Self-reported driving behaviour and attitudes towards driving under the influence of cannabis among three different user groups in England

doi:10.1016/j.addbeh.2004.08.007

Addictive Behaviors

Volume 30, Issue 3, March 2005, Pages 619-626

https://doi.org/10.1016/j.addbeh.2004.08.007 Get rights and content

Abstract

The study characterized self-reported driving behaviour, attitudes towards driving and assumptions about the effects of cannabis on driving, among two different volunteer groups: 63 regular cannabis users (RCUs; cannabis use>monthly) and 46 undergraduate student users, all from the West Midlands. More detailed information was provided by structured interviews with an additional sample of 23 regular users from southern England. Within each group, many respondents had driven whilst under the influence of cannabis (regular users, 82%; students, 40%; interviewees, 100%). Majorities among the regular users and interviewees continued to do so at least monthly. Most users believed that cannabis impaired driving only slightly. More stops by the police for drug-driving than for drink-driving were reported, but these rarely resulted in conviction and were not deterrent. Hence, cannabis users are very willing to drive after using the drug (often combined with alcohol), and even while intoxicated. They consider its effects on driving to be minimal; indeed, many consider it to promote better driving. Attitudes towards drink-driving were much more negative. Finally, most interviewees said that roadside drug testing would be the only efficacious deterrent to drug-driving.

Introduction

Epidemiological and experimental data support the notion that cannabis use is detrimental to car-handling skills. For example, there are many reports that, after alcohol, cannabis is the most frequently detected psychoactive drug in casualties of road traffic accidents (e.g., Cimbura et al., 1986, Mason & McBay, 1984, Mercer & Jeffrey, 1995), and in drivers arrested for erratic driving (e.g., Gjerde & Kinn, 1991). Furthermore, laboratory-based driving simulator tests have supported the view that cannabis impairs behaviours relevant to driving (e.g., Rafaelson et al., 1973, Robbe, 1994). However, there is still a dearth of information concerning actual driving habits under the influence of cannabis, and the factors that influence the decision to drive (or act as a deterrent). Robbe (1994) reported that cannabis users are aware that their driving is impaired by the drug, but are still willing to drive after using it. In a recent survey in Scotland (Neale, McKeganey, Hay, & Oliver, 2001), drug users reported driving more frequently after using cannabis than after any other illicit drug, but they perceived their driving to be less dangerous following cannabis use. The present two-part study first surveyed the attitudes and behaviour of a sample of regular cannabis users (RCUs) from the West Midlands towards driving after using cannabis. Driving habits after drinking alcohol, and attitudes towards drink-driving, were assessed for comparative purposes. A sample of university students was also surveyed, since cannabis use is widespread amongst university students (e.g., Webb, Ashton, Kelly, & Kamali, 1996), and they represent a group from which long-term, regular users are likely to emerge. The second phase of the study used structured interviews of a separate sample of regular cannabis users to provide a more detailed characterization of the self-reported physical and psychological effects of cannabis and alcohol on driving performance.

Section snippets

Methods

A questionnaire addressing drug use and driving habits was screened using three daily cannabis-using volunteers, and revised. A “snowball” method of recruitment was adopted, whereby self-declared regular cannabis users (RCUs; cannabis use>monthly) distributed questionnaires to other RCUs known to them, and they in turn passed on questionnaires to others. Eighty questionnaires were distributed within the West Midlands (Birmingham, Coventry, Wolverhampton), of which 68 (85%) were returned via the

Participant characteristics, patterns of drug use and driving behaviour

As might be expected, the RCUs were generally older than the students, and they used cannabis more frequently (Table 1). Other illicit drug use was lower among the students, but for both groups, the rank ordering of prevalence was similar (use of amphetamines>MDMA>LSD>cocaine). Levels of alcohol consumption were also similar between groups (Table 1). Nearly all of the RCUs (96.8%) were drivers, and a high proportion of these (91.8%) would drive at least weekly. Fewer students drove (87%), and

Discussion

Perhaps the most important questionnaire finding was that the prevalence of driving under the influence of cannabis is disturbingly high, not only among the RCUs who were drivers (82%), but also among less experienced student users (40%). The willingness of so many respondents to drive after cannabis is consistent with the finding that a majority of each sample considered their driving to be (at most) only slightly impaired by cannabis. Although the sample of regular users was largely

Acknowledgments

Funding for the study was kindly provided by the Alcohol Education and Research Council and the School of Psychology, University of Birmingham. An incomplete subset of some of these data was used for comparative purposes in Appendix A of TRL Report 477 for the Department of the Environment, Transport and the Regions.

References (9)

H. Gjerde et al.
Impairment in drivers due to cannabis in combination with other drugs
Forensic Science International
(1991)
G.W. Mercer et al.
Alcohol, drugs and impairment in fatal traffic accidents in British-Columbia
Accident Analysis and Prevention
(1995)
E. Webb et al.
Alcohol and drug use in UK university students
The Lancet
(1996)
G. Cimbura et al.
Incidence and toxicological aspects of cannabis and ethanol detected in 1394 fatally injured drivers and pedestrians in Ontario (1982–1984)
Journal of Forensic Sciences
(1986)

There are more references available in the full text version of this article.

Cited by (66)

Predicting changes in driving performance in individuals who use cannabis following acute use based on self-reported readiness to drive
2024, Accident Analysis and Prevention
It is unclear to what extent individuals who use cannabis can accurately assess their ability to drive safely following cannabis use, and lack of understanding as to what factors influence changes in driving performance following cannabis use. This research explores whether self-reported readiness to drive (RTD) and previous experience (PE) using cannabis within 2 h of driving can predict observed changes in driving performance following acute cannabis use.
Individuals who used cannabis at least monthly completed a baseline simulated drive, were dosed with cannabis of approximately 6.18% THC, then drove at approximately 30-minutes, 90-minutes, and 180-minutes post-dose. Before each drive, participants were asked if they felt safe to drive (on real roadways, not the simulator), a yes/no question (RTD-yes/RTD-no). Venous blood was drawn at baseline and approximately 15-minutes post-dose. Cannabis use history was obtained and included whether the participant had ever driven within 2 h of use (PE-yes/PE-no) and how many days out of the past 30 they had done so (NPD).
Drives were segmented into events delineated by changes in the driving environment. Within events, standard deviation of lateral position (SDLP), average speed, and number of lane departures were calculated, and differences from baseline were modeled using mixed-effects regression. Models considered covariates of time, event, and speed, and used RTD-yes/RTD-no, PE-yes/PE-no, NPD, and their interactions as potential predictors. Conditional $R^{2}$ was used to compare the predictive ability of RTD versus change in Delta-9-THC.
Data were collected from 30 individuals who use cannabis and included cannabis use patterns, driving behaviors after use, self-reported RTD, measures of driving performance, and cannabinoid blood levels.
RTD-no predicted a 2.60 cm increase in SDLP relative to baseline (95 % CI: 0.43, 4.73, p = 0.018). Average speeds generally decreased relative to baseline, except for RTD-yes with PE-yes (+1.08 mph, 95 % CI: 0.05, 2.11). NPD predicted increased speed among RTD-yes (+0.11 mph per additional day, 95 % CI: 0.01, 0.22) and decreased speed among RTD-no (-0.06 mph per additional day, 95 % CI: −0.18, 0.32). The difference in these effects was statistically significant (p = 0.038). RTD, PE, and NPD were not significant predictors of changes in number of lane departures. For all outcomes, models using RTD achieved higher conditional $R^{2}$ than models that replaced this variable with change in Delta-9-THC. Differences were most prominent when modeling change in speed with NPD ( $R^{2} = 0.544$ with RTD vs. $R^{2} = 0.481$ with change in Delta-9-THC).
These results suggest individuals who use cannabis can somewhat self-identify when they are likely to exhibit greater degraded lateral control, although RTD does not fully explain observed degradation in performance.
Past research suggests drivers may reduce speed to compensate for recognized impairment following acute cannabis use. Our findings suggest this to be true for those who reported never having previously driven within 2 h of cannabis use or reported RTD-no, but not for those who had previously driven within 2 h of cannabis use and reported RTD-yes. This indicates compensatory behavior is not uniform and helps focus public health outreach efforts.
Motives for driving after cannabis use: A scoping review
2023, Transportation Research Part F: Traffic Psychology and Behaviour
Understanding the motives for driving after cannabis use (DACU) is crucial to improve road safety and develop effective prevention programs to reduce this behavior.
To synthesize and categorize motives for DACU reported in the scientific literature, using the Theory of Planned Behavior (Ajzen, 1991) as a basis for motive classification and conceptualization.
This scoping review followed the methodological guidelines proposed by Arksey and O’Malley, 2005, Levac et al., 2010 and the PRISMA Extension for Scoping Reviews (Tricco et al., 2018). The algorithms used to extract relevant information about the motives for DACU in the scientific literature were designed for Medline, Embase, Web of Science, and PsycINFO search engines. To be included in the review, articles had to describe motives for cannabis use as the main substance used before driving a non-commercial road motor vehicle. Any psychological justification or conscious reason was considered as a motive. A total of 30 articles were selected. A descriptive quantitative analysis and a thematic qualitative analysis were used to synthesize the results.
The studies mainly originated from the USA (k = 14), Canada (k = 6), Australia (k = 6), the UK (k = 3) and Spain (k = 1). Thirty-two motives for DACU have been classified into six themes: (1) general risk perception; (2) driving is seen as the only possible option; (3) low risk given the road or traffic conditions; (4) risk-seeking; (5) possibility to compensate for the effect of cannabis and (6) subjective norms (i.e., perception if DACU is approved or committed by others). Risk perception was by far the most frequently reported motive.
Prevention programs could greatly benefit from a better understanding of the motives for DACU. Increasing risk awareness appears to be one of the main objectives in addition to providing efficient alternative means of transport and development of prevention initiatives tailored for cannabis users.
Risk perceptions of driving under the influence of cannabis: Comparing medical and non-medical cannabis users
2023, Transportation Research Part F: Traffic Psychology and Behaviour
Reduced perception of potential harm resulting from cannabis use is associated with greater risk of driving under the influence of cannabis (DUIC). Understanding risk perceptions of DUIC among subgroups of users will positively inform targeting and content of anti-DUIC driver education and public awareness campaigns. The current study compared DUIC-related risk perceptions among individuals who use cannabis exclusively for non-medical purposes versus those who use cannabis for exclusively medical or for both medical and non-medical purposes (i.e., dual-purpose users).
Data were drawn from a regionally stratified cross-sectional general population telephone survey of adults (18 + years) in Ontario, Canada conducted in 2017. Respondents who reported past-year use of cannabis and answered questions regarding DUIC risk perceptions were selected (weighted N = 343). Modified Poisson regression models with robust standard error estimation were conducted for three attitudes: disagree that DUIC increases motor vehicle collision risk, agree that DUIC is safer than driving under the influence of alcohol (DUIA), agree that chances of being caught by police for DUIA higher than DUIC. In addition to type of cannabis user (non-medical only versus medical or dual-purpose), covariates included demographic characteristics and past-year alcohol and cannabis use frequency.
Adjusting for other covariates, regression analyses indicated that medical or dual-purpose cannabis users were 45 % more likely than non-medical users to agree that DUIC is safer than DUIA (Adjusted Prevalence Ratio = 1.45, 95 %CI = 1.10, 1.91, p = 0.007). No other differences in risk perception between medical or dual-purpose and non-medical cannabis users were found.
Although no difference between medical or dual-purpose and non-medical cannabis users was found in perceptions of collision risk associated with DUIC or risk of police enforcement, the perception that DUIC is safer than DUIA was stronger among medical or dual-purpose than non-medical users. Recognizing that the shift in public perception of DUIA as a high-risk behaviour contributed to reductions in incidence of DUIA, results of the current study support education and awareness campaigns that target medical or dual-purpose users and emphasize that, like DUIA, DUIC is also a high-risk behaviour.
Driving under the influence of cannabis risk perceptions and behaviour: A population-based study in Ontario, Canada
2021, Preventive Medicine
Citation Excerpt :
For example, several qualitative studies with respondents who self-reported engaging in DUIC while completing a remedial program for driving under the influence of alcohol (DUIA) found that many respondents did not believe that DUIC significantly increases risk of collision (Watson et al., 2019a, 2019b; Wickens et al., 2019). Some studies conducted with people who use cannabis and other drugs have corroborated this finding (Capler et al., 2017; Davey et al., 2005; Matthews et al., 2009), while other studies have identified users who believe that cannabis use improves their ability to operate a motor vehicle (Terry and Wright, 2005; Wickens et al., 2019). Prevention efforts require a broad understanding of how DUIC and its associated safety and legal risks are perceived.
Driving under the influence of cannabis (DUIC) is detrimental to road safety. Risk perception is a strong determinant of DUIC behaviour, yet little is known about the factors influencing DUIC risk perception in the general population. The objective of this study was to identify factors associated with risk perceptions of motor vehicle collision and legal consequences due to DUIC and examine whether these perceptions were associated with DUIC behaviour. Data were derived from the 2017 CAMH Monitor, a cross-sectional telephone survey of adults aged 18+ years in Ontario, Canada (n = 1813). Multivariable logistic regression analyses were performed. Approximately 90% of adults overall agreed that DUIC increases motor vehicle collision risk compared to 55% of those reporting past-year DUIC. Being male, less educated, and using cannabis at least monthly were associated with disagreeing that DUIC increases motor vehicle collision risk. Being male, young, and using cannabis at least monthly were associated with agreeing that DUIC is safer than driving under the influence of alcohol (DUIA). Being male and using cannabis less than monthly were associated with agreeing that the chances of getting caught for DUIC are higher than DUIA. Safety but not legal risk perceptions were associated with DUIC behaviour among cannabis-using drivers. Cannabis legalization provides a timely opportunity for DUIC prevention strategies. This study suggests that policymakers should target male cannabis users and highlight the safety risks of DUIC. Further research is needed to assess the effectiveness of prevention measures and the impact of cannabis legalization on DUIC perceptions and behaviour.
Interventions to Prevent Drugged Driving: A Systematic Review
2021, American Journal of Preventive Medicine
Literature suggests that cannabis legalization may increase fatal motor vehicle collisions. However, evidence on the effectiveness of interventions to prevent drugged driving is limited.
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.
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).
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.
Cannabis use and driving under the influence: Behaviors and attitudes by state-level legal sale of recreational cannabis
2020, Preventive Medicine
As states continue to legalize the sale of recreational cannabis, there is a need to study attitudes and behaviors regarding driving after cannabis use. The purpose of this study was to describe US adults' attitudes and behaviors regarding driving after cannabis use by state-level legal sale of recreational cannabis, and to determine whether these associations differ by frequency of cannabis use.
Data were collected from a national sample of 17,112 adults in the United States. Weighted adjusted prevalence ratios and 95% confidence intervals were used to compare the prevalence of behaviors and attitudes by state-level legal sale of recreational cannabis. Analyses were repeated among recent cannabis users, stratifying by cannabis use status.
Driving after cannabis use was more prevalent in legal cannabis sales states; however, so were potentially protective attitudes related to cannabis use and driving. After stratifying by frequency of use, daily/almost daily, weekly/monthly, and past 12-month users from states with legal recreational cannabis sales had significantly lower prevalence of driving after cannabis use and higher prevalence of protective attitudes compared to those from states without legal recreational sales. Risk perceptions were lower for cannabis than alcohol.
Public health messaging campaigns to reduce driving and riding after cannabis use and to improve attitudes regarding driving after cannabis use are warranted across all U.S. states, regardless of legalization status.

View all citing articles on Scopus

View full text

Short communicationSelf-reported driving behaviour and attitudes towards driving under the influence of cannabis among three different user groups in England

Abstract

Introduction

Section snippets

Methods

Participant characteristics, patterns of drug use and driving behaviour

Discussion

Acknowledgments

Forensic Science International

Accident Analysis and Prevention

The Lancet

Incidence and toxicological aspects of cannabis and ethanol detected in 1394 fatally injured drivers and pedestrians in Ontario (1982–1984)

Journal of Forensic Sciences

Short communication
Self-reported driving behaviour and attitudes towards driving under the influence of cannabis among three different user groups in England