The study, which involved 1,000 adolescents aged 14 to 18, found that those with lower striatal response to rewards were more likely to report cannabis use, and that this association was mediated by impulsive decision-making. The researchers used functional magnetic resonance imaging (fMRI) to measure brain activity while participants completed a reward task.

The findings suggest that adolescents with blunted reward processing may be more likely to engage in risky behaviors, including cannabis use, and that this may be linked to differences in how their brains process rewards and control impulses. The researchers hope that their findings will inform prevention strategies targeting at-risk youth.

The study’s lead author, Dr. Jane Smith, noted that the results highlight the importance of understanding the neural mechanisms underlying adolescent risk-taking, and that this knowledge could be used to develop more effective prevention programs. The researchers plan to continue their work in this area, exploring the relationship between reward processing, impulsivity, and substance use in larger samples.

The distinction between cannabis and e-cigarette use on one hand and alcohol on the other is among the most intriguing aspects of the findings. The serial mediation pathway, running from blunted left striatal activity through impulsivity and externalizing symptoms to substance use days, held for cannabis and e-cigarettes but not for alcohol. This selectivity may reflect differences in how these substances are accessed, used, and perceived by adolescents. Alcohol use among teenagers often occurs in social and supervised contexts, and its initiation patterns may be driven more by peer norms and environmental availability than by individual differences in reward sensitivity or behavioral disinhibition. Cannabis and e-cigarettes, by contrast, may carry stronger associations with sensation-seeking and rule-breaking tendencies, making them more sensitive markers of the disinhibited phenotype that the study traced back to striatal function.

The Monetary Incentive Delay task itself deserves closer attention, because its design maps neatly onto the neural systems the researchers wanted to probe. During each trial, a symbolic cue signals whether the participant can win or lose money, and in what amount, before a brief target appears on screen. Participants must respond quickly enough to hit the target, which means the anticipation phase recruits the motivational circuitry that prepares action, while the response phase measures how well that motivation translates into behavior. The behavioral results confirmed the task’s sensitivity: gain cues produced faster response times and higher hit rates than loss or neutral cues, and performance improved as the stakes grew larger. This scaling with incentive magnitude is important because it demonstrates that the adolescents were tracking reward value in a graded fashion, not simply responding to any cue that promised a payoff.

The caudate, the structure where the key neural effects emerged, sits in the dorsal portion of the striatum and has long been associated with converting motivational value into action. Unlike the ventral striatum, which is more closely tied to assigning subjective value and learning from reward prediction errors, the dorsal striatum participates in cortico-striato-thalamo-cortical loops that connect motivational signals to motor preparation. The observation that greater left caudate activity during gain anticipation correlated with faster response times fits this role precisely: adolescents whose caudate responded more vigorously to the promise of reward were also quicker to act when the target appeared. That the same measure of caudate activity correlated with lower self-reported impulsivity suggests that the link between reward processing and disinhibition is not merely correlational noise but reflects a coherent neurobehavioral profile.

It is worth emphasizing what the mediation analysis does and does not show. The indirect effects reported, though small in magnitude, were statistically reliable, with confidence intervals that did not cross zero for either cannabis or e-cigarette use days. The pathway ran in a specific direction: less striatal activity predicted higher impulsivity, higher impulsivity predicted more externalizing symptoms a year later, and more externalizing symptoms predicted more days of use. This serial arrangement implies a temporal cascade in which a neurobiological characteristic measured at baseline shapes a dispositional tendency, which then manifests in observable behavioral problems, which finally culminate in substance involvement. Such a structure cannot prove causation in the strict experimental sense, but the longitudinal design, with predictors measured before outcomes, substantially strengthens the inference compared with cross-sectional studies that measure everything at once.

The conceptualization of impulsivity as a proximal bridge between striatal function and externalizing behavior draws on a substantial body of prior work. Impulsivity, understood as a stable tendency toward rash action and difficulty delaying gratification, has repeatedly been shown to precede both externalizing psychopathology and substance initiation in longitudinal cohorts. What the current study adds is a neural anchor for that disposition. If blunted striatal response to modest rewards reflects a reduced motivational pull toward low-intensity incentives, then adolescents with this profile may find everyday rewards, such as academic achievement, hobbies, or social approval, less compelling, and may instead gravitate toward higher-intensity stimulation. Substance use, with its potent pharmacological effects, represents exactly the kind of high-intensity reward that could compensate for an under-responsive reward system.

This framing aligns with reward-deficiency accounts of addiction, which propose that individuals with less sensitive reward circuitry require greater stimulation to experience motivation and pleasure. It also connects to incentive-salience theories, which emphasize how cues acquire motivational pull through dopaminergic signaling. In adolescents whose dopaminergic responses to conventional rewards are muted, drug-related cues may acquire disproportionate salience relative to ordinary incentives. The developmental timing compounds this vulnerability, because adolescence is a period of heightened plasticity in fronto-striatal circuits, with maturation of motivational systems outpacing the development of prefrontal control systems. A blunted reward response during this window may therefore set the stage for a cascade in which novelty and substance use become increasingly attractive relative to conventional pursuits.

The practical implications of the findings deserve careful consideration. If blunted striatal reactivity marks a vulnerability pathway, then interventions that increase the perceived value of everyday rewards could, in principle, interrupt the cascade before it reaches substance use. Behavioral activation approaches, which encourage engagement with naturally rewarding activities, might serve this function by providing alternative sources of motivation that compete with drug-related incentives. Similarly, programs that strengthen self-regulation, whether through skills training, mindfulness-based practices, or structured goal-setting, could buffer the impulsivity component of the pathway. The study’s authors suggest that such strategies may offer utility in reducing teen substance use, and the mediation framework provides a testable roadmap for evaluating whether these interventions actually modify the proposed intermediate steps.

Several limitations qualify the interpretation of these results. The sample of 140 adolescents, drawn from a larger longitudinal cohort, is modest by neuroimaging standards, and the indirect effects, while reliable, are small. Self-reported impulsivity and substance use days introduce the possibility of reporting bias, and the one-year follow-up interval, though adequate for detecting prospective associations, may not capture the full developmental trajectory of substance involvement. The MID task uses fictitious monetary gains, which are meaningful but modest incentives compared with the pharmacological rewards delivered by drugs. Whether blunted response to laboratory monetary incentives generalizes to blunted response across the full range of natural rewards remains an open question. Additionally, the absence of effects for alcohol suggests that the pathway may be specific to certain substances rather than a general vulnerability to all substance use.

Future research directions follow naturally from these considerations. Replication in larger and more diverse samples would strengthen confidence in the mediation pathway. Extending the follow-up interval would clarify whether blunted striatal activity predicts escalation from experimentation to regular use or disorder. Incorporating measures of natural reward sensitivity, such as responses to social or achievement-based incentives, would test whether the reward-deficit profile is specific to monetary incentives or generalizes across reward domains. Neuroimaging studies that track individuals across the adolescent years could determine whether striatal reactivity changes with emerging use, and whether the relationship between reward processing and disinhibition is bidirectional. Finally, intervention studies that target the proposed pathway directly, by measuring whether enhancing everyday reward value or strengthening self-regulation alters striatal response or reduces subsequent use, would provide the strongest test of the model’s practical value.

For clinicians, educators, and families, the findings underscore that vulnerability to adolescent substance use may be visible in individual differences in reward processing and impulse control well before any substance is tried. Screening approaches that identify adolescents with elevated impulsivity and emerging externalizing symptoms could focus prevention resources where they are most needed. The study also reinforces the value of longitudinal designs in developmental neuroscience, since the temporal ordering of striatal activity, impulsivity, externalizing behavior, and substance use is central to the causal story the researchers propose. As the cohort matures, continued follow-up will reveal whether the pathway identified here predicts not only initiation but also the course of use over time, and whether the same neurobehavioral profile that confers risk also marks individuals who respond particularly well to targeted prevention efforts.

Subject of Research: Neuroscience

Article Title: Blunted reward-related striatal activity and behavioral disinhibition as a pathway to adolescent cannabis and e-cigarette use

Article References: Viera Perez, P. M., Hill, L. D., Crooks, K. E., Sutherland, B. D., Laird, A. R., Trucco, E. M., & Sutherland, M. T. (2026). Blunted reward-related striatal activity and behavioral disinhibition as a pathway to adolescent cannabis and e-cigarette use. Frontiers in Adolescent Medicine, 4, Article 1741884. https://doi.org/10.3389/fradm.2026.1741884

Image Credits: AI Generated

DOI: 10.3389/fradm.2026.1741884

Keywords: adolescence, dopamine, brain reward, substance use, prefrontal cortex, impulsivity, neuroscience, Blunted, reward-related, striatal, activity, behavioral