How common is driving under the influence of marijuana? Of driving under the influence of alcohol? Of driving under the influence of both at the same time?
To find out, researchers studied self-reports of drivers age 16 to 25. The data came from the National Survey on Drug Use and Health. The period was 12 years. That survey is conducted by a federal agency, SAMHSA.
The incidence of driving under the influence of alcohol alone dropped 59%. That was among those age 16-20. It fell 38% among those age 21-25.
Driving under the influence of both alcohol and marijuana dropped 39% among those age 16-20. It declined 52% among those age 21-25.
The prevalence of driving under the influence of marijuana alone fell 18%. But only among drivers age 16-20.
Over 12 years, the incidence of driving under the influence of marijuana, alcohol and both generally dropped greatly. See figures 1 and 2. For larger views, click on images.
Resources: driving under the influence of marijuana, alcohol, and both.
Surprising Effects of Drugs on Driving Safety. (They can improve safety.)
Bedard, M., et al. The impact of cannabis on driving. Canad J Pub Health, 98(1), 6-11.
Berning, A., et al. Results of the 2014 “2013 National Roadside Survey of Alcohol and Drug Use by Drivers. Rep No. DOT HS 812 118. Wash: NHTSA.
Hanson, D. Effects of Substances on Driving. In: Miller, P. (Ed.) Principles of Addiction. Amsterdam: Elsevier.
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Azofeifa, A., et al. Driving under the influence of alcohol, marijuana, and alcohol and marijuana combined among persons aged 16-25 Years. Morbid and Mort Weekly Rep, 64(48), 1325-9.