Adolescents may respond differently to cannabis than adults, yet no functional magnetic resonance imaging (fMRI) study has examined acute cannabis effects in this age-group. We investigated the neural correlates of reward anticipation after acute exposure to cannabis in adolescents and adults.
This was a double-blind, placebo-controlled, randomized, crossover experiment. Forty-seven adolescents (n=24, 12 females, 16-17 years) and adults (n=23, 11 females, 26-29 years), matched on cannabis use frequency (0.5-3 days/week), completed the Monetary Incentive Delay task during fMRI after inhaled cannabis with 0.107 mg/kg THC (‘THC’) (8 mg THC for a 75 kg person) or THC plus 0.320 mg/kg CBD (‘THC+CBD’) (24 mg CBD for a 75 kg person), or placebo cannabis (‘PLA’). We investigated reward anticipation activity with whole-brain analyses and region of interest (ROI) analyses in right and left ventral striatum, right and left anterior cingulate cortex, and right insula.
THC reduced anticipation activity compared to placebo in the right (P=.005, d=0.49) and left (P=.003, d=0.50) ventral striatum, and right insula (P=.01, d=0.42). THC+CBD reduced activity compared to placebo in the right ventral striatum (P=.01, d=0.41) and right insula (P=.002, d=0.49). There were no differences between ‘THC’ and ‘THC+CBD’ and no significant Drug*Age-Group effect, supported by Bayesian analyses. There were no significant effects in the whole-brain analyses.
In weekly cannabis users, cannabis suppresses the brain’s anticipatory reward response to money and CBD does not moderate this effect. Furthermore, the adolescent reward circuitry is not differentially sensitive to acute effects of cannabis on reward anticipation.
|Journal||Biological Psychiatry: Cognitive Neuroscience and Neuroimaging|
|Early online date||28 Oct 2022|
|Publication status||E-pub ahead of print - 28 Oct 2022|