, and guidance, to ensure cannabis is used safely and responsibly.

Cannabis Use and Neuroadaptation: A Call for Δ 9 -Tetrahydrocannabinol Challenge Studies

Currently, the assessment of the neurobehavioral consequences of repeated cannabis use is restricted to studies in which brain function of chronic cannabis users is compared to that of non-cannabis using controls. The assumption of such studies is that changes in brain function of chronic users are caused by repeated and prolonged exposure to acute cannabis intoxication. However, differences in brain function between chronic cannabis users and non-users might also arise from confounding factors such as polydrug use, alcohol use, withdrawal, economic status, or lifestyle conditions. We propose a methodology that highlights the relevance of acute Δ⁹-tetrahydrocannabinol (THC) dosing studies for a direct assessment of neuroadaptations in chronic cannabis users. The approach includes quantification of neurochemical, receptor, and functional brain network changes in response to an acute cannabis challenge, as well as stratification of cannabis using groups ranging from occasional to cannabis-dependent individuals. The methodology allows for an evaluation of THC induced neuroadaptive and neurocognitive changes across cannabis use history, that can inform neurobiological models on reward driven, compulsive cannabis use.

Lower-Risk Cannabis Use Guidelines (LRCUG) for reducing health harms from non-medical cannabis use: A comprehensive evidence and recommendations update

BACKGROUND

Cannabis use is common, especially among young people, and is associated with risks for various health harms. Some jurisdictions have recently moved to legalization/regulation pursuing public health goals. Evidence-based 'Lower Risk Cannabis Use Guidelines' (LRCUG) and recommendations were previously developed to reduce modifiable risk factors of cannabis-related adverse health outcomes; related evidence has evolved substantially since. We aimed to review new scientific evidence and to develop comprehensively up-to-date LRCUG, including their recommendations, on this evidence basis.

METHODS

Targeted searches for literature (since 2016) on main risk factors for cannabis-related adverse health outcomes modifiable by the user-individual were conducted. Topical areas were informed by previous LRCUG content and expanded upon current evidence. Searches preferentially focused on systematic reviews, supplemented by key individual studies. The review results were evidence-graded, topically organized and narratively summarized; recommendations were developed through an iterative scientific expert consensus development process.

RESULTS

A substantial body of modifiable risk factors for cannabis use-related health harms were identified with varying evidence quality. Twelve substantive recommendation clusters and three precautionary statements were developed. In general, current evidence suggests that individuals can substantially reduce their risk for adverse health outcomes if they delay the onset of cannabis use until after adolescence, avoid the use of high-potency (THC) cannabis products and high-frequency/-intensity of use, and refrain from smoking-routes for administration. While young people are particularly vulnerable to cannabis-related harms, other sub-groups (e.g., pregnant women, drivers, older adults, those with co-morbidities) are advised to exercise particular caution with use-related risks. Legal/regulated cannabis products should be used where possible.

CONCLUSIONS

Cannabis use can result in adverse health outcomes, mostly among sub-groups with higher-risk use. Reducing the risk factors identified can help to reduce health harms from use. The LRCUG offer one targeted intervention component within a comprehensive public health approach for cannabis use. They require effective audience-tailoring and dissemination, regular updating as new evidence become available, and should be evaluated for their impact.

An initial analysis of the UK Medical Cannabis Registry: Outcomes analysis of first 129 patients

AIM

Cannabis-based medicinal products (CBMPs) are prescribed with increased frequency, despite a paucity of high-quality randomized controlled trials. The aim of this study is to analyze the early outcomes of the first series of patients prescribed CBMPs in the UK with respect to effects on health-related quality of life and clinical safety.

METHODS

A prospective case series was performed using the UK Medical Cannabis Registry. Primary outcomes were change in patient-reported outcomes measures (EQ-5D-5L, General Anxiety Disorder-7 (GAD-7) and Single-Item Sleep Quality Scale (SQS)) at 1 and 3 months from baseline. The secondary outcome was the incidence of adverse events. Statistical significance was defined by a P-value <.050.

RESULTS

There were 129 patients included in the final analysis with a mean age of 46.23 (±14.51) years. The most common indication was chronic pain of undefined etiology (n = 48; 37.2%). The median initial cannabidiol and (-)-trans-Δ⁹-tetrahydrocannabinol daily dose was 20.0 mg (Range: 0.0-768.0 mg) and 3.9 mg (Range: 0.0-660.0 mg), respectively. Statistically significant improvements in health-related quality of life were demonstrated at 1 and 3 months in GAD-7, SQS, EQ-5D-5L pain and discomfort subscale, EQ-5D-5L anxiety and depression subscale, EQ-VAS and EQ-5D-5L index values(P < .050). There were 31 (24.03%) total reported adverse events.

CONCLUSION

This study suggests that CBMP therapy may be associated with an improvement in health-related quality-of-life outcomes as self-reported by patients. CBMPs are also demonstrated to be relatively safe in the short to medium-term. These findings must be treated with caution given the limited scope of this initial analysis, with no placebo or an active comparator, with further research required.

Medicinal cannabis and driving: the intersection of health and road safety policy

BACKGROUND

Recent shifting attitudes towards the medical use of cannabis has seen legal access pathways established in many jurisdictions in North America, Europe and Australasia. However, the positioning of cannabis as a legitimate medical product produces some tensions with other regulatory frameworks. A notable example of this is the so-called 'zero tolerance' drug driving legal frameworks, which criminalise the presence of THC (tetrahydrocannabinol) in a driver's bodily fluids irrespective of impairment. Here we undertake an analysis of this policy issue based on a case study of the introduction of medicinal cannabis in Australia.

METHODS

We examine the regulatory approaches used for managing road safety risks associated with potentially impairing prescription medicines and illicit drugs in Australian jurisdictions, as well as providing an overview of evidence relating to cannabis and road safety risk, unintended impacts of the 'zero-tolerance' approach on patients, and the regulation of medicinal cannabis and driving in comparable jurisdictions.

RESULTS

Road safety risks associated with medicinal cannabis appear similar or lower than numerous other potentially impairing prescription medications. The application of presence-based offences to medicinal cannabis patients appears to derive from the historical status of cannabis as a prohibited drug with no legitimate medical application. This approach is resulting in patient harms including criminal sanctions when not impaired and using the drug as directed by their doctor, or the forfeiting of car use and related mobility. Others who need to drive are excluded from accessing a needed medication and associated therapeutic benefit. 'Medical exemptions' for medicinal cannabis in comparable jurisdictions and other drugs included in presence offences in Australia (e.g. methadone) demonstrate a feasible alternative approach.

CONCLUSION

We conclude that in medical-only access models there is little evidence to justify the differential treatment of medicinal cannabis patients, compared with those taking other prescription medications with potentially impairing effects.

The why behind the high: determinants of neurocognition during acute cannabis exposure

Acute cannabis intoxication may induce neurocognitive impairment and is a possible cause of human error, injury and psychological distress. One of the major concerns raised about increasing cannabis legalization and the therapeutic use of cannabis is that it will increase cannabis-related harm. However, the impairing effect of cannabis during intoxication varies among individuals and may not occur in all users. There is evidence that the neurocognitive response to acute cannabis exposure is driven by changes in the activity of the mesocorticolimbic and salience networks, can be exacerbated or mitigated by biological and pharmacological factors, varies with product formulations and frequency of use and can differ between recreational and therapeutic use. It is argued that these determinants of the cannabis-induced neurocognitive state should be taken into account when defining and evaluating levels of cannabis impairment in the legal arena, when prescribing cannabis in therapeutic settings and when informing society about the safe and responsible use of cannabis.

Cannabis and driving ability

The aim of this review is to discuss recent evidence on cannabis and driving ability. In particular, the review examines experimental research on the acute effects of tetrahydrocannabinol (THC) on driving-related neurobehavioral skills and driving performance based on simulator and road course studies. The evidence indicates that certain driving abilities are significantly, albeit modestly, impaired in individuals experiencing the acute effects of THC. Treatment effects are moderated by dose, delivery method, recency of use, and tolerance development, with inconclusive evidence concerning the moderating influence of cannabidiol. Emerging research priorities include linking neurobehavioral deficits to specific decrements in driving performance, estimating the real-world implications of experimental impaired driving research, understanding how tolerance differentially affects driving impairment across subgroups, and developing more evidence on cannabidiol's potential role in mitigating THC-induced impairment.

Intoxication by a synthetic cannabinoid (JWH-018) causes cognitive and psychomotor impairment in recreational cannabis users

BACKGROUND

Smoking mixtures containing synthetic cannabinoids (SCs) have become very popular over the last years but pose a serious risk for public health. Limited knowledge is, however, available regarding the acute effects of SCs on cognition and psychomotor performance. Earlier we demonstrated signs of impairment in healthy volunteers after administering one of the first SCs, JWH-018, even though subjective intoxication was low. In the current study, we aimed to investigate the acute effects of JWH-018 on several cognitive and psychomotor tasks in participants who are demonstrating representative levels of acute intoxication.

METHODS

24 healthy cannabis-experienced participants took part in this placebo-controlled, cross-over study. Participants inhaled the vapor of 75 μg JWH-018/kg body weight and were given a booster dose if needed to induce a minimum level of subjective high. They were subsequently monitored for 4 h, during which psychomotor and cognitive performance, vital signs, and subjective experience were measured, and serum concentrations were determined.

RESULTS

Maximum subjective high (average 64%) was reached 30 min after administration of JWH-018, while the maximum blood concentration was shown after 5 min (8 ng/mL). JWH-018 impaired motor coordination (CTT), attention (DAT and SST), memory (SMT), it lowered speed-accuracy efficiency (MFFT) and slowed down response speed (DAT).

CONCLUSION

In accordance with our previous studies, we demonstrated acute psychomotor and cognitive effects of a relatively low dose of JWH-018.

Determining the magnitude and duration of acute Δ9-tetrahydrocannabinol (Δ9-THC)-induced driving and cognitive impairment: A systematic and meta-analytic review

The increasing legal availability of cannabis has important implications for road safety. This systematic review characterised the acute effects of Δ⁹-THC on driving performance and driving-related cognitive skills, with a particular focus on the duration of Δ⁹-THC-induced impairment. Eighty publications and 1534 outcomes were reviewed. Several measures of driving performance and driving-related cognitive skills (e.g. lateral control, tracking, divided attention) demonstrated impairment in meta-analyses of "peak" Δ⁹-THC effects (p's<0.05). Multiple meta-regression analyses further found that regular cannabis users experianced less impairment than 'other' (mostly occasional) cannabis users (p = 0.003) and that the magnitude of oral (n = 243 effect estimates [EE]) and inhaled (n = 481 EEs) Δ⁹-THC-induced impairment depended on various factors (dose, post-treatment time interval, the performance domain (skill) assessed) in other cannabis users (p's<0.05). The latter model predicted that most driving-related cognitive skills would 'recover' (Hedges' g=-0.25) within ∼5-hs (and almost all within ∼7-hs) of inhaling 20 mg of Δ⁹-THC; oral Δ⁹-THC-induced impairment may take longer to subside. These results suggest individuals should wait at least 5 -hs following inhaled cannabis use before performing safety-sensitive tasks.

Effect of Cannabidiol and Δ9-Tetrahydrocannabinol on Driving Performance: A Randomized Clinical Trial

IMPORTANCE

Cannabis use has been associated with increased crash risk, but the effect of cannabidiol (CBD) on driving is unclear.

OBJECTIVE

To determine the driving impairment caused by vaporized cannabis containing Δ9-tetrahydrocannabinol (THC) and CBD.

DESIGN, SETTING, AND PARTICIPANTS

A double-blind, within-participants, randomized clinical trial was conducted at the Faculty of Psychology and Neuroscience at Maastricht University in the Netherlands between May 20, 2019, and March 27, 2020. Participants (N = 26) were healthy occasional users of cannabis.

INTERVENTIONS

Participants vaporized THC-dominant, CBD-dominant, THC/CBD-equivalent, and placebo cannabis. THC and CBD doses were 13.75 mg. Order of conditions was randomized and balanced.

MAIN OUTCOMES AND MEASURES

The primary end point was standard deviation of lateral position (SDLP; a measure of lane weaving) during 100 km, on-road driving tests that commenced at 40 minutes and 240 minutes after cannabis consumption. At a calibrated blood alcohol concentration (BAC) of 0.02%, SDLP was increased relative to placebo by 1.12 cm, and at a calibrated BAC of 0.05%, SDLP was increased relative to placebo by 2.4 cm.

RESULTS

Among 26 randomized participants (mean [SD] age, 23.2 [2.6] years; 16 women), 22 (85%) completed all 8 driving tests. At 40 to 100 minutes following consumption, the SDLP was 18.21 cm with CBD-dominant cannabis, 20.59 cm with THC-dominant cannabis, 21.09 cm with THC/CBD-equivalent cannabis, and 18.28 cm with placebo cannabis. SDLP was significantly increased by THC-dominant cannabis (+2.33 cm [95% CI, 0.80 to 3.86]; P < .001) and THC/CBD-equivalent cannabis (+2.83 cm [95% CI, 1.28 to 4.39]; P < .001) but not CBD-dominant cannabis (-0.05 cm [95% CI, -1.49 to 1.39]; P > .99), relative to placebo. At 240 to 300 minutes following consumption, the SDLP was 19.03 cm with CBD-dominant cannabis, 19.88 cm with THC-dominant cannabis, 20.59 cm with THC/CBD-equivalent cannabis, and 19.37 cm with placebo cannabis. The SDLP did not differ significantly in the CBD (-0.34 cm [95% CI, -1.77 to 1.10]; P > .99), THC (0.51 cm [95% CI, -1.01 to 2.02]; P > .99) or THC/CBD (1.22 cm [95% CI, -0.29 to 2.72]; P = .20) conditions, relative to placebo. Out of 188 test drives, 16 (8.5%) were terminated due to safety concerns.

CONCLUSIONS AND RELEVANCE

In a crossover clinical trial that assessed driving performance during on-road driving tests, the SDLP following vaporized THC-dominant and THC/CBD-equivalent cannabis compared with placebo was significantly greater at 40 to 100 minutes but not 240 to 300 minutes after vaporization; there were no significant differences between CBD-dominant cannabis and placebo. However, the effect size for CBD-dominant cannabis may not have excluded clinically important impairment, and the doses tested may not represent common usage.

TRIAL REGISTRATION

EU Clinical Trials Register: 2018-003945-40.