New research from Johns Hopkins Bloomberg School of Public Health quantifies a startling interaction between cannabis and alcohol: drivers consuming both substances demonstrated impairment levels 2.8 times greater than those using alcohol alone. The controlled driving simulation study measured composite impairment scores across multiple driving scenarios, with cannabis-alcohol combinations scoring 2.8 compared to alcohol-only at 2.0. Of particular concern to public health and law enforcement officials, conventional field sobriety tests failed to reliably detect cannabis-related impairment, creating a critical gap in roadside assessment capabilities. This detection failure represents a significant challenge for traffic safety enforcement as cannabis products become increasingly available. The research, published in Drug and Alcohol Dependence, underscores the need for updated assessment protocols and public education regarding polysubstance use and driving safety. Read the full article on GMJ Newsroom.
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