The effects of cannabis and alcohol on driving performance and driver behaviour: a systematic review and meta-analysis

Alcohol and Drug Testing in Motor Vehicle Crashes

Alcohol-impairment is a leading cause of motor vehicle crash injuries and fatalities. It has also come to light in recent years that driving under the influence of drugs is becoming more and more prevalent and also contributes to motor vehicle crash injuries and fatalities. This review describes the effects of alcohol and commonly used drugs (hallucinogens,stimulants, etc) on driving capabilities, and the matrices and tests used to detect these analytes in motor vehicle drivers, pedestrians, and motorcycle drivers.

"Stoned on the road": A systematic review of cannabis-impaired driving educational initiatives targeting young drivers in Canada

BACKGROUND

With recreational cannabis legalized across Canada, concerns persist about youth driving under the influence of cannabis (DUIC). However, the extent of DUIC education and prevention efforts aimed at young Canadians remains unclear. This systematic review examines recent Canadian initiatives (2017 onwards) focused on reducing DUIC among youth. Specifically, we investigate (1) the types of initiatives and target audiences, (2) content and delivery methods, (3) sustainability, and (4) evidence of impact.

METHODS

A comprehensive search was conducted across MEDLINE, PsycINFO, CINAHL, SCOPUS, and EMBASE (January 1, 2017-July 10, 2023), along with various grey literature sources. Initiatives were included if they targeted DUIC behaviour among youth aged 16 to 24, were developed and delivered in Canada by reputable organizations or individuals with institutional support, and aimed to address DUIC behaviour or its enabling conditions. Data extraction and quality appraisal were performed.

RESULTS

Fifteen Canadian initiatives were identified: seven educational programs and eight awareness campaigns, encompassing national and regional levels. Delivery methods included in-person workshops, digital tools, online programs, and smartphone applications. While some initiatives increased awareness and influenced perceptions of DUIC, evidence of behaviour change remained limited. Challenges related to sustainability, particularly concerning long-term funding and digital platform maintenance, were noted.

CONCLUSIONS

This research highlights the progress made in addressing youth DUIC in Canada. Examining current DUIC educational initiatives is crucial for refining strategies, shaping policy, and allocating resources to prioritize the safety of young Canadians. Future efforts should focus on assessing behavioural impacts and ensuring financial sustainability and program longevity.

Substitution and Complementarity in the Consumption of Alcohol, Cannabis, and Opium

Understanding the behavior of populations of drug consumers has been and remains a topic of keen interest. Using a unique dataset on 25 districts from Bengal, India, from 1911 to 1925, we analyze whether populations of consumers treat alcohol, cannabis, and opium as economic substitutes or complements in a legal regime. Additionally, we examine responsiveness to prices and income. Our analysis has three main findings. First, we find evidence of substitution between alcohol and cannabis bud. Second, cannabis leaf is a complement for alcohol but a substitute for cannabis bud. Third, we find negative income elasticity for alcohol, cannabis bud, and opium consumption. These findings on the link between consumption patterns and economic factors can guide harm reduction strategies.

Perceptions and patterns of Cannabis use in emergency department patients following recreational legalization in Massachusetts

INTRODUCTION

In Massachusetts, cannabis was legalized for recreational use in 2016. Legalization was associated with an increase in cannabis-related emergency department (ED) visits. The purpose of this study was to characterize cannabis use in an ED population in Massachusetts following legalization.

METHODS

This was a convenience sample survey study conducted at an academic medical center ED in Massachusetts. Patients aged 18 or older reporting cannabis use within the last month were eligible. Participants were surveyed about cannabis use including: use patterns, risks and benefits, concomitant substance use, and changes in use post-legalization. Patients and treating physicians were asked whether ED visits were attributable to cannabis to determine discordance. Data analysis used descriptive statistics.

RESULTS

Between July 2019 and May 2021, 200 patients were enrolled. Relaxation and analgesia were the most common reported benefits of cannabis. 46 % of patients prescribed an opioid reported decreased opioid use due to cannabis. 31 % reported no perceived risks from cannabis, and 22 % believed cannabis impaired driving. Twenty-one patients presented with a cannabis-related chief complaint per the treating physician; 11 (52.4 %) believed their presentation was due to cannabis. Post-legalization, 28.5 % of patients reported increased cannabis use.

CONCLUSION

In this study of patients with cannabis use presenting to a Massachusetts ED, the majority did not report increased use following recreational legalization. Patients reported multiple benefits of cannabis, including decreased opioid use, but minimized risks including intoxicated driving. Almost half of patients with cannabis-related symptoms did not attribute them to cannabis. These findings may inform harm-reduction strategies.

Reliability of roadside oral fluid testing devices for ∆9-tetrahydrocannabinol (∆9-THC) detection

Driving under the influence of cannabis (DUIC) is increasing worldwide, and cannabis is the most prevalent drug after alcohol in impaired driving cases, emphasizing the need for a reliable traffic enforcement strategy. ∆9-tetrahydrocannabinol (THC) detection in oral fluid has great potential for identifying recent cannabis use; however, additional data are needed on the sensitivities, specificities, and efficiencies of different oral fluid devices for detecting cannabinoids at the roadside by police during routine traffic safety enforcement efforts. At the roadside, 8945 oral fluid THC screening tests were performed with four devices: AquilaScan®, Dräger DrugTest®, WipeAlyser Reader®, and Druglizer®. A total of 530 samples screened positive for THC (5.9%) and were analyzed by liquid chromatography-tandem mass spectrometry at multiple cutoff concentrations (2 ng/mL, 10 ng/mL, and manufacturers' recommended device cutoffs) to investigate device performance. Results varied substantially, with sensitivities of 0%-96.8%, specificities of 89.8%-98.5%, and efficiencies of 84.3%-97.8%. The Dräger DrugTest® outperformed the other devices with a 96.8% sensitivity, 97.1% specificity, and 97.0% efficiency at a 5-ng/mL LC-MS/MS confirmation cutoff. The WipeAlyser Reader® had good performance with a 91.4% sensitivity, 97.2% specificity, and 96.4% efficiency. AquilaScan® and Druglizer® had unacceptable performance for cannabinoid detection, highlighted by sensitivity <13%. The choice of roadside oral fluid testing device must offer good analytical performance for cannabinoids because of its high prevalence of use and impact on road safety.

Young adult impaired driving behaviors and perceived norms of driving under the influence of simultaneous alcohol and cannabis use

BACKGROUND

Impaired driving behaviors among young adults who are under the influence of simultaneous alcohol and marijuana/cannabis (SAM) use are associated with increased risks of motor vehicle accidents and resulting increased injury and mortality. Exploration of associations with descriptive and injunctive norms may have prevention implications.

METHODS

Young adults (aged 18-25; N = 1941) in the 2019 cohort of the Washington Young Adult Health Survey comprised study participants. Associations between descriptive norms (estimates of other's frequency of driving under the influence of SAM [DUI-SAM] and riding with a SAM impaired driver [RWI-SAM]), injunctive norms (perceived approval or disapproval of DUI-SAM and RWI-SAM for young adults in their community), and past month DUI and RWI behaviors were assessed with logistic regression models, adjusting for covariates and applying post-stratification weights.

RESULTS

DUI-SAM was reported by 2.7% and almost double (5.3%) reported RWI-SAM at least once in the past month. Almost half of the participants believed the average young adults in Washington State engaged in DUI-SAM (49.8%) and RWI-SAM (48.7%) at least once a month in the past year (i.e., descriptive norms). The majority reported DUI-SAM (68.8%) and RWI-SAM (67.6%) to be totally unacceptable for young adults in their community (i.e., injunctive norms). In models adjusting for covariates including SAM use frequency and corresponding injunctive norms, descriptive norms were not associated with DUI, but were positively associated with RWI-SAM. However, after controlling for SAM use frequency and descriptive norms, higher perceived approval (i.e., injunctive norms) was significantly associated with increased odds of all DUI and RWI behaviors.

CONCLUSIONS

Injunctive norms for SAM impaired driving behaviors may be a promising intervention focus for DUI and RWI behaviors. Future research is needed to replicate these findings to determine if development and evaluation of individual and community-based interventions focused on changing normative beliefs are warranted.

Evaluating risks, monitoring cannabis use, and planning to get home safely: Exploring self-regulation processes associated with cannabis use and driving

OBJECTIVE

Preventing Cannabis-impaired driving involves understanding how users assess risk, monitor their use, and plan to get home safely. While extant research has shown substantial heterogeneity in patterns of cannabis use among different user groups, far less research has examined self-regulation among users. The current study aims to identify sub-groups of individuals who used or have used cannabis based on how they perceive risks, monitor their impairment, and plan to avoid driving under the influence of cannabis (DUIC) to examine how the different profiles relate to DUIC outcomes.

METHODS

Participants were a Canadian sub-sample in the province of British Columbia who participated in the 2022 International Cannabis Policy study and reported ever using or currently using cannabis (N = 886, Mage = 43.58, SDage = 13.67; 63% female). Risk perception, impairment monitoring, planning ability, DUIC-related behaviors, Cannabis use and related problems were assessed through an online self-reported survey.

RESULTS

Latent profile analysis identified three groups of self-regulators based on their level of risk perception, monitoring, and plan to avoid DUI. The majority (51%) of participants showed moderate self-regulation with average levels of risk perception, monitoring, and planning. A "highly self-regulated" group (20%) had the highest risk perception, monitoring, and planning. A "low self-regulated" group (29%) had the lowest risk perception, less confidence in monitoring, and lower DUI planning. There were significant differences between the profiles and DUIC outcomes. Cannabis users (including both historical and current users) with high self-regulation were less likely to be passengers of drivers under the influence and more likely to intervene to stop friends from driving while impaired, compared to those with low or moderate self-regulation. However, there were no profile differences in reports of having ever driven under the influence of cannabis.

CONCLUSIONS

Differences in risk perception, monitoring, and planning are associated with self-regulatory abilities. Understanding diverse self-regulation patterns among people who have used cannabis can help identify and mitigate risky behaviors, including DUI.

Attitudes toward driving after cannabis use: a systematic review

BACKGROUND

Driving after cannabis use (DACU) is associated with increased risk of motor vehicle collisions. As cannabis legalization expands, DACU is emerging as a major public safety concern. Attitudes have a significant impact on behavioural decision making. As such, understanding the degree to which people have favorable or unfavorable evaluations of DACU is an important first step for informing prevention efforts. This systematic review summarizes existing evidence on attitudes toward DACU, their association with actual or intended DACU, and changes in attitudes following legalization of recreational cannabis.

METHODS

Four electronic databases (MEDLINE, EMBASE, PsycINFO, and TRID) were searched for studies that reported attitudes or changes in attitudes toward DACU published between their inception dates and February 26 2024. A total of 1,099 records were retrieved. Studies were analyzed using an inductive thematic synthesis approach.

RESULTS

Seventy studies from seven countries originating predominantly from the United States and Canada met inclusion criteria. Thematic analysis identified six themes. (I) Attitudes toward the safety and acceptability of DACU are mixed; participants in 35 studies predominantly expressed negative attitudes toward DACU (e.g., DACU is dangerous, affects driving ability, and increases crash risk). However, 20 studies reported opposing views. (II) Attitudes toward DACU vary by age, sex/gender, and cannabis use frequency; youth, men, and frequent cannabis users tended to view DACU more favorably than older participants, women, and occasional or non-users. (III) Attitudes toward DACU are associated with past DACU and intention to DACU. (IV) DACU is viewed more favorably than driving after drinking alcohol. (V) The relationship between legal status of recreational cannabis and attitudes toward DACU is unclear. (VI) Perceived risk of apprehension for DACU is low to moderate.

CONCLUSIONS

This review found that perceptions of DACU are primarily negative but mixed. Findings suggest that attitudes toward DACU are important targets for interventions to reduce this behaviour.

A qualitative study on apparent and latent contributing factors to driving errors in Iran

Road traffic crashes (RTCs) disproportionately impact low and middle-income countries (LMICs). Current interventions in LMICs primarily target road user behavior, neglecting systemic issues and casting drivers as mere contributors. Given Iran's unique cultural, financial, and social intricacies, this study aims to explore the latent causes of RTCs, prioritizing drivers' experiences and encompassing insights from various traffic system components. Applying a qualitative approach, data were collected through 46 semi-structured interviews with 38 participants, including drivers and experts from traffic-related organizations. Content analysis identified ten themes as contributing to driving errors. Direct factors included fatigue influenced by economic and occupational conditions, distraction from internal and external sources, reckless behaviors influenced by traffic culture and environment, and Inadequate driving skills due to training. Macro-scale challenges in road infrastructure, vehicle quality, education, and accident investigations were highlighted. The lack of a centralized traffic safety authority and a predominant focus on penalizing drivers overshadowed systemic issues. The study offers valuable insights into the complex interplay of factors contributing to driving errors in LMICs, advocating for a paradigm shift towards holistic, systemic interventions beyond individual driver behavior and challenging the conventional blame-centric view associated with driving errors.

Road hazard: a systematic review of traffic injuries following recreational cannabis legalization

PURPOSE

Acute cannabis use is associated with impaired driving performance and increased risk of motor vehicle crashes. Following the Canadian Cannabis Act's implementation, it is essential to understand how recreational cannabis legalization impacts traffic injuries, with a particular emphasis on Canadian emergency departments. This study aims to assess the impact of recreational cannabis legalization on traffic-related emergency department visits and hospitalizations in the broader context of North America.

METHODS

A systematic review was conducted according to best practices and reported using PRISMA 2020 guidelines. The protocol was registered on July 5, 2022 (PROSPERO CRD42022342126). MEDLINE(R) ALL (OvidSP), Embase (OvidSP), CINAHL (EBSCOHost), and Scopus were searched without language or date restrictions up to October 12, 2023. Studies were included if they examined cannabis-related traffic-injury emergency department visits and hospitalizations before and after recreational cannabis legalization. The risk of bias was assessed. Meta-analysis was not possible due to heterogeneity.

RESULTS

Seven studies were eligible for the analysis. All studies were conducted between 2019 and 2023 in Canada and the United States. We found mixed results regarding the impact of recreational cannabis legalization on emergency department visits for traffic injuries. Four of the studies included reported increases in traffic injuries after legalization, while the remaining three studies found no significant change. There was a moderate overall risk of bias among the studies included.

CONCLUSIONS

This systematic review highlights the complexity of assessing the impact of recreational cannabis legalization on traffic injuries. Our findings show a varied impact on emergency department visits and hospitalizations across North America. This underlines the importance of Canadian emergency physicians staying informed about regional cannabis policies. Training on identifying and treating cannabis-related impairments should be incorporated into standard protocols to enhance response effectiveness and patient safety in light of evolving cannabis legislation.

Cannabinoids detected in exhaled breath condensate after cannabis use

Cannabinoids can be detected in breath after cannabis use, but different breath matrices need to be explored as studies to date with filter-based devices that collect breath aerosols have not demonstrated that breath-based measurements can reliably identify recent cannabis use. Exhaled breath condensate (EBC) is an unexplored aqueous breath matrix that contains condensed volatile compounds and water vapor in addition to aerosols. EBC was collected from participants both before and at two time points (0.7 ± 0.2 h and 1.7 ± 0.3 h) after observed cannabis use. Eleven different cannabinoids were monitored with liquid chromatography tandem mass spectrometry. Five different cannabinoids, including Δ9-tetrahydrocannabinol (THC), were detected in EBC collected from cannabis users. THC was detected in some EBC samples before cannabis use, despite the requested abstinence period. THC was detected in all EBC samples collected at 0.7 h post use and decreased for all participants at 1.7 h. Non-THC cannabinoids were only detected after cannabis use. THC concentrations in EBC samples collected at 0.7 h showed no trend with sample metrics like mass or number of breaths. EBC sampling devices deserve further investigation with respect to modes of cannabis use (e.g, edibles), post use time points, and optimization of cannabinoid recovery.

Young Adult Alcohol and Cannabis Impaired Driving After the Opening of Cannabis Retail Stores in Washington State

Motor vehicle crashes are a leading cause of death for young adults (YA) in the USA, and driving under the influence of alcohol (DUIA), cannabis (DUIC), and simultaneous use of both substances (DUIAC) are prominent risk factors. Trends in YA impaired driving behaviors after opening of cannabis retail stores have been understudied. We examined YA trends in DUIA, DUIC, and DUIAC from immediately prior through 5 years following the opening of cannabis retail outlets in Washington State (2014-2019). Differences in trends were assessed across age, sex, and urbanicity. Weighted logistic regressions assessed yearly change in prevalence of DUIA, DUIC, and DUIAC from 2014 to 2019, using annual statewide data from the Washington Young Adult Health Survey (n = 12,963; ages 18-25). Moderation of trends by age, sex, and urbanicity was assessed. Prevalence of DUIA decreased overall (AOR = 0.93, 95% CI 0.90, 0.97) and among drinkers (AOR = 0.95, 95% CI 0.91, 0.99) but remained at concerning levels in 2019 (10% overall; 16% among drinkers). Overall DUIC did not change significantly (AOR = 0.99, 95% CI 0.96, 1.03; 11% by 2019) but decreased among those who used cannabis (AOR = 0.91, 95% CI 0.86, 0.96; 33% by 2019). DUIAC decreased but not significantly (overall: AOR = 0.89, 95% CI 0.78, 1.01; those who used alcohol and cannabis: AOR = 0.84, 95% CI 0.74, 1.04). Prevalence of YA DUI remained concerning. Trends may reflect some success in reducing DUI, but additional detection and prevention are needed.

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.

Complexity of Translating Analytics to Recent Cannabis Use and Impairment

While current analytical methodologies can readily identify cannabis use, definitively establishing recent use within the impairment window has proven to be far more complex, requiring a new approach. Recent studies have shown no direct relationship between impairment and Δ9-tetra-hydrocannabinol (Δ9-THC) concentrations in blood or saliva, making legal "per se" Δ9-THC limits scientifically unjustified. Current methods that focus on Δ9-THC and/or metabolite concentrations in blood, saliva, urine, or exhaled breath can lead to false-positive results for recent use due to the persistence of Δ9-THC well outside of the typical 3-4 h window of potential impairment following cannabis inhalation. There is also the issue of impairment due to other intoxicating substances-just because a subject exhibits signs of impairment and cannabis use is detected does not rule out the involvement of other drugs. Compounding the matter is the increasing popularity of hemp-derived cannabidiol (CBD) products following passage of the 2018 Farm Bill, which legalized industrial hemp in the United States. Many of these products contain varying levels of Δ9-THC, which can lead to false-positive tests for cannabis use. Furthermore, hemp-derived CBD is used to synthesize Δ8-THC, which possesses psychoactive properties similar to Δ9-THC and is surrounded by legal controversy. For accuracy, analytical methods must be able to distinguish the various THC isomers, which have identical masses and exhibit immunological cross-reactivity. A new testing approach has been developed based on exhaled breath and blood sampling that incorporates kinetic changes and the presence of key cannabinoids to detect recent cannabis use within the impairment window without the false-positive results seen with other methods. The complexity of determining recent cannabis use that may lead to impairment demands such a comprehensive method so that irresponsible users can be accurately detected without falsely accusing responsible users who may unjustly suffer harsh, life-changing consequences.

The association between single and dual use of cannabis and alcohol and driving under the influence and riding with an impaired driver in a large sample of Canadian adolescents

OBJECTIVE

Dual use of cannabis and alcohol has increased in adolescents, but limited research has examined how it relates to impaired driving or riding with an impaired driver (IDR) compared to single substance use. This study aimed to examine the odds of alcohol- and/or cannabis-IDR among adolescents based on their use of alcohol and/or cannabis, and whether associations differed by gender and age.

METHODS

Cross-sectional survey data were used from a sample of 69,621 students attending 182 Canadian secondary schools in the 2021/22 school year. Multilevel logistic regression estimated the odds of exclusive alcohol-IDR, exclusive cannabis-IDR, and both alcohol and cannabis IDR (alcohol-cannabis-IDR). Substance use interactions with gender and age were tested.

RESULTS

Overall, 14.7% of participants reported IDR; 7.5% reported exclusive alcohol-IDR, 3.2% reported exclusive cannabis-IDR, 4.0% reported alcohol-cannabis-IDR, and 7.4% were unsure if they had experienced IDR. The prevalence of IDR varied across substance use groups, 8.0% among nonuse, 21.9% among alcohol-only use, 35.9% among cannabis-only use, and 49.6% among dual use groups. Gender diverse, older, and students with lower socioeconomic status exhibited a higher likelihood of reporting alcohol-cannabis-IDR. Dual use was significantly associated with 9.5 times higher odds of alcohol-cannabis-IDR compared to alcohol-only use, and 3.0 times higher odds compared to cannabis-only use. Dual use was also associated with an increased likelihood of either alcohol- or cannabis-IDR.

CONCLUSIONS

This study highlights that all students, regardless of substance use, are at risk of IDR, but students engaged in dual use of alcohol and cannabis face an elevated risk compared to both peers who do not use substances and those who use only a single substance. These findings emphasize the importance of targeted interventions that address the risks associated with IDR.

Driving after substance use in Rhode Island adolescents: A cross-sectional analysis of surveillance data

OBJECTIVE

Existing literature on driving under the influence during adolescence is sparse, especially for driving after the use of non-medical prescription drugs (DAP). This study examines the prevalence of driving after use of alcohol (DAA), cannabis (DAC), and DAP, and examines the role of several potential risk and protective factors.

METHODS

This was a secondary analysis of the 2022 Rhode Island Study Survey, a cross-sectional survey of middle and high school students. Separate multivariable regressions were conducted for each outcome among lifetime users for each substance, controlling for current substance use, individual-, perceived parental-, and perceived friend-substance use risk perception, age, sexual/gender minority (SGM) status, race, ethnicity, school level, and town poverty level.

RESULTS

Among lifetime users of alcohol (n = 3849), cannabis (n = 2289), and non-medical prescription drugs (n = 611), the prevalence of DAA, DAC, and DAP was 4.9, 14.3, and 16.9%, respectively. Current substance use, high individual risk perception, being nonwhite, and being Hispanic were risk factors for DAA while perceiving parent's risk perception as negative and being heterosexual cisgender-female were protective. Current substance use, negative individual risk perception, and being nonwhite were risk factors for DAC while perceiving parent's risk perception as negative and being in high school were protective. Current substance use and older age were risk factors for DAP while perceiving parent's risk perception as negative and perceiving friend's risk perception as negative were protective.

CONCLUSIONS

Driving under the influence is a concern among adolescent substance users. Current substance use and perceived parental risk perception as negative are common risks and protective factors, respectively. Findings suggest substance-specific, heterogeneous interventions are needed. For example, interventions focusing on peer perceptions are most relevant for DAP, while shifting personal perceptions of harm are most relevant for DAC.

Risk factors associated with driving after marijuana use among West Virginia college students during the COVID-19 pandemic

OBJECTIVES

The purpose of this study was to assess sociodemographic and behavioral risk factors associated with driving after marijuana use (DAMU) among West Virginia college students.

METHODS

Participants were recruited from West Virginia University between September and November 2022. The study sample was restricted to students who were ≥18 years of age; reported recently driving; possessed a current, valid driver's license from any US state; and were enrolled for at least one credit hour in the Fall 2022 semester.

RESULTS

Among respondents (N = 772), 28.9% reported DAMU. Students who had a GPA of B (adjusted odds ratio [AOR]: 2.17, 95% confidence interval [CI]: 1.06-4.42), smoked or ingested marijuana in the past year (AOR: 26.51, 95% CI: 10.27-68.39), drove after drinking (AOR: 2.38, 95% CI: 1.18-4.79), and used both marijuana and alcohol concurrently and then drove (AOR: 10.39, 95% CI: 2.32-46.54) associated with DAMU. Individuals who felt the behavior was somewhat dangerous or not dangerous or thought their peers approved of DAMU showed significant associations with DAMU.

CONCLUSIONS

As DAMU was prevalent, future interventions that raise awareness of the danger and potential consequences of DAMU may be needed to reduce this risky behavior on college campuses.

Risk of motor vehicle collision associated with cannabis and alcohol use among patients presenting for emergency care

BACKGROUND

The objective of this study was to examine the relationship between cannabis and alcohol use and occurrence of motor vehicle collision (MVC) among patients in the emergency department (ED).

METHODS

This was a cross-sectional study of visits to EDs in Denver, CO, Portland, OR, and Sacramento, CA by drivers who were involved in MVCs and presented with injuries (cases) and non-injured drivers (controls) who presented for medical care. We obtained blood samples and measured delta-9-THC and its metabolites. Alcohol levels were determined by breathalyzer or samples taken in the course of clinical care. Participants completed a research-assistant-administered interview consisting of questions about drug and alcohol use prior to their visit, context of use, and past-year drug and alcohol use. Multiple logistic regression was used to estimate the association between MVC and cannabis/alcohol use, adjusted for demographic characteristics. We then stratified participants based on levels of cannabis use and calculated the odds of MVC across these levels, first using self-report and then using blood levels for delta-9-THC in separate models. We conducted a case-crossover analysis, using 7-day look-back data to allow each participant to serve as their own control. Sensitivity analyses examined the influence of usual use patterns and driving in a closed (car, truck, van) versus open (motorcycle, motorbike, all-terrain vehicle) vehicle.

RESULTS

Cannabis alone was not associated with higher odds of MVC, while acute alcohol use alone, and combined use of alcohol and cannabis were both independently associated with higher odds of MVC. Stratifying by level of self-reported or measured cannabis use, higher levels were not associated with higher odds for MVC, with or without co-use of alcohol; in fact, high self-reported acute cannabis use was associated with lower odds of MVC (odds ratio [OR] 0.18, 95% confidence interval [CI] 0.05-0.65). In the case-crossover analysis, alcohol use alone or in combination with cannabis was associated with higher odds of MVC, while cannabis use alone was again associated with decreased odds of MVC.

CONCLUSIONS

Alcohol use alone or in conjunction with cannabis was consistently associated with higer odds for MVC. However, the relationship between measured levels of cannabis and MVC was not as clear. Emphasis on actual driving behaviors and clinical signs of intoxication to determine driving under the influence has the strongest rationale.

The theory of planned behavior and alcohol protective behavioral strategies: a prospective study examining the role of habit and gender invariance

OBJECTIVES

Alcohol Protective Behavioral Strategies (PBS) have consistently shown to be effective in reducing alcohol use and its associated consequences. We aimed to examine the explanatory value of the Theory of Planned Behavior (TPB) for using five PBS, studying the role of habit, and its potential variation across genders.

METHODS

Targeted sampling was used to recruit 339 young adults in the community (women = 50.7%; mean age = 2.21[SD = 2.21]), who completed baseline and 2-month follow-up questionnaires.

RESULTS

The explained variance of the TPB ranged from 58-68% for intention to use PBS, and 18-50% for behavior. The inclusion of habit produced increases of 17-26% in explained variance in intention, while explained variance in behavior remained similar. Habit was the strongest predictor of intention to use PBS, followed by attitude. Except for one behavior (drinking slowly), habits did not moderate the intention-behavior relationship, and the explanatory value of the TPB did not differ across genders.

CONCLUSIONS

Our findings support the utility of the TPB as an explanatory model of alcohol PBS, along with the need to include habits within the framework of dual-process models. Interventions aimed at promoting alcohol PBS could be optimized by targeting attitudes towards PBS and habits.

Cannabis Is Not Doping

The World Anti-Doping Agency (WADA) classifies cannabis, all phytocannabinoids, and synthetics as doping, except for CBD. For agency, a method for doping substance must meet two criteria: performance enhancement (ergogenicity), health risk, or violation of the spirit of sports. Cannabis is neither ergogenic nor ergolytic (performance worsens), and the health risks for athletes are overestimated after 20 years of research. The significant problem remains in the complex (and difficult interpretation) definition of the spirit of sports, which transcends the objectives of sports excellence (performance and injury prevention) for moral policing. This perspective presents an evidence-based counterargument recommending the removal of cannabis and phytocannabinoids from the WADA Prohibited List.

Can inhaled cannabis users accurately evaluate impaired driving ability? A randomized controlled trial

Aims

To study the effect of inhaled cannabis on self-assessed predicted driving ability and its relation to reaction times and driving ability on a driving simulator.

Participants and methods

30 healthy male volunteers aged 18-34: 15 chronic (1-2 joints /day) and 15 occasional (1-2 joints/week) consumers. Self-assessed driving confidence (visual analog scale), vigilance (Karolinska), reaction time (mean reciprocal reaction time mRRT, psychomotor vigilance test), driving ability (standard deviation of lane position SDLP on a York driving simulator) and blood concentrations of delta-9-tétrahydrocannabinol (THC) were measured before and repeatedly after controlled inhalation of placebo, 10 mg or 30 mg of THC mixed with tobacco in a cigarette.

Results

Cannabis consumption (at 10 and 30 mg) led to a marked decrease in driving confidence over the first 2 h which remained below baseline at 8 h. Driving confidence was related to THC dose and to THC concentrations in the effective compartment with a low concentration of 0.11 ng/ml for the EC50 and a rapid onset of action (T1/2 37 min). Driving ability and reaction times were reduced by cannabis consumption. Driving confidence was shown to be related to driving ability and reaction times in both chronic and occasional consumers.

Conclusions

Cannabis consumption leads to a rapid reduction in driving confidence which is related to reduced ability on a driving simulator.

Clinical trial registration

ClinicalTrials.gov, identifier: NCT02061020.

Incremental Predictive Validity of the Dualistic Model of Passion for Cannabis Use Among College Undergraduate Students With and Without a Cannabis Use Disorder

Introduction

We examined whether the Dualistic Model of Passion (DMP; i.e., obsessive passion [OP] and harmonious passion [HP]) for cannabis use was prospectively associated with cannabis use and use-related outcomes, and with academic performance, relationship attachment style, and social connectedness among college students. We also explored whether the DMP was associated with outcomes when included in a model using established constructs (e.g., coping motives, refusal self-efficacy, cannabis use disorder [CUD] symptoms) as predictors of cannabis use and outcomes.

Methods

Using a longitudinal cohort design (baseline, 5-month, 10-month [timepoints chosen to better correspond to 9-month academic year]), 513 undergraduate students from two universities who reported using cannabis at least four times in the past month completed a baseline survey (308 meeting criteria for CUD). We used Generalized Estimating Equations to assess longitudinal associations between OP/HP and cannabis use and academic/social outcomes at 5-month and 10-month.

Results

At baseline, participants were young adults (Mean age = 20.57, SD = 2.51), 78.8% non-Hispanic, 83.8% White, 55.0% female, and 72.3% heterosexual. Greater HP was not associated with greater past month cannabis use or cannabis-related problems. Greater OP was associated with greater past month cannabis use and more cannabis-related problems. There were no significant passion by time interactions. Greater HP was associated with more anxious attachment. OP was associated with less social connection.

Conclusion

This research suggests that the DMP provides novel information about factors associated with cannabis use and use-related consequences, which can aid in our understanding of cannabis use, misuse, and CUD among college students.

Injunctive Norms and Driving Under the Influence and Riding With an Impaired Driver Among Young Adults in Washington State

PURPOSE

Alcohol- and cannabis-impaired driving behaviors remain a public health concern especially among young adults (i.e., ages 18-25). Limited updates to prevention efforts for these behaviors may be due, in part, to limited understanding of malleable psychosocial predictors. The current study assessed associations between perceived injunctive norms (i.e., acceptability) of driving under the influence of alcohol (DUI-A) and cannabis (DUI-C), and riding with a driver under the influence of alcohol (RWI-A) and cannabis (RWI-C) in Washington State young adults.

METHODS

Participants included 1,941 young adults from the 2019 cohort of the Washington Young Adult Health Survey. Weighted logistic regressions assessed the associations between peer injunctive norms and impaired driving-related behaviors.

RESULTS

A weighted total of 11.5% reported DUI-A, 12.4% DUI-C, 10.9% RWI-A, and 20.9% RWI-C at least once in the past 30 days. Overlap between the outcomes was observed, indicating some young adults had engaged in multiple impaired driving-related behaviors. After controlling for substance use frequency, weighted logistic regressions indicated more positive perceived injunctive norms were associated with nearly 2 ½ times higher odds of DUI-A, 8 times higher odds of DUI-C, 4 times higher odds of RWI-A and six and a half times higher odds of RWI-C.

DISCUSSION

Results increase the understanding of how injunctive norms-a potentially malleable psychosocial factor-are associated with four impaired driving-related outcomes. Prevention programs that focus on assessing and addressing the norms of these outcomes individually and collectively, such as normative feedback interventions and media campaigns, may be helpful in reducing these behaviors.

Collisions and cannabis: Measuring the effect of recreational marijuana legalization on traffic crashes in Washington State

OBJECTIVE

Washington State was among the first states in the US to legalize recreational consumption and retail sales of marijuana. Recreational use of cannabis was legalized December 6, 2012, following the passage of Initiative 502 30 days prior. Roughly 19 months later the first retail cannabis stores opened their doors for public sales ("commercialization"). I measure the impact of cannabis legalization and commercialization on traffic collisions in Washington State.

METHODS

With county-level vehicle crash data from the Washington State Department of Transportation collected monthly, I utilize an interrupted time-series framework with Poisson estimation to compare traffic collisions with recreational retail cannabis sales revenue from 2011 (three years pre-commercialization) through 2017 (three years post-commercialization). First, I measure the shift in collisions brought about by Washington's 2012 cannabis legalization. Then, I compare retail cannabis sales-a measure of commercialization-to traffic collisions based on severity of injury (fatal, severe injury, minor injury, non-injury, and all).

RESULTS

After controlling for confounding factors, evidence suggests that recreational cannabis legalization led to fewer fatal and serious injury collisions. Retail cannabis sales generally correlate with more traffic collisions, particularly for less severe (minor injury) crashes. These findings are robust to the inclusion of additional control variables pertaining to county-level cannabis usage and driving behavior while intoxicated.

CONCLUSIONS

Cannabis legalization led to fewer fatal, serious, and minor injury collisions. Commercialization (cannabis sales) correlated with an increase in less severe crashes. Although cannabis use generally increased in Washington State following legalization/commercialization, survey data suggest that driving behavior while under the influence of cannabis did not change significantly over the post-commercialization period. Future research should focus on measuring the dose-dependent impact of cannabis consumption on traffic collisions. This should include recognition of the importance of cannabis dosing, timing, and route of consumption. Lastly, the dangers of poly-drug driving-particularly cannabis and alcohol-are well established and should be high priority for further research.

A Research Agenda to Inform Cannabis Regulation: How Science Can Shape Policy

In the United States, changes to cannabis policy have outpaced scientific knowledge about cannabis, its effects, and the impacts of different policy approaches. Research barriers stem from key federal policies, including strict drug scheduling of cannabis, which comprehensively hinder the ability to conduct cannabis research, affecting state markets, evidence-based regulation, and scientific gains that could more effectively shape policy moving forward. The Cannabis Regulators Association (CANNRA) is a nonpartisan nonprofit organization that convenes and supports government agencies to facilitate information exchange and learning from existing cannabis regulations across US states and territories and other governmental jurisdictions. This commentary outlines a research agenda that, if implemented, would address critical gaps in the science that cannabis regulators have identified in terms of knowledge regarding: (1) medicinal use of cannabis; (2) cannabis product safety; (3) cannabis consumer behaviors; (4) policies to promote equity and reduce disparities, both in the industry and more broadly in communities affected by the past criminalization of cannabis; (5) policies to prevent youth consumption and promote public health and safety; and (6) policies to reduce the illicit market and associated harms. The research agenda outlined here is the result of both formal discussions through CANNRA-wide meetings and informal discussions cannabis regulators have had as part of CANNRA committees. This research agenda is not all encompassing but rather highlights areas of research that have vital importance for cannabis regulation and policy implementation. Although many organizations weigh in on research needs related to cannabis, cannabis regulators (ie, the individuals implementing policies legalizing cannabis in states and territories) have generally not had a voice at the table advocating for specific research to be conducted. Their perspective representing the government agencies closest to the ground in terms of experiencing the impacts of current cannabis policy is essential to furthering quality, practical research that can advance informed and effective policy.

Increase in driving after cocaine use in Spain: a cross-sectional dataset analysis for 2021

Objective

Driving under the influence of alcohol and/or drugs impairs skills essential for safe driving, increases the risk of being involved in a traffic accident and is particularly prevalent in Spain. The aim is to assess the prevalence of positive substance driving cases, what factors may be associated with driving after substance use, and the evolution of the progress in the prevalence of drug use among drivers in drivers based on the 2008, 2013, 2018, and 2021 studies.

Study design and setting

The present study was conducted in a representative sample of Spanish drivers in 2021 for alcohol (breath) and psychoactive substances [oral fluid (OF)]. The sample size was 2980 drivers, mostly males (76.5%) with a mean age of 41.35 ± 13.34 years.

Results

In 2021, 9.3% of drivers tested positive for alcohol and/or drugs. The presence of alcohol alone was observed in 4.2% of drivers, alcohol and another substance in 0.3%, a single drug in 4.4%, and two or drugs other than alcohol in 0.4%. Overall, cocaine cases were the highest registered in 2021 (2.4%), while cannabis (1.9%) and polydrug cases (0.7%) were the lowest, with respect to the 2008/2013/2018 studies.

Conclusions

According to our research, in 2021, 9 out of 100 drivers were detected to have some substance in their system. This prevalence remains unacceptably high in Spain, with a marked increase in the frequency of driving after cocaine use. Further interventions and measures must be taken to avoid driving under the influence of alcohol and/or drugs.

What contributes to drug driving? An exploratory investigation into the influence of problematic substance use, roadside testing and alternative transport options

Despite a strong reliance on enforcement approaches to prevent drug driving in Australia, this behaviour is still prevalent. The objective of this study was to investigate the influence of problematic drug use (i.e., showing indications of addiction), exposure to roadside drug testing, the use of detection avoidance strategies, and perceptions relating to alternative transport options on drug driving among illicit drug users. A total of 1,541 licensed drivers from the states of Queensland, New South Wales, and Victoria completed an online survey. The survey collected demographic and problematic substance use information, as well as items assessing drug driving behaviour. Cannabis was reported to be the most commonly used drug (36.0%); the most common drug of problematic use (27.9%), and the drug most often taken prior to driving (43.5%). Observing police operating Roadside Drug Tests (RDT) was more common among the participants than being tested by RDT (35.7% vs 23%). The results indicated a significant association between being a drug driver and observing or being tested by RDT. The drug drivers were significantly more likely to report using a range of strategies to avoid police detection than the non-drug drivers. Similarly, the drug drivers reported that it was more difficult for them to use various alternative transport options than the non-drug drivers. Decision tree analyses found that significant predictors of self-reported drug driving were problematic drug use, holding a provisional or probationary licence, earning a low- or middle-income, and using detection avoidance strategies like remaining watchful for police vehicles and taking back streets. The findings of this study suggest that ongoing improvements to drug driving enforcement will need to be complemented by health-based approaches designed to reduce drug abuse and dependence, and improvements to public transport, in order to achieve a sustainable reduction in drug driving.

Risk Perception of Traffic Accidents Due to Alcohol and Marijuana Use in Mexican College Students

Driving under the influence (DUI) of alcohol and other drugs is a common occurrence in Western societies. Alcohol consumption is related to 15% of fatal injuries in traffic accidents worldwide, with those DUI of alcohol being up to 18 times more likely to be involved in a fatal accident. Evidence for DUI of alcohol or marijuana among the college population in Mexico is scarce. This research estimates the proportion of use of alcohol and marijuana, describes the risk perception of DUI, and evaluates the relationship between risk perception and DUI behaviors in a sample of Mexican college students aged 18 to 29. The study was cross-sectional with a non-probabilistic sample. Risk perception of suffering traffic accidents when DUI or riding with someone DUI of alcohol, marijuana, or both, was high, unlike the risk perception of being detected or sanctioned for a DUI of marijuana. The study provided valuable information on the risk perception of engaging in behaviors related to DUI of alcohol and/or marijuana. It is necessary to undertake research on the subject with probabilistic and representative samples of this population of Mexico.

Associations of cannabis use with motor vehicle crashes and traffic stops among older drivers: AAA LongROAD study

BACKGROUND

Acute cannabis use is associated with a higher risk of motor vehicle crashes (MVC). This study aimed to determine if self-reported past-year cannabis use is associated with MVC or traffic stops among older drivers.

METHODS

This cross-sectional analysis used data from a multi-center study enrolling active drivers aged 65-79 years. Data regarding cannabis use, MVC, and traffic stops (i.e., being pulled over by police, whether ticketed or not) within the previous 12 months were collected through participant interviews. Log-binomial regression models examined associations of past-year cannabis use with MVC and traffic stops, adjusting for site and sociodemographic and mental health characteristics.

RESULTS

Of 2,095 participating older drivers, 186 (8.88%) used cannabis in the past year but only 10 (<0.5%) within an hour before driving in the last 30 days; 11.41% reported an MVC and 9.45% reported a traffic stop. Past-year cannabis users had a higher prevalence of MVC (adjusted prevalence ratio [aPR] = 1.38; 95%CI: 0.96, 2.00; p = 0.086) and traffic stops (aPR = 1.58; 1.06, 2.35; p = 0.024).

CONCLUSIONS

Past-year cannabis use was associated with increased traffic stops, which are correlated modestly with increased MVC in past studies and may indicate impaired driving performance. We did not find a statistically significant association of past-year cannabis use with MVC, which may indicate limited sustained effects on driving performance from periodic use among older adults, who report rarely driving immediately after use.

Driving Impairment in Movement Disorders

Background

Driving may be adversely affected by any movement disorder, but has been mostly studied in Parkinson's disease (PD). Few studies have addressed driving impairment in patients with Huntington's disease (HD); driving in other movement disorders such as dystonia, blepharospasm and Tourette syndrome (TS) has not been adequately evaluated.

Objectives

The aim of this review is to summarize the findings of driving impairment in movement disorders and evaluate the usefulness of clinical tools in guiding clinicians whether to refer patients for driving assessment.

Methods

A review of literature was performed on PubMed and articles on driving and movement disorders were identified using a Boolean phrase.

Results

We were able to identify 66 articles that fulfilled the target subject: impairment of driving in PD, cervical dystonia, blepharospasm, HD and TS. We also included articles discussing the role of driving rehabilitation in patients with movement disorders.

Conclusions

Driving is often impaired in patients with PD and other movement disorders not only due to motor symptoms but also because of cognitive and behavioral co-morbidities. Certain screening tools may be helpful in guiding the clinician in referring the patients for driving assessment.

Crash-involved THC-positive drivers in Norway have a high frequency of polysubstance use

BACKGROUND

Tetrahydrocannabinol (THC) is the most frequently detected drug in blood samples from apprehended drug driving suspects in Norway. This investigation aimed to study the extent of polysubstance use among apprehended crash-involved drivers with THC concentrations above the legal limit and explore the importance of THC in polysubstance cases.

METHODS

We selected all drug driving cases where blood samples had been submitted for forensic toxicology testing after involvement in road traffic crashes during 2013-2020, except drivers who were fatally injured.

RESULTS

Twenty percent (n = 2133) of the 10,520 apprehended crash-involved drivers had concentrations of THC in their blood above the legal limit of 1.3 ng/mL, and 84 % of those also had concentrations of alcohol or other drugs above the legal limits; 61 % for sedatives, 38 % for stimulants, 33 % for alcohol, and 10 % for opioids. The most frequent substance combination was cannabis together with sedatives and stimulants (22.9 %; n = 488). Polysubstance use was least common among drivers under 24 years. The proportion of drivers with THC > 5 ng/mL was highest if the blood sample was collected within 90 min after the crash, and when only THC was detected. There was a statistically significant inverse association between THC > 5 ng/mL and concentrations of alcohol or amphetamines at the highest sanction level.

CONCLUSIONS

Most apprehended crash-involved THC-positive drivers also tested positive for other psychoactive substances. Drivers with high blood THC concentrations had less often high concentrations of other substances; cannabis might then have been a more important contributor to impairment.

Alcohol and cannabis use in traffic-related injuries in Mexico City

BACTERKGROUND

There is debate on whether cannabis affects road traffic injuries (RTIs) separately from the effects of alcohol. Our goals are to report the possible increase in risk of an RTI among alcohol and cannabis users by type of exposure (biological, self-reported and combined) and the possible interaction of alcohol and cannabis in patients with an RTI in an emergency department in Mexico City.

METHODS

A case-crossover study with 433 cases of RTI (as a pedestrian, driver or passenger) during the period January-April 2022. A breath sample, an oral sample for cannabis detection and self-reported alcohol and cannabis use 6 hours prior to the RTI and in two control periods were used. We report ORs and 95% CIs from conditional logistic regressions for the case-crossover estimates.

RESULTS

Alcohol alone increased the risk of an RTI (OR=6.02, 95% CI 3.29 to 10.99) for most RTIs, regardless of whether we used information from self-reports or a breath sample in the hazard period. Conversely, cannabis only increased the RTI when we added information in the hazard period from self-reports or oral samples. Nevertheless, this increase in risk disappeared (OR=2.06, 95% CI 0.90 to 4.70) among those who only used cannabis. We also found no evidence of interaction between alcohol and cannabis in the risk of an RTI.

CONCLUSIONS

Alcohol is the most commonly used substance in Mexico and a high-risk factor for RTI in Mexico City. Although cannabis alone was not associated with an RTI, continuous monitoring of its effects is required.

Global, Regional, and National Burden of Road Injuries from 1990 to 2019

(1) Background: Understanding occurrence can help formulate effective preventative laws and regulations. However, the most recent global burden and road injuries (RIs) trends have not been reported. This study reports the burden of RIs globally from 1990 to 2019. (2) Methods: RIs data were downloaded from the Global Burden of Disease 2019. Incidence, deaths, and disability-adjusted life years (DALYs) described the trend and burden of RIs. We calculated age-standardized rates (ASRs) and estimated annual percentage change (EAPC) for the above indexes to evaluate the temporal trend of RIs. We evaluated the social-demographic index (SDI) with epidemiological RI parameters and reported proportions of age-standardized rates due to RI. (3) Results: In 2019, the global incidence of RIs reached 103.2 million. The EAPC of RI incidence increased, whereas deaths and DALYs decreased. Age-standardized incident rate (ASIR) was highest in low-middle SDI regions, age-standardized death rate (ASDR) was high in middle SDI regions, and age-standardized DALYs increased in low SDI regions. The highest accident rates were found in those aged 20-24 years old. Cyclist injuries were the leading RIs (34%), though pedestrian and motor vehicle accidents were the leading cause of death (37.4%, 37.6%) and DALYs (35.7%, 32.3%), respectively. (4) Conclusions: Over the past 30 years, RIs incidence increased annually, though death and DALY rates decreased. RIs places a considerable burden on public health in low SDI countries. Data should be used to develop and implement effective measures to reduce the burden of RIs.

Waiting for the Stop Sign to Turn Green: Contemporary Issues on Drug and Alcohol Impaired Driving Policy

Impaired driving has been a considerable social problem in the U.S. for decades, but efforts to reduce it have stalled after the initial reductions in the 1980's. As a result, legislators continue to develop more polices aimed at deterring impaired driving. Although alcohol has historically been the focus of these efforts, recently there has been increased concern about marijuana impaired driving policies as well. However, alcohol and marijuana impaired driving differ in many ways. This paper explores the costs and benefits of new zero-tolerance policies such as the reduction of the per-se Blood Alcohol Concentration (BAC) level from .08 to .05 for alcohol and the establishment of similar per-se limits for marijuana. These policies are not based on actual impairment and reflect a net widening effect that will criminalize unimpaired drivers, divert criminal justice resources away from the most problematic impaired drivers, and will have little impact on impaired driving crashes. As such, they have the potential to do more harm than good.

A study of self-reported personal cannabis use and state legal status and associations with engagement in and perceptions of cannabis-impaired driving

Objective: The objectives of the current study were to (1) characterize predictors of perceived risk of driving within 2 h of cannabis use and driving after cannabis use in a sample of adults who have used cannabis in the past year and (2) determine whether the influence of these predictors vary by state legalizations status.Methods: Data for this study were from online surveys. Study participants from Colorado, Iowa, and Illinois were included if they reported being between 25 and 40 years old and had a history of cannabis use. Outcome variables included (1) days of cannabis use per month, (2) reported driving within 2 h of cannabis use (vs. not driving within 2 h as reference), (3) proportion of driving after cannabis use days per month (days of driving a car within 2 h of cannabis use per month/days of cannabis use per month), and (4) perception of safety of driving after cannabis use. Potential predictors included age of first use of cannabis, gender, education status, and state of residence. The SAS GLMSELECT Procedure was used for the analysis.Results: Increased age of first use of cannabis was associated with decreased days of cannabis use per month (B = -0.51 days/month per year), a reduction in the proportion of driving after cannabis use days per month (B = -0.02 per month), and decreased perception of safety of driving after cannabis use (B = -0.06 per year). Female gender was also associated with less use (B = -2.3 days per month), a lower proportion of driving following use (B = -0.06 days driving/days used), and decreased perception of safety (B = -0.29). In addition, residents of Colorado reported using the most days, had the highest likelihood of driving within 2 h of use, and had the most positive perceptions of being able to safely drive after cannabis use.Conclusions: The delay in onset of cannabis use may mitigate its use among adults and driving after cannabis use. This has important implications for driver safety. Intervention programs for reducing cannabis's effects on driving should focus on individuals with early onset of use, male drivers, and drivers in states where cannabis for adult recreational use is legalized.

The effects of oral and vaporized cannabis alone, and in combination with alcohol, on driving performance using the STISIM driving simulator: A two-part, double-blind, double-dummy, placebo-controlled, randomized crossover clinical laboratory protocol

The legalization of cannabis for medicinal and non-medicinal purposes, and the corresponding increase in diversity of cannabis products, has resulted an urgent need for cannabis regulatory science. Among the most pressing needs is research related to impairment due to cannabis exposure, especially on driving performance. The present project was designed to evaluate the impact of oral and vaporized cannabis, when administered alone or in combination with alcohol, on simulated driving performance (STISIM driving simulator), cognitive/psychomotor ability, and field sobriety performance. Healthy adults will complete two, double-blind, double-dummy, placebo-controlled, randomized crossover clinical laboratory studies, one with oral cannabis (16 men/16 women) and the second with vaporized cannabis (16 men/16 women). In each study, participants will complete seven experimental sessions during which acute doses of placebo or high Δ9-THC cannabis containing 0, 10, or 25 mg Δ9-THC will be administered both alone and in combination with placebo or alcohol-containing beverages (target breath alcohol concentrations, BAC, of 0.0% or 0.05%). A positive control session (i.e., alcohol at target BAC of 0.08% with placebo cannabis) will also be completed. Simulated driving performance tests (available for download; see Methods), field sobriety assessments, subjective drug effect questionnaires, a mobile device impairment test (DRUID app), and collection of whole blood specimens will be completed repeatedly during each session. Linear mixed models will be used to test for differences across experimental conditions and a priori planned comparisons will be used to determine differences between conditions of interest (e.g., cannabis alone vs cannabis with alcohol). This research is designed to extend prior studies of cannabis and alcohol on driving performance by using oral and vaporized routes of cannabis administration. By increasing understanding of impairment associated with co-use of alcohol and these novel forms of cannabis, this research could inform impairment detection standards for cannabis and alcohol and have important implications for law enforcement, public policy decisions regarding accessibility of these substances, and education of the general population who may use cannabis and/or alcohol. Lastly, this manuscript provides interested researchers with access to the simulated driving scenarios and data extraction tools developed for this study as a means of facilitating future cross-study comparisons, which is important given the heterogeneity in methods used across laboratories in prior research.