Neurophysiological functioning of occasional and heavy cannabis users during THC intoxication

Abstract Rationale: Experienced cannabis users demonstrate tolerance to some of the impairing acute effects of cannabis. Objectives: The present study investigates whether event-related potentials (ERPs) differ between occasional and heavy cannabis users after acute Δ9-tetrahydrocannabinol (THC) administration, as a result of tolerance. Methods: Twelve occasional and 12 heavy cannabis users participated in a double-blind, placebo-controlled, crossover study. On two separate days, they smoked a joint containing 0 or 500 μg/kg body weight THC. ERPs were measured while subjects performed a