AUTHOR=Preuss Ulrich W., Huestis Marilyn A., Schneider Miriam, Hermann Derik, Lutz Beat, Hasan Alkomiet, Kambeitz Joseph, Wong Jessica W. M., Hoch Eva TITLE=Cannabis Use and Car Crashes: A Review JOURNAL=Frontiers in Psychiatry VOLUME=12 YEAR=2021 URL=https://www.frontiersin.org/articles/10.3389/fpsyt.2021.643315 DOI=10.3389/fpsyt.2021.643315 ISSN=1664-0640 ABSTRACT=In this review, state-of-the-art evidence on the relationship between cannabis use, traffic crash risks, and driving safety were analyzed. Systematic reviews, meta-analyses, and other relevant papers published within the last decade were systematically searched and synthesized. Findings show that meta-analyses and culpability studies consistently indicate a slightly but significantly increased risk of crashes after acute cannabis use. These risks vary across included study type, crash severity, and method of substance application and measurement. Some studies show a significant correlation between high THC blood concentrations and car crash risk. Most studies do not support this relationship at lower THC concentrations. However, no scientifically supported clear cut-off concentration can be derived from these results. Further research is needed to determine dose-response effects on driving skills combined with measures of neuropsychological functioning related to driving skills and crash risk.