People Against Drink/Drug Driving

Cannabis & Driving – Research continues to Affirm the Risks & Dangers of THC (Cannabis) Use and Driving (Labelling it ‘Medicinal’ doesn’t reduce risks)

The effects of cannabis and alcohol on driving performance and driver behaviour: a systematic  review and meta-analysis
Conclusions: This meta-analysis indicates that cannabis, like alcohol, impairs driving, and
the combination of the two drugs is more detrimental to driving performance than either
in isolation. (Source: https://onlinelibrary.wiley.com/doi/10.1111/add.15770 )

Simultaneous Alcohol/Cannabis Use and Driving Under the Influence in the U.S.
Conclusions: Overall, 2 in 5 drivers who used alcohol and cannabis reported driving under the influence of alcohol and/or cannabis. People reporting simultaneous alcohol/cannabis use were more likely to report cannabis-related driving under the influence. Prevention strategies should target individuals reporting simultaneous alcohol/cannabis use to reduce the occurrence of driving under the influence.  (Source: Am J Prev Med 2022;62(5):661−669. © 2021 American Journal of Preventive Medicine. Published by Elsevier Inc.)

Effects of Combining Alcohol and Cannabis on Driving, Breath Alcohol Level, Blood THC, Cognition, and Subjective Effects: A Narrative Review
Conclusions: Given the prevalence of co-use of alcohol and cannabis, it is of interest to determine the effects of combinations of these drugs on driving. In the present review, we summarize the findings of studies that investigated the use of combinations of these drugs on driving. In general, it appears that combinations of alcohol and cannabis increase measurements of lane deviations and reaction time.
Findings of the effects of these drugs on speed are mixed. Despite evidence for additive effects of these drugs on driving, findings are inconclusive as to whether there are additive effects of cannabis and alcohol on blood THC or BrAC/BAC. In addition, human laboratory studies assessing neurocognitive task performance under the influence of alcohol and cannabis have found that divided attention task performance is particularly sensitive to the combination of the two drugs compared to either drug alone, though the evidence for other cognitive task performance is mixed. Converging evidence from studies of the effects of alcohol and cannabis co-use on cognition and subjective effects also points to an additive effect in some (Source: A.P.A. Experimental and Clinical Psychopharmacology 2022, Vol. 30, No. 6, 1036–1049 https://doi.org/10.1037/pha0000533 )

Driving Performance and Cannabis Users’ Perception of Safety A Randomized Clinical Trial
Conclusions: Smoking cannabis ad libitum by regular users resulted in simulated driving decrements. However, when experienced users control their own intake, driving impairment cannot be inferred based on THC content of the cigarette, behavioral tolerance, or THC blood concentrations. Participant’s increasing willingness to drive at 1 hour 30 minutes may indicate a false sense of driving safety. Worse driving performance is evident for several hours postsmoking in many users but appears to resolve by 4 hours 30 minutes in most individuals. (Source: JAMA Psychiatry. doi:10.1001/jamapsychiatry.2021.4037 2022)

Changes in Traffic Crash Rates After Legalization of Marijuana: Results by Crash Severity
Conclusions: The estimated increases in injury and fatal crash rates after recreational marijuana legalization are consistent with earlier studies, but the effects varied across states. Because this is an early look at the time trends, researchers and policymakers need to continue monitoring the data. (Source:  Journal Studies Alcohol & Drugs https://www.jsad.com/doi/10.15288/jsad.2022.83.494 2021)

Correlates of driving after cannabis use in high school students
Conclusions: We found several correlates associated with driving under the influence of cannabis in adolescents, including probable cannabis dependence, various risky driving behaviors, pro-legalization attitudes, and low perceptions of risk associated with regular cannabis use. Efforts to reduce driving under the influence of cannabis should focus on targeting students who engage in a wide variety of risky behaviors, as these students may be at the highest risk of driving after cannabis use. In addition, interventions may benefit by addressing students’ relaxed attitudes towards cannabis use. (Source: Science Direct https://doi.org/10.1016/j.ypmed.2021.106667 2021)

For more see Submission: Medicinal Cannabis & Driving – Is it an Issue?

‘A Seven Fold Increase in DUID’ (Driving Under Influence of Drugs) It is interesting to note that whilst there has a been a slight decline in Alcohol associated incidents, cannabis has ‘filled the gap’ with an increased involvement in impaired driving issues. What is concerning is that the extent of cannabis influence on driving harms is most likely under-reported, as once medical examiners detect significant alcohol content in victims they often end their investigation as to the ‘drug of impairment’ at that point.

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Key Points

1. Driving under the influence of cannabis has been identified as a public health concern as medical and recreational cannabis availability increases in some countries.
2. A recent randomized clinical trial found similar levels of acute driving impairment with THC-dominant cannabis and with a combination of THC-CBD equivalent cannabis using on-road driving tests that provided real-world conditions; however, CBD-dominant cannabis did not produce significant cognitive or psychomotor impairment compared with placebo in this trial.
3. Media coverage of this study conveyed the findings as CBD-dominant cannabis not causing driving impairment while THC-dominant cannabis does, with the latter lasting up to 4 h post-dose.
4. It is recommended that clinicians counsel about the risks of driving impairment when patients disclose use of cannabis products containing THC.

Complete Research PDF

Also See
Cannabis use altering key functions like three-dimensional vision
“Medicinal” Cannabis & Driving – is it an Issue?

Journal of Studies on Alcohol and Drugs, 83(4), 494–501 (2022).

Abstract

Objective: The objective of this study was to estimate the effects of marijuana legalization and the subsequent onset of retail sales on injury and fatal traffic crash rates in the United States during the period 2009–2019.

Method: State-by-state quarterly crash rates per mile of travel were modeled as a function of time, unemployment rate, maximum posted speed limit, seat belt use rate, alcohol use rate, percent of miles driven on rural roads, and indicators of legalized recreational marijuana use and sales.

Results: Legalization of the recreational use of marijuana was associated with a 6.5% increase in injury crash rates and a 2.3% increase in fatal crash rates, but the subsequent onset of retail marijuana sales did not elicit additional substantial changes. Thus, the combined effect of legalization and retail sales was a 5.8% increase in injury crash rates and a 4.1% increase in fatal crash rates. Across states, the effects on injury crash rates ranged from a 7% decrease to an 18% increase. The effects on fatal crash rates ranged from a 10% decrease to a 4% increase.

Conclusions: The estimated increases in injury and fatal crash rates after recreational marijuana legalization are consistent with earlier studies, but the effects varied across states. Because this is an early look at the time trends, researchers and policymakers need to continue monitoring the data.

For complete research

Alcohol interlocks significantly reduce drink driving while interlocks are active and (to a modest extent) following their removal.

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