THE EFFECTS OF MEDICAL CANNABIS USE ON DRIVING PERFORMANCE AND POLICY IMPLICATIONS FOR ROAD SAFETY
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Abstract
The objectives of this research were 1) to study and evaluate the effects of medical cannabis with varying cannabidiol-to-tetrahydrocannabinol (CBD:THC) ratios on driving performance, particularly focusing on Reaction Time and Vehicle Control, and 2) to identify the peak impairment window and duration of effect on driving performance after medical cannabis use. This research employed an experimental design, utilizing a purposive sample of 6 medical cannabis users as participants. The main instruments used were the Foot Reaction Test Device and Driving Simulation tests, with a standard threshold set at 0.75 seconds. Data analysis involved descriptive statistics and comparative analysis, including qualitative assessment to supplement the data.
The results showed that 1) participants with high THC ratios ($\ge 60\%$) had reaction times that significantly exceeded the standard threshold (0.85–1.20 seconds), resulting in a failure to brake in time and demonstrating increased errors in vehicle control. This aligns with international evidence indicating that THC directly affects the slowing of reaction time and the reduction of vehicle control ability. Conversely, participants with high or similar CBD ratios were still able to brake in time. 2) The time period with the greatest impact on driving performance was 1–3 hours post-consumption, and the impairment effects persisted even after 4–5 hours, demonstrating the long-lasting effect of THC.
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