An fMRI study of 20 near-daily cannabis users found that brain regions encoding subjective value responded normally to cannabis rewards but showed disrupted value encoding for food rewards, despite equivalent choice behavior for both.
Addiction neuroscientists, clinical researchers studying cannabis use disorder, and neuroeconomists.
vmPFC value encoding was stronger for cannabis than food rewards
What the researchers found
Subjective value signals for cannabis appeared in vmPFC, ventral striatum, and dorsal PCC as expected. Value encoding in vmPFC was stronger for cannabis than snacks. For snack rewards, expected value signals were absent. Cannabis and snack cues differentially modulated value encoding in the dorsal PCC. Choice behavior was equivalent between reward types despite the neural differences.
Why it matters
This study provides neural evidence for a key addiction theory: that problematic substance use involves not just enhanced drug valuation but degraded valuation of non-drug rewards. The behavioral equivalence masking neural differences suggests standard behavioral measures may miss this dysfunction.
The numbers in context
20 analyzed; near-daily use (4+ days/week); value signals in vmPFC, ventral striatum, dPCC for cannabis but not snacks; vmPFC encoding stronger for cannabis vs. snacks.
How the study worked
Inpatient crossover design with 21 non-treatment-seeking near-daily cannabis users (20 analyzed). Four conditions crossing cue type (neutral/drug or neutral/snack) with reward type (cannabis/snack). fMRI during economic choice task choosing between 0-6 cannabis puffs or snacks vs. fixed monetary amounts.
What this study cannot tell us
Small sample (n=20). Only 1 female participant. Non-treatment-seeking users. Cross-sectional design cannot determine if neural differences preceded cannabis use. Snacks may not adequately represent all non-drug rewards.
How to read the evidence
Novel fMRI design with ecological validity (real cannabis rewards), but very small, predominantly male sample limits generalizability.
When this study was published
2025 fMRI study of neural value encoding in near-daily cannabis users.
The bigger picture
The dissociation between intact cannabis value signals and disrupted food value signals supports theories that addiction involves a narrowing of reward valuation rather than simple overvaluation of the drug. This has implications for treatment targets.
Questions still open
- Does disrupted non-drug value encoding recover with cannabis abstinence?
- Could restoring non-drug reward sensitivity be a treatment target?
Common questions
Does cannabis change how the brain values rewards?
Do cannabis users behave differently when choosing?
Read the original research
Value signals guiding choices for cannabis versus non-drug rewards in people who use cannabis near-daily.
Psychopharmacology, 242(4), 681-691
Citation
Lawn, Will; Hao, Xuejun; Konova, Anna B; Haney, Margaret; Cooper, Ziva D; Van Dam, Nicholas; Glimcher, Paul; Bedi, Gillinder. (2025). Value signals guiding choices for cannabis versus non-drug rewards in people who use cannabis near-daily.. Psychopharmacology, 242(4), 681-691. https://doi.org/10.1007/s00213-025-06746-6
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