Daily Cannabis Users Showed Little Driving Impairment After Using High-Potency Products

Occasional flower users had a significant increase in lane departures after cannabis use (0.16/min at baseline to 0.47/min 30 minutes post-use). Daily flower and daily concentrate users showed little to no change in lane departures or speed. All cannabis-using groups maintained or slightly decreased speed post-use, while controls slightly increased speed. Overall driving changes were relatively small across all groups.

118 participants completed three 20-minute simulated drives: baseline, 30 minutes post-use, and 90 minutes post-use. 89 inhaled their own cannabis products (flower or concentrates) for up to 15 minutes, while 29 controls completed the protocol without using cannabis. Groups were divided by use frequency and product type.

Most cannabis-driving research uses low-potency products that do not reflect what is actually sold in legal markets. This study used participants' own products (including high-potency concentrates) and found that tolerance plays a major role: daily users showed little impairment even with stronger products.

The finding that daily users show minimal driving impairment even with high-potency products complicates impaired-driving policy. It suggests tolerance significantly affects driving risk, meaning a THC blood level that impairs an occasional user may have little effect on a daily user.

Simulated driving may not capture all real-world driving demands, self-selected participants using their own products creates dosing variability, no THC blood levels reported in abstract, within-subjects design but unequal group sizes, controlled environment differs from real driving conditions