An April 2024 cross-sectional study of visits to American Emergency Departments in Denver Colorado, Portland Oregon and Sacramento California, ‘Risk of motor vehicle collision associated with cannabis and alcohol use among patients presenting for emergency care’, evidenced that cannabis alone was not associated with higher odds of motor vehicle collision (MVC), while acute alcohol use alone and combined use of alcohol and cannabis were both independently associated with higher odds of MVC.
For cannabis use, higher levels were not associated with higher odds for MVC, with or without co-use of alcohol; in fact, high self-reported acute cannabis use was associated with lower odds of MVC! Researchers completed a case-crossover analysis which showed that alcohol use alone or in combination with cannabis was associated with higher odds of MVC, while cannabis use alone was again associated with decreased odds of MVC.
Results: Cannabis use alone was associated with decreased odds of motor vehicle collision (MVC)
Alcohol use alone or in conjunction with cannabis was consistently associated with higher odds for MVC. However, the relationship between measured levels of cannabis and MVC was not as clear. Emphasis on actual driving behaviours and clinical signs of impairment to determine driving under the influence has the strongest rationale.