A cannabis product with as much CBD as THC can still affect lane tracking. Arkell and colleagues tested this in 14 healthy volunteers with a history of light cannabis use. Each volunteer completed sessions with THC-dominant flower, flower with equivalent THC and CBD, and placebo. The two active products contained the same percentage of THC in the plant material.
Both active products increased lane weaving during a car-following task, while several other driving measures showed little change. Lane weaving reflects how consistently the driver held a lateral position. The study therefore identified a change in a specific part of driving performance under a controlled protocol.
The researchers also reported a higher peak plasma THC concentration with the balanced product. Equal THC content in the starting material did not translate into equal observed peaks. The small sample, the particular formulations and the simulator task define the scope of the result. An interpretation for another exposure would need information about the product and the actual driving conditions.