In a placebo-controlled crossover trial, acute THC blunted reward-related brain activity in adults but not adolescents, and adding CBD partially offset that effect.
Neuroscience researchers, policymakers focused on youth cannabis use, clinicians working with adolescents, and parents seeking evidence on age-related cannabis effects.
THC blunted reward brain activity in adults but not in 16-17 year olds
What the researchers found
Adults showed reduced ventral striatum activation during reward anticipation after THC, while adolescents did not. The THC+CBD condition partially attenuated this blunting in adults, suggesting CBD may modulate THC effects on reward circuitry.
Why it matters
The developing adolescent brain may process cannabis differently than the adult brain. Understanding these age-dependent effects on reward circuits is critical for assessing the unique risks cannabis poses to younger users.
The numbers in context
47 participants (24 adolescents, 23 adults). THC dose: 0.107 mg/kg (about 8 mg for 75 kg person). CBD dose: 0.320 mg/kg. Three conditions: THC only, THC+CBD, placebo. Adults showed reduced ventral striatum activation under THC; adolescents did not.
How the study worked
Double-blind, placebo-controlled, randomized crossover design. 47 participants (24 adolescents ages 16-17, 23 adults ages 26-29) matched on cannabis use frequency completed the Monetary Incentive Delay task during fMRI after inhaling THC alone, THC+CBD, or placebo.
What this study cannot tell us
Moderate sample size (47 total). Participants were existing cannabis users (0.5-3 days/week), so findings may not generalize to naive users. Single-session design cannot address repeated exposure effects. THC dose was relatively low.
How to read the evidence
Randomized, placebo-controlled crossover design with neuroimaging is rigorous. Moderate sample size and single-session design are limitations.
When this study was published
Published 2022.
The bigger picture
Reward system development is a key feature of adolescence. If THC affects reward processing differently in teens versus adults, age-specific risk communication and policy approaches may be warranted rather than one-size-fits-all messaging.
Questions still open
- Does the lack of reward blunting in adolescents reflect resilience or a different vulnerability pattern? Would higher or repeated doses produce different age-dependent effects?
Common questions
Does this mean cannabis is safer for teens than adults?
What does reward anticipation mean in brain imaging?
Read the original research
The Effects of Acute Cannabis With and Without Cannabidiol on Neural Reward Anticipation in Adults and Adolescents.
Biological psychiatry. Cognitive neuroscience and neuroimaging, 8(2), 219-229
Citation
Skumlien, Martine; Freeman, Tom P; Hall, Daniel; Mokrysz, Claire; Wall, Matthew B; Ofori, Shelan; Petrilli, Kat; Trinci, Katie; Borissova, Anna; Fernandez-Vinson, Natalia; Langley, Christelle; Sahakian, Barbara J; Curran, H Valerie; Lawn, Will. (2023). The Effects of Acute Cannabis With and Without Cannabidiol on Neural Reward Anticipation in Adults and Adolescents.. Biological psychiatry. Cognitive neuroscience and neuroimaging, 8(2), 219-229. https://doi.org/10.1016/j.bpsc.2022.10.004
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