The Effects of Acute Cannabis With and Without Cannabidiol on Neural Reward Anticipation in Adults and Adolescents.
Adolescents may respond differently to cannabis than adults, yet no previous functional magnetic resonance imaging study has examined acute cannabis effects in this age group. In this study, 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, ages 16-17 years) and adults (n 23, 11 females, ages 26-29 years) matched on cannabis use frequency (0.5-3 daysweek) completed the Monetary Incentive Delay task during functional magnetic resonance imaging after inhaling cannabis with 0.107 mgkg Δ⁹-tetrahydrocannabinol (THC) (8 mg THC for a 75-kg person) or with THC plus 0.320 mgkg cannabidiol (THCCBD) (24 mg CBD for a 75-kg person), or placebo cannabis. We investigated reward anticipation activity with whole-brain analyses and region of interest analyses in the right and left ventral striatum, right and left anterior cingulate cortex, and right insula. THC reduced anticipation activity compared with placebo in the right (p .005, d 0.49) and left (p .003, d 0.50) ventral striatum and the right insula (p .01, d 0.42). THCCBD reduced activity compared with 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 THCCBD conditions and no significant drug by age group interaction effect, supported by Bayesian analyses. There were no significant effects in the whole-brain analyses. In weekly cannabis users, cannabis suppresses the brains anticipatory reward response to money, and CBD does not modulate this effect. Furthermore, the adolescent reward circuitry is not differentially sensitive to acute effects of cannabis on reward anticipation.