Acute effects of ∆9-tetrahydrocannabinol (THC) on resting state brain function and their modulation by COMT genotype.
European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology June 1, 2019 Matthijs G Bossong, Hendrika H Van Hell, Chris D Schubart et al.
A single dose of THC, the main psychoactive ingredient in cannabis, increases blood flow (perfusion) in brain regions linked to the salience network—the bilateral insula, medial superior frontal cortex, and left middle orbital frontal gyrus—while decreasing connectivity between that last area and the precuneus. The perfusion increase in the left insula correlated with subjective changes in perception and relaxation. Genetic variation in the COMT Val158Met genotype modulated these effects: only Val/Met heterozygotes showed increased perfusion in the executive network after THC, suggesting that prefrontal dopamine levels influence susceptibility to cannabis's acute effects.