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Background: Methylphenidate is a routinely prescribed treatment for attention-deficit/hyperactivity disorder with misuse potential owing to its perceived performance-enhancing and euphoric properties. Although clinically effective, there is limited understanding of how methylphenidate affects safety-sensitive tasks such as driving when used by healthy individuals., Aim: Explore the acute effects of 10 mg methylphenidate on driving performance and gaze behaviour., Methods: Twenty-five fully licensed, healthy adults (mean age = 33.5 ± 7.8 years, 64% male) took part in two 40-min simulated highway drives with simultaneous eye movements monitored using a proprietary automotive-grade driver monitoring system (Seeing Machines). Driving performance was assessed using the standard deviation of lateral position, standard deviation of speed and steering variability. Visual scanning efficiency was determined using ocular metrics, such as fixation duration and rate, gaze transition entropy, and stationary gaze entropy, were assessed to determine visual scanning efficiency., Results: Methylphenidate significantly improved driving performance by reducing lane weaving and speed variation, particularly in the latter half of the drive. Although a significant reduction in fixation duration was observed, all other ocular metrics remained unchanged., Conclusions: Methylphenidate mitigates performance decrements typically associated with prolonged and monotonous driving. The absence of pronounced oculomotor effects suggests that a single 10 mg dose of methylphenidate has no deleterious impact on visual scanning behaviour during driving tasks with low-to-moderate cognitive demand. Future research should investigate the effects of methylphenidate under various dosing and driving conditions to better understand its impact., Trial Registration: ACTRN12620000499987., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: ACH is supported by a Rebecca L Cooper Al and Val Rosenstrauss Fellowship (GNT: F2021894) and held an NHMRC Early Career Fellowship (GNT: 1119960). LAD received a R.D Wright Career Development Fellowship with no conflicts of interest. BA, SR, and TRA declare no conflicts of interest. BS is employed by Seeing Machines without conflicts of interest related to this publication or any financial support that could affect its outcome.

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., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: ACH is supported by a Rebecca L. Cooper Al and Val Rosenstrauss Fellowship (GNT: F2021894). All other authors declare that there is no conflict of interest.

Blood and oral fluid Δ 9 -tetrahydrocannabinol (THC) concentrations are often used to identify cannabis-impaired drivers. We used meta-analytic techniques to characterise the relationships between biomarkers of cannabis use, subjective intoxication, and impairment of driving and driving-related cognitive skills. Twenty-eight publications and 822 driving-related outcomes were reviewed. Each outcome was measured in concert with one or more biomarkers of cannabis/THC use and/or subjective intoxication. Higher blood THC and 11-OH-THC concentrations, oral fluid THC concentrations and subjective ratings of intoxication were associated with greater impairment in 'other' (mostly occasional) cannabis users (p's<0.05). Blood 11-COOH-THC concentrations were associated with impairment after inhaling, but not orally ingesting, cannabis/THC. However, these 'biomarker-performance' relationships (R) were only very weak (blood THC post-ingestion : -0.08; blood THC post-inhalation : -0.10; blood 11-OH-THC post-ingestion : -0.13), weak (blood 11-OH-THC post-inhalation : -0.24; oral fluid THC post-inhalation : -0.36; subjective intoxication: -0.29) or moderate (blood 11-COOH-THC post-inhalation : -0.43) in strength. No significant biomarker-performance relationships were observed in 'regular' (weekly or more often) cannabis users (p's>0.10), although the analyses were less robust. Blood and oral fluid THC concentrations are relatively poor indicators of cannabis/THC-induced impairment., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

As the use of cannabis for medical purposes becomes increasingly prevalent, driving under the influence of cannabis (DUIC) is emerging as a major public health issue. Understanding current behaviours, attitudes and perceptions around DUIC in medical cannabis users is an important first step in addressing this issue. Here we present the results from the driving-related subsection of the Cannabis as Medicine 2018-2019 Survey (CAMS18) of current Australian medical cannabis users (n = 1388). Of the 806 respondents who reported driving a motor vehicle in the last month, 34.6% said they typically drive within 3 hours of cannabis use, thereby risking DUIC, while more than 50% waited at least 7 hours before driving. A majority of respondents thought that their medical cannabis use did not affect their driving ability, and most denied any specific effects of cannabis on speeding, risk taking, reaction time, attentiveness or lane departures. A substantial majority (70.9%) felt confident in accurately assessing their own driving ability after using medical cannabis. Binary logistic regression showed that frequency of use and confidence to assess driving ability were strongly related to DUIC behaviour (i.e. driving soon after cannabis use). These results suggest a relatively high prevalence of DUIC and low perception of risk among this sample of medical cannabis users. Further research is needed to better understand the acute and chronic effects of medical cannabis use on driving and the relation between perceived and actual driving ability., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objective: Interest in the use of cannabidiol (CBD) is increasing worldwide as its therapeutic effects are established and legal restrictions moderated. Unlike Δ 9 -tetrahydrocannabinol (Δ 9 -THC), CBD does not appear to cause cognitive or psychomotor impairment. However, further assessment of its effects on cognitively demanding day-to-day activities, such as driving, is warranted. Here, we describe a study investigating the effects of CBD on simulated driving and cognitive performance., Methods: Thirty healthy individuals will be recruited to participate in this randomised, double-blind, placebo-controlled crossover trial. Participants will complete four research sessions each involving two 30-min simulated driving performance tests completed 45 and 210 min following oral ingestion of placebo or 15, 300, or 1,500 mg CBD. Cognitive function and subjective drug effects will be measured, and blood and oral fluid sampled, at regular intervals. Oral fluid drug testing will be performed using the Securetec DrugWipe® 5S and Dräger DrugTest® 5000 devices to determine whether CBD increases the risk of "false-positive" roadside tests to Δ 9 -THC. Noninferiority analyses will test the hypothesis that CBD is no more impairing than placebo., Conclusion: This study will clarify the risks involved in driving following CBD use and assist in ensuring the safe use of CBD by drivers., (© 2020 John Wiley & Sons Ltd.)

Background: The main psychoactive component of cannabis, delta-9-tetrahydrocannabinol (THC), can impair driving performance. Cannabidiol (CBD), a non-intoxicating cannabis component, is thought to mitigate certain adverse effects of THC. It is possible then that cannabis containing equivalent CBD and THC will differentially affect driving and cognition relative to THC-dominant cannabis., Aims: The present study investigated and compared the effects of THC-dominant and THC/CBD equivalent cannabis on simulated driving and cognitive performance., Methods: In a randomized, double-blind, within-subjects crossover design, healthy volunteers (n = 14) with a history of light cannabis use attended three outpatient experimental test sessions in which simulated driving and cognitive performance were assessed at two timepoints (20-60 min and 200-240 min) following vaporization of 125 mg THC-dominant (11% THC; < 1% CBD), THC/CBD equivalent (11% THC, 11% CBD), or placebo (< 1% THC/CBD) cannabis., Results/outcomes: Both active cannabis types increased lane weaving during a car-following task but had little effect on other driving performance measures. Active cannabis types impaired performance on the Digit Symbol Substitution Task (DSST), Divided Attention Task (DAT) and Paced Auditory Serial Addition Task (PASAT) with impairment on the latter two tasks worse with THC/CBD equivalent cannabis. Subjective drug effects (e.g., "stoned") and confidence in driving ability did not vary with CBD content. Peak plasma THC concentrations were higher following THC/CBD equivalent cannabis relative to THC-dominant cannabis, suggesting a possible pharmacokinetic interaction., Conclusions/interpretation: Cannabis containing equivalent concentrations of CBD and THC appears no less impairing than THC-dominant cannabis, and in some circumstances, CBD may actually exacerbate THC-induced impairment.