Tolerance and cross-tolerance to neurocognitive effects of THC and alcohol in heavy cannabis users
Psychopharmacology October 30, 2010 Johannes G. Ramaekers, Eef L. Theunissen, Marjolein de Brouwer et al. 168 citations
Heavy cannabis users develop tolerance to the impairing effects of THC on neurocognitive tasks, but they do not develop cross-tolerance to the impairing effects of alcohol. In a double-blind study, 21 heavy cannabis users received alcohol at three levels (targeting blood alcohol concentrations of 0, 0.5, and 0.7 mg/ml) and smoked a THC cigarette (400 μg/kg) 3 hours after drinking began. Alcohol alone impaired performance on tests of perceptual motor control, divided attention, and motor inhibition, while THC alone generally did not affect performance. However, combining THC and alcohol produced greater impairments in divided attention than alcohol alone, indicating that alcohol can potentiate THC effects in tolerant users.