first of its kind long term b study b at virgin

First-of-its-kind long-term study at Virginia Tech shares how cannabis use can affect driving

✦ New
CED Clinical Relevance
#62 Notable Clinical Interest
Emerging findings or policy developments worth monitoring closely.
ResearchSafetyTHCPolicyDosing
Why This Matters
Patients who use cannabis medicinally need to understand that subjective feelings of being “fine to drive” can diverge significantly from actual measured driving performance, particularly in the hours following consumption.
Clinical Summary

The relationship between cannabis consumption and driving performance is genuinely complex, because THC impairment does not follow the same linear dose-response curve that alcohol does, and standard roadside testing fails to capture the nuanced ways cannabis affects reaction time, lane tracking, and divided attention. Tolerance, consumption method, cannabinoid ratios, and individual pharmacokinetics all influence how significantly any given person is impaired behind the wheel. Long-term naturalistic driving studies are among the most rigorous methodologies available for understanding real-world behavior rather than controlled laboratory conditions that may not reflect actual driving environments.

Dr. Caplan’s Take
“We have been making driving policy around cannabis using alcohol-based frameworks and cross-sectional snapshots, and longitudinal naturalistic data is long overdue for actually getting this right.”
Clinical Perspective

🔬 This Virginia Tech Transportation Institute study addresses a critical gap in our understanding of cannabis and driving safety by using real-world, longitudinal data rather than relying solely on simulator-based research.

💊 As cannabis becomes legal in more jurisdictions, clinicians need robust evidence to counsel patients on impairment duration, individual variability in driving ability, and the distinction between acute intoxication and residual cannabinoid detection.

💊 Understanding how different cannabis consumption methods, THC/CBD ratios, and individual tolerance levels affect actual driving performance will help us provide more nuanced, patient-centered guidance beyond blanket recommendations.

🔬 This research underscores the importance of distinguishing between cannabis use and cannabis-impaired driving, allowing us to have more sophisticated conversations with patients about their specific risk profiles and safer use practices.

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