Evaluation of divided attention psychophysical task performance and effects on pupil sizes following smoked, vaporized and oral cannabis administration

Narcotic Nitrogen Effects Persist after a Simulated Deep Dive

Background and Objectives: Scuba divers often experience persistent inert gas narcosis (IGN) even after surfacing. This study aimed to test the hypothesis that breathing oxygen (O2) before surfacing can reduce postdive IGN. Materials and Methods: A group of 58 experienced divers underwent a 5 min dive at a depth of 50 m in a multi-place hyperbaric chamber. They were decompressed using air (air group). Another group of 28 divers (O2 group) breathed 100% O2 during the end of decompression. Prior to and after the dive, all participants performed the Sharpened Romberg test (SRT) and a modified tweezers test. Results: In the air group, the number of positive SRT results increased postdive (47% vs. 67%), indicating a greater impairment in the vestibular system (Cohen's d = 0.41). In the O2 group, the percentage of positive SRT results remained constant at 68% both before and after the dive. In terms of the modified tweezers test, the air group showed no significant change in the number of picked beads (40 ± 9 vs. 39 ± 7), while the O2 group demonstrated an increase (36 ± 7 vs. 44 ± 10) (Cohen's d = 0.34). Conclusion: The results reveal that the SRT revealed a negative effect of nitrogen (N2) on the vestibular system in the air group. The increased number of beads picked in the O2 group can be attributed to the learning effect, which was hindered in the air group. Consistent with our hypothesis, breathing O2 during decompression appears to reduce postdive IGN.

The effect of cannabis edibles on driving and blood THC

BACKGROUND

Cannabis has been shown to impact driving due to changes produced by delta-9-tetrahydrocannabinol (THC), the psychoactive component of cannabis. Current legal thresholds for blood THC while driving are based predominantly on evidence utilizing smoked cannabis. It is known that levels of THC in blood are lower after eating cannabis as compared to smoking yet the impact of edibles on driving and associated blood THC has never been studied.

METHODS

Participants drove a driving simulator before and after ingesting their preferred legally purchased cannabis edible. In a counterbalanced control session, participants did not consume any THC or cannabidiol (CBD). Blood was collected for measurement of THC and metabolites as well as CBD. Subjective experience was also assessed.

RESULTS

Participants consumed edibles with, on average, 7.3 mg of THC, which is less than the maximum amount available in a single retail package in Ontario, providing an ecologically valid test of cannabis edibles. Compared to control, cannabis edibles produced a decrease in mean speed 2 h after consumption but not at 4 and 6 h. Under dual task conditions in which participants completed a secondary task while driving, changes in speed were not significant after the correction for multiple comparison. No changes in standard deviation of lateral position (SDLP; 'weaving'), maximum speed, standard deviation of speed or reaction time were found at any time point or under either standard or dual task conditions. Mean THC levels were significantly increased, relative to control, after consuming the edible but remained relatively low at approximately 2.8 ng/mL 2 h after consumption. Driving impairment was not correlated with blood THC. Subjective experience was altered for 7 h and participants were less willing/able to drive for up to 6 h, suggesting that the edible was intoxicating.

INTERPRETATION

This is the first study of the impact of cannabis edibles on simulated driving. Edibles were intoxicating as revealed by the results of subjective assessments (VAS), and there was some impact on driving. Detection of driving impairment after the use of cannabis edibles may be difficult.

Effects of recent cannabis consumption on eye-tracking and pupillometry

Introduction

Cannabis consumption is known to immediately affect ocular and oculomotor function, however, cannabis consumption is also known to affect it for a prolonged period of time. The purpose of this study is to identify an eye tracking or pupillometry metric which is affected after recent cannabis consumption but is not confounded by cannabis consumption history or demographic variables.

Methods

Quasi-experimental design. Participants who would consume inhalable cannabis (n = 159, mean age 31.0 years, 54% male) performed baseline neurobehavioral testing and eye-function assessments when they were sober. Eye function assessments included eye-tracking [gaze (point of visual focus), saccades (smooth movement)] and pupillometry. Participants then inhaled cannabis until they self-reported to be high and performed the same assessment again. Controls who were cannabis naïve or infrequent users (n = 30, mean age 32.6 years, 57% male) performed the same assessments without consuming cannabis in between.

Results

Cannabis significantly affected several metrics of pupil dynamics and gaze. Pupil size variability was the most discriminant variable after cannabis consumption. This variable did not change in controls on repeat assessment (i.e., no learning effect), did not correlate with age, gender, race/ethnicity, or self-reported level of euphoria, but did correlate with THC concentration of cannabis inhaled.

Discussion

A novel eye-tracking metric was identified that is affected by recent cannabis consumption and is not different from non-users at baseline. A future study that assesses pupil size variability at multiple intervals over several hours and quantifies cannabis metabolites in biofluids should be performed to identify when this variable normalizes after consumption and if it correlates with blood THC levels.

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 Video Segmentation Pipeline for Assessing changes in Pupil Response to Light After Cannabis Consumption

Due to long-standing federal restrictions on cannabis-related research, the implications of cannabis legalization on traffic and occupational safety are understudied. Accordingly, there is a need for objective and validated measures of acute cannabis impairment that may be applied in public safety and occupational settings. Pupillary response to light may offer an avenue for detection that outperforms typical sobriety tests and THC concentrations. We developed a video processing and analysis pipeline that extracts pupil sizes during a light stimulus test administered with goggles utilizing infrared videography. The analysis compared pupil size trajectories in response to a light for those with occasional, daily, and no cannabis use before and after smoking. Pupils were segmented using a combination of image pre-processing techniques and segmentation algorithms which were validated using manually segmented data and found to achieve 99% precision and 94% F-score. Features extracted from the pupil size trajectories captured pupil constriction and rebound dilation and were analyzed using generalized estimating equations. We find that acute cannabis use results in less pupil constriction and slower pupil rebound dilation in the light stimulus test.

Eye tracking: empirical foundations for a minimal reporting guideline

In this paper, we present a review of how the various aspects of any study using an eye tracker (such as the instrument, methodology, environment, participant, etc.) affect the quality of the recorded eye-tracking data and the obtained eye-movement and gaze measures. We take this review to represent the empirical foundation for reporting guidelines of any study involving an eye tracker. We compare this empirical foundation to five existing reporting guidelines and to a database of 207 published eye-tracking studies. We find that reporting guidelines vary substantially and do not match with actual reporting practices. We end by deriving a minimal, flexible reporting guideline based on empirical research (Section "An empirically based minimal reporting guideline").

Adjunctive Management of Opioid Withdrawal with the Nonopioid Medication Cannabidiol

Introduction: Opioid use disorder (OUD) is a major public health crisis worldwide. Patients with OUD inevitably experience withdrawal symptoms when they attempt to taper down on their current opioid use, abstain completely from opioids, or attempt to transition to certain medications for opioid use disorder. Acute opioid withdrawal can be debilitating and include a range of symptoms such as anxiety, pain, insomnia, and gastrointestinal symptoms. Whereas acute opioid withdrawal only lasts for 1-2 weeks, protracted withdrawal symptoms can persist for months after the cessation of opioids. Insufficient management of opioid withdrawal often leads to devastating results including treatment failure, relapse, and overdose. Thus, there is a critical need for cost-effective, nonopioid medications, with minimal side effects to help in the medical management of opioid withdrawal syndrome. We discuss the potential consideration of cannabidiol (CBD), a nonintoxicating component of the cannabis plant, as an adjunctive treatment in managing the opioid withdrawal syndrome. Materials and Methods: A review of the literature was performed using keywords related to CBD and opioid withdrawal syndrome in PubMed and Google Scholar. A total of 144 abstracts were identified, and 41 articles were selected where CBD had been evaluated in clinical studies relevant to opioid withdrawal. Results: CBD has been reported to have several therapeutic properties including anxiolytic, antidepressant, anti-inflammatory, anti-emetic, analgesic, as well as reduction of cue-induced craving for opioids, all of which are highly relevant to opioid withdrawal syndrome. In addition, CBD has been shown in several clinical trials to be a well-tolerated with no significant adverse effects, even when co-administered with a potent opioid agonist. Conclusions: Growing evidence suggests that CBD could potentially be added to the standard opioid detoxification regimen to mitigate acute or protracted opioid withdrawal-related symptoms. However, most existing findings are either based on preclinical studies and/or small clinical trials. Well-designed, prospective, randomized-controlled studies evaluating the effect of CBD on managing opioid withdrawal symptoms are warranted.

Perceived effects of cannabis: Generalizability of changes in driving performance

OBJECTIVE

The objective of this analysis was to determine the generalizability of the relationship between different samples of a driver's perceived state after cannabis use and related performance while operating a motor vehicle.

METHODS

Data were collected from 52 subjects in a study examining the effects of cannabis on driving performance. Data were analyzed using the SAS GLM Select procedure, using stepwise selection, with subjective effects, dosing condition (placebo vs. 6.18% delta-9-tetrahydrocannabinol [THC]), and driving context as independent measures. Correlation matrices of measures of driving performance against subjective responses and dosing condition used Pearson's and Spearman's test statistics, respectively. Results were compared to a prior study from a sample of 10 subjects.

RESULTS

Subjective perceptions of acute cannabis impairment remain significant predictors of driving performance and explain individual variability in driving performance degradation as well as the data, beyond that which can be explained by acute use of cannabis alone. However, the significant subjective predictors of driving performance differ between the current and prior studies. To better understand these differences, correlations between subjective effects and performance measures were evaluated, which revealed that most correlations matched directionally (e.g., an increase in "good drug effect" was correlated with an increase in standard deviation of lane position [SDLP]). When there was a mismatch, 1 or more correlations were insignificant. Dosing condition and "stoned" were perfectly consistent; "high" and "sedated" contained 1 mismatch; and "anxious," "good drug effect" and "restless" contained 3 or more mismatches.

CONCLUSIONS

The results indicate that across both studies, differences in the perceived effects of cannabis are reflected in changes in both lateral and longitudinal control beyond the acute effects of cannabis, which may help explain individual variability in response to acute intoxication. However, the generalizability of these findings is lacking, as shown by inconsistencies in when and where subjective effects were significant. Other factors such as frequency of use, usage type, the evolving profile of a cannabis user, as well as other individual differences should be considered to explain this additional variability.

Mechanisms of cannabis impairment: Implications for modeling driving performance

Past research on cannabis has been limited in scope to THC potencies lower than legally available and efforts to integrate the effects into models of driving performance have not been attempted to date. The purpose of this systematic review is to understand the implications for modeling driving performance and describe future research needs. The risk of motor vehicle crashes increases 2-fold after smoking marijuana. Driving during acute cannabis intoxication impairs concentration, reaction time, along with a variety of other necessary driving-related skills. Changes to legislation in North America and abroad have led to an increase in cannabis' popularity. This has given rise to more potent strains, with higher THC concentrations than ever before. There is also rising usage of novel ingestion methods other than smoking, such as oral cannabis products (e.g., brownies, infused drinks, candies), vaping, and topicals. The PRISMA guidelines were followed to perform a systematic search of the PubMed database for peer-reviewed literature. Search terms were combined with keywords for driving performance: driving, performance, impairment. Grey literature was also reviewed, including congressional reports, committee reports, and roadside surveys. There is a large discrepancy between the types of cannabis products sold and what is researched. Almost all studies that used inhalation as the mode of ingestion with cannabis that is around 6% THC. This pales in comparison to the more potent strains being sold today which can exceed 20%. Which is to say nothing of extracts, which can contain 60% or more THC. Experimental protocol is another gap in research that needs to be filled. Methodologies that involve naturalistic (real world) driving environments, smoked rather than vaporized cannabis, and non-lab certified products introduce uncontrollable variables. When considering the available literature and the implications of modeling the impacts of cannabis on driving performance, two critical areas emerge that require additional research: The first is the role of cannabis potency. Second is the route of administration. Does the lower peak THC level result in smaller impacts on performance? How long does potential impairment last along the longer time-course associated with different pharmacokinetic profiles. It is critical for modeling efforts to understand the answers to these questions, accurately model the effects on driver performance, and by extension understand the risk to the public.

Are vaporizers a lower-risk alternative to smoking cannabis?

Cannabis use is associated with various adverse physical and mental health outcomes as well as increased risk of motor vehicle collision. Many organizations and the "Lower-Risk Cannabis Use Guidelines" have recommended to use cannabis vaporizers instead of smoking to reduce the associated health risk. This commentary draws attention to the present evidence regarding harm reduction potential of cannabis vaping. Cannabis vaporizer use can reduce the emission of carbon monoxide, chronic respiratory symptoms, and exposure to several toxins while producing similar subjective effects and blood THC concentration compared with smoking cannabis, holding potential for harm reduction among habitual cannabis smokers. However, new cannabis users, regardless of method of administration of cannabis, may experience intense subjective effects and cognitive impairment with increased susceptibility to dependence. Hence, policy makers should consider limiting access to cannabis among young people and adopting strategies to reduce impaired driving under influence of cannabis. Future research should focus on impact of switching from cannabis smoking to dried herb vaping using cannabis vaporizers among chronic cannabis smokers, and long-term outcomes of medical cannabis vaping, and further explore association of vaping-associated lung injury with THC-containing e-liquids.

Preliminary Eye-Tracking Data as a Nonintrusive Marker for Blood Δ-9-Tetrahydrocannabinol Concentration and Drugged Driving

Background: Cannabis is one of the drugs most often found in drivers involved in serious motor vehicle collisions. Validity and reliability of roadside cannabis detection strategies are questioned. This pilot study aimed to investigate the relationship between eye characteristics and cannabis effects in simulated driving to inform potential development of an alternative detection strategy. Materials and Methods: Multimodal data, including blood samples, eye-tracking recordings, and driving performance data, were acquired from 10 participants during a prolonged single-session driving simulator experiment. The study session included a baseline driving trial before cannabis exposure and seven trials at various times over ∼5 h after exposure. The multidimensional eye-tracking recording from each driving trial for each participant was segmented into nonoverlapping epochs (time windows); 34 features were extracted from each epoch. Blood Δ-9-tetrahydrocannabinol (THC) concentration, standard deviation of lateral position (SDLP), and mean vehicle speed were target variables. The cross-correlation between the temporal profile of each eye-tracking feature and target variable was assessed and a nonlinear regression analysis evaluated temporal trend of features following cannabis exposure. Results: Mean pupil diameter (r=0.81-0.86) and gaze pitch angle standard deviation (r=0.79-0.87) were significantly correlated with blood THC concentration (p<0.01) for all epoch lengths. For driving performance variables, saccade-related features were among those showing the most significant correlation (r=0.61-0.83, p<0.05). Epoch length significantly affected correlations between eye-tracking features and speed (p<0.05), but not SDLP or blood THC concentration (p>0.1). Temporal trend analysis of eye-tracking features after cannabis also showed a significant increasing trend (p<0.01) in saccade-related features, including velocity, scanpath, and duration, as the influence of cannabis decreased by time. A decreasing trend was observed for fixation percentage and mean pupil diameter. Due to the lack of placebo control in this study, these results are considered preliminary. Conclusion: Specific eye characteristics could potentially be used as nonintrusive markers of THC presence and driving-related effects of cannabis. clinicaltrials.gov (NCT03813602).

Assessment of cognitive and psychomotor impairment, subjective effects, and blood THC concentrations following acute administration of oral and vaporized cannabis

BACKGROUND

Cannabis legalization is expanding, but there are no established methods for detecting cannabis impairment.

AIM

Characterize the acute impairing effects of oral and vaporized cannabis using various performance tests.

METHODS

Participants (N = 20, 10 men/10 women) who were infrequent cannabis users ingested cannabis brownies (0, 10, and 25 mg Δ-9-tetrahydrocannabinol, THC) and inhaled vaporized cannabis (0, 5, and 20 mg THC) in six double-blind outpatient sessions. Cognitive/psychomotor impairment was assessed with a battery of computerized tasks sensitive to cannabis effects, a novel test (the DRiving Under the Influence of Drugs, DRUID®), and field sobriety tests. Blood THC concentrations and subjective drug effects were evaluated.

RESULTS

Low oral/vaporized doses did not impair cognitive/psychomotor performance relative to placebo but produced positive subjective effects. High oral/vaporized doses impaired cognitive/psychomotor performance and increased positive and negative subjective effects. The DRUID® was the most sensitive test to cannabis impairment, as it detected significant differences between placebo and active doses within both routes of administration. Women displayed more impairment on the DRUID® than men at the high vaporized dose only. Field sobriety tests showed little sensitivity to cannabis-induced impairment. Blood THC concentrations were far lower after cannabis ingestion versus inhalation. After inhalation, blood THC concentrations typically returned to baseline well before pharmacodynamic effects subsided.

CONCLUSIONS

Standard approaches for identifying impairment due to cannabis exposure (i.e. blood THC and field sobriety tests) have severe limitations. There is a need to identify novel biomarkers of cannabis exposure and/or behavioral tests like the DRUID® that can reliably and accurately detect cannabis impairment at the roadside and in the workplace.

Preliminary Evidence for Cannabis and Nicotine Urinary Metabolites as Predictors of Verbal Memory Performance and Learning Among Young Adults

OBJECTIVE

Verbal memory deficits are linked to cannabis use. However, self-reported episodic use does not allow for assessment of variance from other factors (e.g., cannabis potency, route of consumption) that are important for assessing brain-behavior relationships. Further, co-occurring nicotine use may moderate the influence of cannabis on cognition. Here we utilized objective urinary measurements to assess the relationship between metabolites of cannabis, 11-nor-9-carboxy-∆9-tetrahydrocannabinol (THCCOOH), and nicotine (cotinine) on verbal memory in young adults.

METHOD

Adolescents and young adults (n = 103) aged 16-22 completed urinary drug testing and verbal memory assessment (RAVLT). Linear regressions examined the influence of THCCOOH and cotinine quantitative concentrations, and their interaction, on RAVLT scores, controlling for demographics and alcohol. Cannabis intake frequency was also investigated. Secondary analyses examined whether past month or recency of use related to performance, while controlling for THCCOOH and cotinine concentrations.

RESULTS

THCCOOH concentration related to both poorer total learning and long delay recall. Cotinine concentration related to poorer short delay recall. Higher frequency cannabis use status was associated with poorer initial learning and poorer short delay. When comparing to self-report, THCCOOH and cotinine concentrations were negatively related to learning and memory performance, while self-report was not.

CONCLUSIONS

Results confirm the negative relationship between verbal memory and cannabis use, extending findings with objective urinary THCCOOH, and cotinine concentration measurements. No moderating relationship with nicotine was found, though cotinine concentration independently associated with negative short delay performance. Findings support the use of both urinary and self-report metrics as complementary methods in substance use research.

Perceived effects of cannabis and changes in driving performance under the influence of cannabis

OBJECTIVE

Reports indicate that cannabis users will adapt their driving to compensate for the perceived drug effects of cannabis. This analysis examined the relationship between driver perceptions of their state contrasted with objective measures of their performance while operating a motor vehicle.

METHODS

Data was collected from ten subjects in a study examining the effects of cannabis on driving performance. Driving performance was collected on the NADS quarter-cab miniSim, a limited field of view non-motion simulator, approximately two hours after cannabis inhalation. Driving measures of both lateral and longitudinal control were included in our analysis. Subjective measures of the effects of cannabis were collected at peak and prior to driving, using visual analog scales. Data were analyzed using the SAS GLM Select procedure with subjective effect, dosing condition (placebo vs 6.9% THC), and driving event as independent measures. The stepwise selection method was used.

RESULTS

The analysis of each of the subjective effects showed significant differences between the placebo and the active cannabis dosed conditions. While we found variance in difference between group means, there was greater variability between subject values. We found that subjective measures were predictive of variance in driver inputs, such as steering frequency and steering reversal rate. Variance in SDLP and other driving performance measures, however, were predicted by dosing condition.

CONCLUSIONS

Overall, some of the effects perceived by the driver were better related to changes in driver inputs rather than the presence of cannabis itself. Changes in performance measures such as SDLP are better explained by dosing condition. Thus, driver's perceptions may result in changes to driving behavior that could mitigate the effect of cannabis. For both lateral and longitudinal control, an increasing perception of stimulation produced a positive effect on performance. Our results provide a better understanding of how different strains of cannabis, which produce different subjective experiences for users, could impact driving safety. Specifically, we found drug effects that produce more stimulation results in less impact on driving, while those that produce a more stoned or high feeling results in a greater negative effect on driving.

Development and Verification of a Linked Δ 9-THC/11-OH-THC Physiologically Based Pharmacokinetic Model in Healthy, Nonpregnant Population and Extrapolation to Pregnant Women

Conducting clinical trials to understand the exposure risk/benefit relationship of cannabis use is not always feasible. Alternatively, physiologically based pharmacokinetic (PBPK) models can be used to predict exposure of the psychoactive cannabinoid (-)-Δ⁹-tetrahydrocannabinol (THC) and its active metabolite 11-hydroxy-Δ⁹-tetrahydrocannabinol (11-OH-THC). Here, we first extrapolated in vitro mechanistic pharmacokinetic information previously quantified to build a linked THC/11-OH-THC PBPK model and verified the model with observed data after intravenous and inhalation administration of THC in a healthy, nonpregnant population. The in vitro to in vivo extrapolation of both THC and 11-OH-THC disposition was successful. The inhalation bioavailability (F_inh) of THC after inhalation was higher in chronic versus casual cannabis users (F_inh = 0.35 and 0.19, respectively). Sensitivity analysis demonstrated that 11-OH-THC but not THC exposure was sensitive to alterations in hepatic intrinsic clearance of the respective compound. Next, we extrapolated the linked THC/11-OH-THC PBPK model to pregnant women. Simulations showed that THC plasma area under the curve (AUC) does not change during pregnancy, but 11-OH-THC plasma AUC decreases by up to 41%. Using a maternal-fetal PBPK model, maternal and fetal THC serum concentrations were simulated and compared with the observed THC serum concentrations in pregnant women at term. To recapitulate the observed THC fetal serum concentrations, active placental efflux of THC needed to be invoked. In conclusion, we built and verified a linked THC/11-OH-THC PBPK model in healthy nonpregnant population and demonstrated how this mechanistic physiologic and pharmacokinetic platform can be extrapolated to a special population, such as pregnant women. SIGNIFICANCE STATEMENT: Although the pharmacokinetics of cannabinoids have been extensively studied clinically, limited mechanistic pharmacokinetic models exist. Here, we developed and verified a physiologically based pharmacokinetic (PBPK) model for (-)-Δ⁹-tetrahydrocannabinol (THC) and its active metabolite, 11-hydroxy-Δ⁹-tetrahydrocannabinol (11-OH-THC). The PBPK model was verified in healthy, nonpregnant population after intravenous and inhalation administration of THC, and then extrapolated to pregnant women. The THC/11-OH-THC PBPK model can be used to predict exposure in special populations, predict drug-drug interactions, or impact of genetic polymorphism.

Steering clear: Traffic violations among emerging adults who engage in habitual or casual cannabis use

While some research has shown that cannabis use can impair driving ability, evidence to the degree and impact of impairment are lacking. This study examined the association between habitual or casual cannabis use and past-year traffic violations among emerging adults (EAs). Data come from the 2012 Canadian Community Health Survey-Mental Health. Respondents (n = 5630) were categorized as: early (15-19 y), middle (20-24 y), and late (25-29 y) EAs. Traffic violations were measured using self-report and cannabis use was measured using the WHO Composite International Diagnostic Interview. The prevalence of traffic violations was higher for males (19.2 %) vs females (9.9 %) and middle (16.2 %) and late (19.4 %) EAs vs early (8.8 %) EAs. The odds of reporting traffic violations were higher for EAs who engaged in habitual [OR = 1.77 (1.17-2.67)] or casual [OR = 1.79 (1.27-2.51)] cannabis use when compared to non-users. Age moderated the association such that higher odds of traffic violations were reported in early EAs who were casual cannabis users and middle EAs who were habitual or casual cannabis users when compared to non-users. Use of other drugs was also a moderator-in the absence vs. presence of other drug use, odds of traffic violations were higher in those who engaged in either habitual or casual use of cannabis. When accounting for the moderating effects of age and drug use, habitual and casual cannabis use resulted in increased odds of a traffic violation. Future research is warranted to explore the robustness of our findings.

Safety and Tolerability of Cannabidiol in Parkinson Disease: An Open Label, Dose-Escalation Study

Background: Cannabis is increasingly used in Parkinson disease (PD), despite little information regarding benefits and risks. Objectives: To investigate the safety and tolerability of a range of doses of cannabidiol (CBD), a nonintoxicating component of cannabis, and it's effect on common parkinsonian symptoms. Methods: In this open-label study Coloradans with PD, substantial rest tremor, not using cannabis received plant-derived highly purified CBD (Epidiolex®; 100 mg/mL). CBD was titrated from 5 to 20-25 mg/kg/day and maintained for 10-15 days. Results: Fifteen participants enrolled, two were screen failures. All 13 participants (10 male), mean (SD) age 68.15 (6.05), with 6.1 (4.0) years of PD, reported adverse events, including diarrhea (85%), somnolence (69%), fatigue (62%), weight gain (31%), dizziness (23%), abdominal pain (23%), and headache, weight loss, nausea, anorexia, and increased appetite (each 5%). Adverse events were mostly mild; none serious. Elevated liver enzymes, mostly a cholestatic pattern, occurred in five (38.5%) participants on 20-25 mg/kg/day, only one symptomatic. Three (23%) dropped out due to intolerance. Ten (eight male) that completed the study had improvement in total and motor Movement Disorder Society Unified Parkinson Disease Rating Scale scores of 7.70 (9.39, mean decrease 17.8%, p=0.012) and 6.10 (6.64, mean decrease 24.7%, p=0.004), respectively. Nighttime sleep and emotional/behavioral dyscontrol scores also improved significantly. Conclusions: CBD, in the form of Epidiolex, may be efficacious in PD, but the relatively high dose used in this study was associated with liver enzyme elevations. Randomized controlled trials are needed to investigate various forms of cannabis in PD.

Cannabinoids and the eye

Cannabis ranks among the most commonly used psychotropic drugs worldwide. In the context of the global movement toward more widespread legalisation, there is a growing need toward developing a better understanding of the physiological and pathological effects. We provide an overview of the current evidence on the effects of cannabinoids on the eye. Of the identified cannabinoids, Δ⁹-tetrahydrocannabinol is recognized to be the primary psychotropic compound, and cannabidiol is the predominant nonpsychoactive ingredient. Despite demonstrating ocular hypotensive and neuroprotective activity, the use of cannabinoids as a treatment for glaucoma is limited by a large number of potential systemic and ophthalmic side effects. Anterior segment effects of cannabinoids are complex, with preliminary evidence showing decreased corneal endothelial density in chronic cannabinoid users. Experiments in rodents, however, have shown potential promise for the treatment of ocular surface injury via antinociceptive and antiinflammatory effects. Electroretinography studies demonstrating adverse effects on photoreceptor, bipolar, and ganglion cell function suggest links between cannabis and neuroretinal dysfunction. Neuro-ophthalmic associations include ocular motility deficits and decrements in smooth pursuit and saccadic eye movements, although potential therapeutic effects for congenital and acquired nystagmus have been observed.

Acute effects of cannabis consumption on exercise performance: a systematic and umbrella review

INTRODUCTION

The goal of this systematic and umbrella review was to regroup all systematic reviews, non-systematic reviews and all original articles into one convenient publication that would facilitate the theoretical and applied scientific investigations directed on cannabis consumption and exercise performance, to update current findings on the matters, and assess evidence quality.

EVIDENCE ACQUISITION

The systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) method. A computer-based systematic search was conducted in September 2019 through the Pubmed, Scopus and SPORTDiscus databases. The reliability of the systematic search was assured by having the article selection process entirely repeated by a second author. Strength of evidence of the selected articles was assesses using a modified version of the Downs and Black Checklist.

EVIDENCE SYNTHESIS

The systematic search yielded a total of 8 peer-reviewed publications as well as 10 literature reviews. Results show that cannabis consumption prior to exercise induces decrements in performance (reduced ability to maintain effort, physical/maximal work capacity), undesired physiological responses (increased heart and breathing rate as well as myocardial oxygen demand) and neurological effects on balance (increased sway).

CONCLUSIONS

Based on the articles included in this review, the authors conclude that cannabis consumption has an ergolytic effect on exercise performance and therefore does not act as a sport performance enhancing agent as raised by popular beliefs. Thus, cannabis consumption prior to exercise should be avoided in order to maximize performance in sports. Further research should mimic modern THC dosage (150 mg).

Pharmacodynamic dose effects of oral cannabis ingestion in healthy adults who infrequently use cannabis

BACKGROUND

Prior controlled cannabis research has mostly focused on smoked cannabis and predominantly included frequent cannabis users. Oral cannabis products ("edibles") make up a large and growing segment of the retail cannabis market. This study sought to characterize the pharmacodynamic effects of oral cannabis among infrequent cannabis users.

METHODS

Seventeen healthy adults who had not used cannabis for at least 60 days completed four experimental sessions in which they consumed a cannabis-infused brownie that contained 0, 10, 25, or 50 mg THC. Subjective effects, vital signs, cognitive/psychomotor performance, and blood THC concentrations were assessed before and for 8 h after dosing.

RESULTS

Relative to placebo, the 10 mg THC dose produced discriminable subjective drug effects and elevated heart rate but did not alter cognitive/psychomotor performance. The 25 and 50 mg THC doses elicited pronounced subjective effects and markedly impaired cognitive and psychomotor functioning compared with placebo. For all active doses, pharmacodynamic effects did not manifest until 30-60 min after ingestion, and peak effects occurred 1.5-3 h post-administration. Blood THC levels were significantly correlated with some pharmacodynamic drug effects, but were substantially lower than what is typically observed after cannabis inhalation.

CONCLUSION

Ingestion of oral cannabis dose-dependently altered subjective drug effects and impaired cognitive performance. Unlike inhaled forms of cannabis for which acute effects occur almost immediately, effects of oral cannabis were considerably delayed. In an era of legalization, education about the time course of drug effects for cannabis edibles is needed to facilitate dose titration and reduce acute overdose incidents.

MicroNIR/Chemometrics: A new analytical platform for fast and accurate detection of Δ9-Tetrahydrocannabinol (THC) in oral fluids

BACKGROUND

Δ⁹-Tetrahydrocannabinol (THC) is already considered one of the most addictive substances since an increasing number of consumers/abusers of THC and THC based products are observed worldwide. In this work, the capabilities of a novel miniaturized and portable MicroNIR spectrometer were investigated in order to propose a practical and intelligible test allowing the rapid and easy screening of Δ⁹-Tetrahydrocannabinol (THC) oral fluids without any pretreatment.

METHODS

Specimens from volunteers were collected in order to consider any sources of variability in the spectral response and spiked with increasing amount of THC in order to realize predictive models to be used in real cases. Partial Least Square-Discriminant Analysis (PLS-DA) and Partial Least Square regression (PLSr) for the simultaneously detection and quantification of THC, were applied to baseline corrected spectra pre-treated by first derivative transform.

RESULTS

Results demonstrated that MicroNIR/Chemometric platform is statistically able to identify THC abuse in simulated oral fluid samples containing THC from 10 to 100 ng/ml, with a precision and a sensitivity of about 1.51% and 0.1% respectively.

CONCLUSIONS

The coupling MicroNIR/Chemometrics permits to simplify THC abuse monitoring for roadside drug testing or workplace surveillance and provides the rapid interpretation of results, as once the model is assessed, it can be used to process real samples in a "click-on" device.

Acute Illness Associated With Cannabis Use, by Route of Exposure: An Observational Study

BACKGROUND

Little is known about the relative harms of edible and inhalable cannabis products.

OBJECTIVE

To describe and compare adult emergency department (ED) visits related to edible and inhaled cannabis exposure.

DESIGN

Chart review of ED visits between 1 January 2012 and 31 December 2016.

SETTING

A large urban academic hospital in Colorado.

PARTICIPANTS

Adults with ED visits with a cannabis-related International Classification of Diseases, Ninth or 10th Revision, Clinical Modification (ICD-9-CM or ICD-10-CM), code.

MEASUREMENTS

Patient demographic characteristics, route of exposure, dose, symptoms, length of stay, disposition, discharge diagnoses, and attribution of visit to cannabis.

RESULTS

There were 9973 visits with an ICD-9-CM or ICD-10-CM code for cannabis use. Of these, 2567 (25.7%) visits were at least partially attributable to cannabis, and 238 of those (9.3%) were related to edible cannabis. Visits attributable to inhaled cannabis were more likely to be for cannabinoid hyperemesis syndrome (18.0% vs. 8.4%), and visits attributable to edible cannabis were more likely to be due to acute psychiatric symptoms (18.0% vs. 10.9%), intoxication (48% vs. 28%), and cardiovascular symptoms (8.0% vs. 3.1%). Edible products accounted for 10.7% of cannabis-attributable visits between 2014 and 2016 but represented only 0.32% of total cannabis sales in Colorado (in kilograms of tetrahydrocannabinol) during that period.

LIMITATION

Retrospective study design, single academic center, self-reported exposure data, and limited availability of dose data.

CONCLUSION

Visits attributable to inhaled cannabis are more frequent than those attributable to edible cannabis, although the latter is associated with more acute psychiatric visits and more ED visits than expected.

PRIMARY FUNDING SOURCE

Colorado Department of Public Health and Environment.

Driving under the influence of cannabis among medical cannabis patients with chronic pain

BACKGROUND

Driving under the influence of cannabis (DUIC) is a public health concern among those using medical cannabis. Understanding behaviors contributing to DUIC can inform prevention efforts. We evaluated three past 6-month DUIC behaviors among medical cannabis users with chronic pain.

METHODS

Adults (N = 790) seeking medical cannabis certification or recertification for moderate/severe pain were recruited from February 2014 through June 2015 at Michigan medical cannabis clinics. About half of participants were male (52%) and 81% were White; their Mean age was 45.8 years. Participants completed survey measures of DUIC (driving within 2 h of use, driving while "a little high," and driving while "very high") and background factors (demographics, alcohol use, etc.). Unadjusted and adjusted logistic regressions were used to examine correlates of DUIC.

RESULTS

For the past 6 months, DUIC within 2 h of use was reported by 56.4% of the sample, DUIC while a "little high" was reported by 50.5%, and "very high" was reported by 21.1%. Greater cannabis quantity consumed and binge drinking were generally associated with DUIC behaviors. Higher pain was associated with lower likelihood of DUIC. Findings vary somewhat across DUIC measures.

CONCLUSIONS

The prevalence of DUIC is concerning, with more research needed on how to best measure DUIC. Prevention messaging for DUIC may be enhanced by addressing alcohol co-consumption.

Time to acknowledge the mixed effects of cannabis on health: a summary and critical review of the NASEM 2017 report on the health effects of cannabis and cannabinoids

This is a summary and critical review of The National Academies of Sciences, Engineering and Medicine (NASEM) report of cannabis’ health effects. The report stated that effects of cannabis are understudied and research findings are mixed. It concluded that the under developed evidence base poses a public health risk and rightly addressed complications of cannabis research that need to be collaboratively resolved. We support NASEM’s urgent call for research, but add that the mixed evidence base cannot be solely attributed to research limitations. Rather, we propose a need to acknowledge the heterogeneity in cannabis’ effects to advance the field.

Older Adults Driving Under the Influence: Associations With Marijuana Use, Marijuana Use Disorder, and Risk Perceptions

Despite increasing marijuana use among the 50+ age group, little research has been done on marijuana’s impact on older adults’ driving under the influence (DUI). Using the 2013 to 2014 National Survey on Drug Use and Health data, this study examined the association of older adults’ self-reported DUI with marijuana use, marijuana abuse/dependence, and marijuana risk perception. The findings show that one third of past-year marijuana users aged 50+ reported past-year DUI, two thirds of which involved drugs. Those with marijuana abuse/dependence were 2.6 times more likely than those without the disorder to report DUI, controlling for alcohol abuse/dependence, other illicit drug use, and sociodemographic and health/mental health statuses. As safe driving is key to prolonging independence in late life, clinicians need to educate older adults about the risk of marijuana use, alone and with other substances, on their driving capacity and provide age-appropriate treatment for marijuana use disorder.