The acute and residual effects of cannabis on driving performance, cognition, attention and fatigue

A major health concern about cannabis use is the increased risk of traffic accidents if users drive while intoxicated [1,2]. The relationship between delta-9 tetrahydrocannabinol (THC) concentrations in blood and actual driving impairment or crash risk is, however, somewhat unclear [3]. Less is known about cannabis impairment during the residual phase of intoxication except that users often report fatigue and inattention. This study was therefore designed, in part, to help define performance impairment as a function of the amount of active THC in blood and saliva. Impairment was measured during the acute and residual phases of consumption across several performance and fatigue-related variables