Jerusalem, Israel: Subjects engaged in the simultaneous ingestion of cannabis and alcohol experience an exponentially increased risk of motor accident compared to those who consume either substance alone, according clinical data published in the journal Accident Analysis and Prevention.
Investigators at Ben Gurion University in Israel assessed the impact of alcohol and THC cigarettes on psychomotor performance in 12 subjects on a driving simulator test. Authors reported: “Subjects were generally impaired under the influence of the drugs with the highest impairment observed after intake of the combined alcohol and THC. In terms of vehicular control, five out of the twelve subjects that participated in the study had a collision while under the influence of the combination of alcohol and THC, three had collisions after smoking THC alone, and 2 had collisions after drinking alcohol alone. None had collisions during the placebo … sessions.”
Authors concluded, “In conclusion, the results indicated that the overall effect of the combination of THC and alcohol had greater effects and caused more impairments than the two drugs separately.”
Previous studies have also reported that alcohol can exacerbate the psychomotor impairing effects of cannabis.
Separate reviews assessing the crash culpability risk of drivers under the influence of cannabis have reported a positive association between recent marijuana exposure (as typically measured by the presence of active THC in the driver’s blood) and a gradually increased, dose-dependent risk of vehicle accident. However, these studies have consistently found that this elevated risk to be below the risk presented by drivers who have consumed legal quantities of alcohol.
For more information, please contact Paul Armentano, NORML Deputy Director, at: paul@norml.org. Full text of the study, ” The effect of alcohol, THC and their combination on perceived effects, willingness to drive and performance of driving and non-driving tasks,” appears in Accident Analysis and Prevention.