Preventing cannabis users from driving under the influence of cannabis

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 systematic review of factors associated with illegal drug driving

Drug driving is a serious problem worldwide that can increase the risk of road crashes. This systematic review seeks to identify factors associated with drug driving (i.e., driving after consuming drugs other than alcohol) to highlight gaps in existing knowledge and inform the design of more effective countermeasures. A search of the literature was conducted for the period January 1, 2005 to July 31, 2021 using six different databases. The search protocol followed PRISMA guidelines and was registered in PROSPERO (#CRD42021234616). Studies that met inclusion criteria compared drug drivers with either non-drug drivers, alcohol-only drivers or drug drivers from an earlier time period, to identify factors specifically associated with drug driving, rather than common to all drivers. Two hundred and nineteen publications met the inclusion criteria and were included within the review. Based on the findings, a logic model was developed that presents the factors associated with drug driving. Various sociodemographic, psychosocial and legal factors emerged as the main factors associated with illegal drug driving. At the sociodemographic and psychological levels, drug drivers were more likely to be single, young males who often drive after using cannabis and who score high on sensation-seeking and impulsivity scales. The key social factor found to be associated with drug driving was peer acceptance/disapproval of the behaviour. At the legal level, the review suggested that the effectiveness of current enforcement approaches to drug driving vary among jurisdictions around the world due to differences in the level of perceived certainty of apprehension and the chances of punishment avoidance. Future research into the anticipated and actual rewards for drug driving is needed to inform the development of more effective countermeasures.

Interventions to Prevent Drugged Driving: A Systematic Review

CONTEXT

Literature suggests that cannabis legalization may increase fatal motor vehicle collisions. However, evidence on the effectiveness of interventions to prevent drugged driving is limited.

EVIDENCE ACQUISITION

MEDLINE, PsycINFO, Web of Science, Embase, SafetyLit, Criminal Justice Database, Transport Research International Documentation, bibliographies, and relevant gray literature were searched systematically through May 2020. Randomized and nonrandomized studies of preventive interventions measuring drugged driving outcomes were included. Evidence certainty was judged per Grading of Recommendations Assessment, Development, and Evaluation guidelines to designate quality ratings from very low to high.

EVIDENCE SYNTHESIS

The search identified 11 RCTs and 17 nonrandomized studies conducted predominantly among youth (aged 15-25 years; n=33,711 of 37,117 active research participants). In the public, cannabis packaging with health warnings increases the knowledge about drugged driving effects (high certainty); roadside drug testing can reduce drugged driving among cannabis users (moderate certainty); media campaigns may increase deterrent attitudes and knowledge (low certainty); and state sanctions, including traffic offense criminalization, license withdrawal, and per se drugged driving laws, may have little or no effect on drug-related fatalities or injuries (very low-low certainty). For youth or previous offenders, motivational interviewing can prevent drugged driving and driver education programs can increase knowledge (moderate certainty), whereas drug abuse prevention, substance abuse treatment, and driver rehabilitation may prevent drugged driving (very low certainty).

CONCLUSIONS

Overall, there is evidence to support the interventions that may improve drugged driving knowledge, attitudes, and behaviors. However, the impact of such interventions on measures of drugged driving-related morbidity and mortality is uncertain. Further research is urgently required to address these gaps in knowledge.

Perceived safety of cannabis intoxication predicts frequency of driving while intoxicated

Driving under the influence of cannabis (DUIC) is a public health concern, and data are needed to develop screening and prevention tools. Measuring the level of intoxication that cannabis users perceive as safe for driving could help stratify DUIC risk. This study tested whether intoxication levels perceived as safe for driving predicted past-month DUIC frequency. Online survey data were collected in 2017 from a national sample of n = 3010 past-month cannabis users with lifetime DUIC (age 18+). Respondents indicated past-month DUIC frequency, typical cannabis intoxication level (1-10 scale), and cannabis intoxication level perceived as safe for driving (0-10 scale). Approximately 24%, 38%, 13%, and 24% of respondents engaged in DUIC on 0, 1-9, 10-19, and 20-30 days respectively in the past month. Among these four DUIC frequency groups, median typical intoxication varied little (5-6), but median intoxication perceived as safe for driving varied widely (3-8). Higher intoxication levels perceived as safe for driving corresponded to frequent DUIC (Spearman's rho: 0.46). For each unit increase in intoxication level perceived as safe for driving, the odds of past-month DUIC increased 18% to 68% (multinomial logistic regression odds ratio - MOR1-9 days: 1.18, 95% CI: 1.13-1.23; MOR10-19 days: 1.40, 95% CI: 1.30-1.50; MOR20-30 days: 1.68, 95% CI: 1.57-1.80). In this targeted sample of past-month cannabis users, DUIC frequency varied widely, but daily/near-daily DUIC was common (24%). Measuring intoxication levels perceived as safe for driving permits delineation of past-month DUIC frequency. This metric has potential as a component of public health prevention tools.

Correlation of Breath and Blood Δ9-Tetrahydrocannabinol Concentrations and Release Kinetics Following Controlled Administration of Smoked Cannabis

BACKGROUND

Cannabis use results in impaired driving and an increased risk of motor vehicle crashes. Cannabinoid concentrations in blood and other matrices can remain high long after use, prohibiting the differentiation between acute and chronic exposure. Exhaled breath has been proposed as an alternative matrix in which concentrations may more closely correspond to the window of impairment; however, efficient capture and analytically sensitive detection methods are required for measurement.

METHODS

Timed blood and breath samples were collected from 20 volunteers before and after controlled administration of smoked cannabis. Cannabinoid concentrations were measured using LC-MS/MS to determine release kinetics and correlation between the 2 matrices.

RESULTS

Δ9-Tetrahydrocannabinol (THC) was detected in exhaled breath for all individuals at baseline through 3 h after cannabis use. THC concentrations in breath were highest at the 15-min timepoint (median = 17.8 pg/L) and declined to <5% of this concentration in all participants 3 h after smoking. The decay curve kinetics observed for blood and breath were highly correlated within individuals and across the population.

CONCLUSIONS

THC can be reliably detected throughout the presumed 3-h impairment window following controlled administration of smoked cannabis. The findings support breath THC concentrations as representing a physiological process and are correlated to blood concentrations, albeit with a shorter window of detection.

International Perspectives on the Implications of Cannabis Legalization: A Systematic Review & Thematic Analysis

The legality, recreational and medical use of cannabis varies widely by country and region but remains largely prohibited internationally. In October 2018, Canada legalized the recreational use of cannabis—a move many viewed as controversial. Proponents of legalization have emphasized the potential to eradicate the marijuana black market, improve quality and safety control, increase tax revenues, improve the availability of medical cannabis, and lower gang-related drug violence. Conversely, opponents of legalization have stressed concerns about cannabis’ addictive potential, second-hand cannabis exposure, potential exacerbation of underlying and established mental illnesses, as well as alterations in perception that affect safety, particularly driving. This systematic review synthesizes recent international literature on the clinical and public health implications of cannabis legalization.

Exploring perceptions among people who drive after cannabis use: Collision risk, comparative optimism and normative influence

INTRODUCTION AND AIMS

While the perceived risks of driving under the influence of cannabis (DUIC) have been a focus of recent drug-driving research, relevant concepts from the social cognition literature have rarely been applied to inform understanding of DUIC. This study aims to expand knowledge of perceived collision risk and social influences associated with DUIC and driving after other substance use.

DESIGN AND METHODS

Semi-structured interviews were conducted with 20 participants of a remedial program for impaired drivers. Thematic analysis began with two independent coders. Early discussion of emergent themes resulted in the identification of applicable social cognition concepts, resulting in selective coding and interpretation.

RESULTS

Many participants identified DUIC as less risky than driving under the influence of alcohol or other drugs. Mixed perceptions regarding the dangerousness of DUIC were expressed, with some participants denying increased collision risk except among novice cannabis users. Comparative optimism bias was also expressed by participants who perceived themselves as less likely than others to be involved in a collision when DUIC. In view of normative influence, friends were generally seen as more accepting of DUIC than family, and there were indications that the opinions of others who use cannabis were regarded as more credible than the opinions of those who do not use the drug.

DISCUSSION AND CONCLUSIONS

Comparative optimism bias and normative influence may contribute to perceived risks associated with DUIC and may, therefore, be useful concepts to employ to increase the effectiveness of public health and road safety initiatives.

Toxicological Investigation of Drug-Related Cases in Greece: Interpretation of Analytical Findings

The process of toxicological analysis of postmortem specimens can reveal some special difficulty compared to the clinically derived specimens. Many drugs are not stable and the chemical changes that occur in the specimens, due to the hydrolysis processing, the time passed, the drug metabolism, and matrix effect, even when the postmortem interval is short, may affect the interpretation of the toxicological results. This interpretation may be critical, not only to the thorough investigation of different kind of forensic cases, but also to clinical or other cases as it provides very significant challenges to the scientists. This article reviews (a) particular toxicological issues associated with some toxic substances responsible for common lethal or nonlethal poisonings, such as opiates, cannabis, and cocaine and the vast number of factors that affect drug concentration; and (b) focuses on toxicological issues associated with the analytical findings of certain postmortem specimens. The toxic substances cited in the present paper are the most commonly found in forensic cases in Greece. The investigation of these drug-related deaths has revealed that heroin, alone or in combination with other psychoactive substances, such as cannabis and cocaine, is the main drug involved in these deaths.

A Burning Problem: Cannabis Lessons Learned from Colorado

With recent increases in cannabis' popularity, including being legalized in several states, new issues have emerged related to use. Increases in the number of users, new products, and home growing all present distinct concerns. In the present review, we explored various cannabis-related concerns (i.e. use, acquiring, growing, and public health/policy) that have arisen in Colorado in order to provide information on emerging issues and future directions to mitigate negative outcomes that could occur in states considering, or that already have implemented, a legalized cannabis market. Specific to Colorado, issues have arisen related to edibles, vaporizers/'e-cannabis', concentrates, growing, quantifying use, intoxicated driving, and arrests. Understanding cannabis dosing (including dose-dependent effects and related consequences), standardizing quantities, evaluating the safety of new products, and developing harm reduction interventions are important next steps for informing public policy and promoting health and well-being. Overall, increasing our knowledge of emerging issues related to cannabis is key to promoting the benefits and combating the potential harms of cannabis, especially for states legalizing medical or recreational cannabis.

International approaches to driving under the influence of cannabis: A review of evidence on impact

BACKGROUND

There are knowledge gaps regarding the effectiveness of different approaches designed to prevent and deter driving under the influence of cannabis (DUIC). Policymakers are increasingly interested in evidence-based responses to DUIC as numerous jurisdictions worldwide have legally regulated cannabis or are debating such regulation. We contribute a comprehensive review of international literature on countermeasures that address DUIC, and identify where and how such measures have been evaluated.

METHODS

The following databases were systematically searched from 1995 to present: Medline, Embase, PsycINFO, CINAHL, Sociological Abstracts, and Criminal Justice Abstracts. Hand searching of relevant documents, internet searches for grey literature, and review of ongoing email alerts were conducted to capture any emerging literature and relevant trends.

RESULTS

Numerous international jurisdictions have introduced a variety of measures designed to deter DUIC. Much interest has been generated regarding non-zero per se laws that set fixed legal limits for tetrahydrocannabinol and/or its metabolites detected in drivers. Other approaches include behavioural impairment laws, zero-tolerance per se laws, roadside drug testing, graduated licensing system restrictions, and remedial programs. However, very few evaluations have appeared in the literature.

CONCLUSIONS

Although some promising results have been reported (e.g., roadside testing), it is premature to draw firm conclusions regarding the broader impacts of general deterrent approaches to DUIC. This review points to the need for a long-term commitment to rigorously evaluate, using multiple methods, the impact of general and specific deterrent DUIC countermeasures.

Driving under the influence among frequent ecstasy consumers in Australia: trends over time and the role of risk perceptions

BACKGROUND

Driving under the influence (DUI) of alcohol and illicit drugs is a serious road safety concern. This research aimed to examine trends in DUI across time and changes in attitudes towards the risks (crash and legal) associated with DUI among regular ecstasy users (REU) interviewed in Australia.

METHODS

Participants were regular (at least monthly) ecstasy users surveyed in 2007 (n=573) or 2011 (n=429) who had driven a car in the last six months. Face to face interviews comprised questions about recent engagement of DUI and roadside breath (alcohol) and saliva (drug) testing. Participants also reported the risk of crash and of being apprehended by police if DUI of alcohol, cannabis, ecstasy, and methamphetamine.

RESULTS

There were significant reductions in DUI of psychostimulants (ecstasy, methamphetamine, cocaine, LSD) but not alcohol or cannabis between 2007 and 2011. This was accompanied by increased experience of roadside saliva testing and increases in crash and legal risk perceptions for ecstasy and methamphetamine, but not alcohol or cannabis. When the relationship between DUI and risk variables was examined, low crash risk perceptions were associated with DUI of all substances and low legal risk perceptions were associated with DUI of ecstasy.

CONCLUSIONS

The observed reduction in DUI of psychostimulants among frequent ecstasy consumers may be related to increased risk awareness stemming from educational campaigns and the introduction of saliva testing on Australian roads. Such countermeasures may be less effective in relation to deterring or changing attitudes towards DUI of cannabis and alcohol among this group.

Cannabis effects on driving skills

BACKGROUND

Cannabis is the most prevalent illicit drug identified in impaired drivers. The effects of cannabis on driving continue to be debated, making prosecution and legislation difficult. Historically, delays in sample collection, evaluating the inactive Δ(9)-tetrahydrocannabinol (THC) metabolite 11-nor-9-carboxy-THC, and polydrug use have complicated epidemiologic evaluations of driver impairment after cannabis use.

CONTENT

We review and evaluate the current literature on cannabis' effects on driving, highlighting the epidemiologic and experimental data. Epidemiologic data show that the risk of involvement in a motor vehicle accident (MVA) increases approximately 2-fold after cannabis smoking. The adjusted risk of driver culpability also increases substantially, particularly with increased blood THC concentrations. Studies that have used urine as the biological matrix have not shown an association between cannabis and crash risk. Experimental data show that drivers attempt to compensate by driving more slowly after smoking cannabis, but control deteriorates with increasing task complexity. Cannabis smoking increases lane weaving and impaired cognitive function. Critical-tracking tests, reaction times, divided-attention tasks, and lane-position variability all show cannabis-induced impairment. Despite purported tolerance in frequent smokers, complex tasks still show impairment. Combining cannabis with alcohol enhances impairment, especially lane weaving.

SUMMARY

Differences in study designs frequently account for inconsistencies in results between studies. Participant-selection bias and confounding factors attenuate ostensible cannabis effects, but the association with MVA often retains significance. Evidence suggests recent smoking and/or blood THC concentrations 2-5 ng/mL are associated with substantial driving impairment, particularly in occasional smokers. Future cannabis-and-driving research should emphasize challenging tasks, such as divided attention, and include occasional and chronic daily cannabis smokers.

Substance-related traffic-risk behaviors among college students

AIMS

Drunk driving is a major public health concern, but drugged driving has received little attention. This study examines drugged driving and riding with a drugged driver in a college student sample, in terms of prevalence, age-related trends, race/sex differences, overlap with drunk driving, and risk for alcohol and marijuana dependence.

METHODS

Students (N=1194) ages 19-22 were interviewed annually for 3 years about past-year frequency of drugged driving, riding with a drugged/drunk driver, drunk driving, access to a car, and alcohol/drug dependence. Annual follow-up rates were excellent (88-91%). Repeated measures analyses were conducted using generalized estimating equations (GEE).

RESULTS

One in six (17%(wt)) 19-year-olds with access to a car drove drugged in the past year; prevalence remained stable through age 22. Drugged driving was more prevalent among males (p<.001) and whites (p<.01). Riding with a drugged driver varied by race and sex (overall prevalence 28%(wt) at age 19), was stable from age 19 to 21, and decreased by age 22 (p<.05). Annually, half of drugged drivers also drove drunk (ranges between 47% and 60%). Both drugged and drunk driving were independently associated with increased risk for alcohol dependence, holding constant age, sex, and race. Drunk driving did not add to the risk for marijuana dependence in the context of drugged driving.

CONCLUSIONS

The prevalence of drugged driving is similar to drunk driving among college students. Both are strongly associated with underlying alcohol and drug dependence. Prevention and treatment implications are discussed.

Abuso e dependência de maconha: comparação entre sexos e preparação para mudanças comportamentais entre usuários que iniciam a busca por tratamento

OBJETIVOS: Descrever o perfil sociodemográfico de usuários de maconha que iniciam tratamento e comparar os sexos dos indivíduos em relação aos estágios de prontidão para mudança e uso associado de outras drogas. MÉTODO: Estudo transversal descritivo, com amostra não probabilística de indivíduos que ligaram para um teleatendimento especializado em dependência química. RESULTADOS: A amostra se constituiu de 72% de indivíduos do sexo masculino na faixa etária de 12 a 25 anos. Um percentual de 85,5% fazia uso associado de outras drogas. O estágio motivacional predominante foi de ação (56%), sem diferenças entre sexos (p = 0,4). Os homens mais frequentemente procuraram auxílio para o tratamento do uso de maconha. CONCLUSÕES: Com base nesses dados, foi possível delinear o perfil dos usuários de maconha para auxiliar no direcionamento de informações e atendimento adequado.

Predictors of driving after alcohol and drug use among adolescents in Valencia (Spain)

BACKGROUND

Driving under the influence of alcohol and drugs has been identified as a risk factor for road traffic crashes. We have assessed the prevalence and predictor factors for driving after alcohol and drug use by adolescents.

METHODS

A cross-sectional survey involving 11,239 students aged 14-18 years from 252 private and public schools in the Valencia region of Spain was conducted. The prevalence and predictors of driving after alcohol use, alcohol and drug use, or drug use during the previous 6 months were measured.

RESULTS

Of the students who reported driving (20%), 45.1% indicated driving after alcohol and drug use. The consumption of various drugs was higher among students who drove a vehicle compared with those who did not. The likelihood of driving after consuming alcohol, or alcohol and drugs, increased in line with the number of standard drink units per week, reports of any lifetime alcohol- or drug-related problems, and poor family relationship. In addition, masculine gender and early alcohol use increased the likelihood of driving after consuming alcohol.

CONCLUSIONS

Driving after alcohol and drug use is quite prevalent among adolescents in the Valencia region of Spain. There is a need for implementation of targeted policies for adolescents. This should focus on education and information on alcohol/drug use and driving.

Typologies of cannabis users and associated characteristics relevant for public health: a latent class analysis of data from a nationally representative Canadian adult survey

Cannabis is the most prevalently used illicit drug in Canada. Current policy consists primarily of universal use prohibition rather than interventions targeting specific risks and harms relevant for public health. This study aimed to identify distinct groups of cannabis users based on defined use characteristics in the Canadian population, and examine the emerging groups' associations with differential risk and harm outcomes. One thousand three hundred and three current (i.e. use in the past three months) cannabis users, based on data from the representative cross-sectional 2004 Canadian Addiction Survey (N = 13,909), were statistically assessed by a 'latent class analysis' (LCA). Emerging classes were examined for differential associations with socio-demographic, health and behavioral indicators on the basis of chi-square and analysis of variance techniques. Four distinct classes based on use patterns were identified. The class featuring earliest onset and highest frequency of use [22% of cannabis user sample or 2.2% (95% confidence interval (CI) = 1.8-2.7%) of the Canadian adult population] was disproportionately linked to key harms, including other illicit drug use, health problems, cannabis use and driving, and cannabis use problems. A public health framework for cannabis use is needed in Canada, meaningfully targeting effective interventions towards the minority of users experiencing elevated levels of risks and harms.

Factors associated with driving under the influence of alcohol and drugs among an Australian sample of regular ecstasy users

The aim of the present study was to investigate factors associated with driving under the influence (DUI) of alcohol and other drugs (ecstasy, cannabis and methamphetamine) among a group of regular ecstasy users. Participants were those who participated in the Australian Ecstasy and related Drug Reporting System (EDRS) in 2007 and had recently driven a motor vehicle (n=573). Participants were administered a semi-structured face-to-face interview which included questions about ecstasy and other drug use, associated health-related issues, and risk behaviours. Close to half of those who were current consumers of ecstasy, cannabis, and methamphetamine had recently driven under the influence of these drugs, while two-fifths of current alcohol users reported recent drink driving. Frequency of use for each substance was the most significant correlate of DUI of alcohol, cannabis, and methamphetamine, suggesting that interventions targeting high frequency and problematic drug use may be useful in reducing the occurrence of DUI for these substances. Low perception of the likelihood of having an accident was the most significant correlate of DUI of ecstasy and also related significantly to DUI of other substances. Perceptions of low likelihood of being apprehended by police and demographic characteristics such as younger age and male sex were also weakly associated with DUI. Together these findings have important implications for targeted interventions aimed at reducing the occurrence of DUI among regular drug users.

Hazardous use of gamma hydroxybutyrate: driving under the influence

Focus group discussions elicited descriptive experiences of driving under the influence of gamma hydroxybutyrate (GHB), and uncovered motivations that led participants to decide whether to get behind the wheel after ingesting this illegal psychoactive substance. Of the 51 current and past users interviewed, average age 31.1 +/- 7.7 years, 40% were female. All were recruited from the San Francisco Bay Area, in 2004. Factors making users vulnerable to adverse complications of driving while under the influence of GHB are also examined. Study limitations were noted. Implications for various law enforcement agencies and health professionals are derived from the data.

Correlates of driving under the influence of cannabis

BACKGROUND

Identifying cannabis users who are most at risk of driving under the influence of cannabis (DUIC) has important implications for drug treatment and prevention efforts. This paper examined correlates of DUIC among a purposive sample of recent cannabis users.

METHODS

Interviews were carried out among a cross-sectional sample of 320 Australian cannabis users. Past-year prevalence of DUIC (without using alcohol or other drugs) was regressed against a range of potential predictor variables.

RESULTS

Use of multiple drugs, believing that DUIC does not increase accident risk and cannabis dependence all predicted likelihood of DUIC. There was an interaction between age of first cannabis use and gender, whereby earlier onset cannabis use predicted DUIC but only among women.

CONCLUSIONS

The correlates of drug driving reflected cannabis users' beliefs about the dangers of cannabis use as well as their patterns of drug consumption. The emergence of cannabis dependence and age of onset as predictors of DUIC suggests a clearly defined role for treatment and prevention efforts in reducing the potential harms associated with DUIC.