9th February 2022
By Roland Sebestyén

In the US, more than half of citizens now live in a state with a legal, regulated recreational cannabis market, with additional states having some kind of decriminalisation policy. Despite laws still being in place to prevent driving after alcohol and cannabis consumption, a recent study shows that a significant number of people are happy to drive after consuming the intoxicants.

Researchers of the study, published in the American Journal of Preventive Medicine, assessed drivers with past year cannabis use and concluded that 40% reported driving under the influence of either or both substances.

Drivers aged 16 years or older who reported any past-year alcohol and cannabis use in the National Survey on Drug Use and Health (2016-2019) were included with a final study sample of 34,514.

The outcome was reporting any past-year driving under the influence of alcohol-only (DUI-A), cannabis-only (DUI-C), alcohol and cannabis (DUI-A+C), or no DUI.

The results are shocking: between 2016-2019, 42% of drivers with past-year alcohol and cannabis use reported any past-year DUI (8% DUI-A, 20% DUI-C, 14% DUI-A+C).

Lead author Priscila Dib Gonçalves in the Department of Epidemiology at Columbia Mailman School said: “Alcohol and cannabis are two of the most common substances involved in impaired driving and motor vehicle crashes in the U.S.

“Examining the effect of simultaneous alcohol and cannabis use on self-report driving under the influence (DUI) of alcohol-only, cannabis-only, and both substances using a nationally representative sample could contribute to better understanding the impact in adolescents and adults.”

Simultaneous use was also associated with 2.88 times higher odds of driving under the influence of cannabis, and 3.51 times higher odds of driving under the influence of both alcohol and cannabis.

Pia Mauro, PhD, assistant professor of epidemiology, and senior author added: “In the context of increasing daily cannabis use among adults, our findings connecting daily cannabis use and DUI raises public health concerns.

“Population changes in cannabis use frequency that may be associated with health hazards, including daily use, need to be continuously monitored.”

Earlier research has suggested that the combined consumption of cannabis and alcohol increases driving impairment. This may lead to an uptick in the risk of fatal traffic accidents – more than either substance individually.

A recent study revealed that, while cannabis users may present an increased willingness to drive at 90 minutes following consumption, this may represent a false sense of security regarding driving safety.

It is reported that the perception of driving impairment decreased at 1 hour 30 minutes, despite no objective improvement in driving.

The researchers concluded that after the 4 and half hour mark did they find no differences in driving scores.

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