Negative Urgency Mediates the Effect of Family Conflict on Cannabis Positive Expectancy: The Moderating Role of Anterior Cingulate Cortex.

Cannabis positive expectancies, favourable beliefs about cannabis effects, are a key risk factor for cannabis initiation and problematic use during adolescence. Prior research demonstrated a robust association between cannabis positive expectancies and increased use among adolescents, yet less is known about the developmental aetiology, biobehavioural mechanisms and cognitive context that contribute to these expectancies. The present study examines the intermediary role of negative urgency, a facet of impulsivity characterized by rash action under distress. Additionally, the study investigates whether anterior cingulate cortex (ACC) activation during emotional reward processing moderates this indirect effect. We conducted a longitudinal moderated mediation model with three waves of data from the Adolescent Brain and Cognitive Development (ABCD) study, analysing 6638 youths (baseline Mage = 10.1 years; 47.8% female). Family conflict at baseline predicted increased cannabis positive expectancies ΔT5T7 through increases in negative urgency at T5 (β = 0.017, p < 0.001, 95% CI 0.045, 0.069). Heightened ACC activity at T5 (anticipatory large loss), including bilateral caudal and rostral regions, intensified negative urgency's impact on cannabis positive expectancy ΔT5T7: Left caudal (β = 0.081, p < 0.001, 95% CI 0.041, 0.122), right caudal (β = 0.062, p = 0.004, 95% CI 0.020, 0.105), right rostral (β = 0.041, p = 0.026, 95% CI 0.001, 0.081) and left rostral (β = 0.052, p = 0.01, 95% CI 0.012, 0.092). This study highlights how neural activity amplifies stress-related effects on adolescent substance use expectations, suggesting emotional decision-making as a target for prevention.