Computational risk profiles of impulsive decision-making for substance use disorders: similarities and differences between stimulants and opioids

Objective: Impulsive decision-making is strongly associated with substance use disorders (SUD). We used a battery of decision-making tasks to investigate similarities and differences in decision-making patterns between stimulant (amphetamine) and opioid (heroin) users. Additionally, we explored whether impulsive decision-making could serve as a potential endophenotype for addiction using a sibling comparison design.Methods: Participants included individuals with “pure” SUD (opioids: N=157, stimulants: N=140), healthy controls (N=240), and unaffected siblings of opioid (N=67) and stimulant (N=52) users. We used the Iowa Gambling Task (IGT), Cambridge Gambling Task (CGT), Balloon Analogue Risk Task (BART), and Delayed Reward Discounting Task (DRDT) to measure decision-making. Task behaviors were analyzed using hierarchical Bayesian modeling and we compared the group-level decision-making computational parameters. Results: Both drug groups had higher temporal discounting of rewards on the DRDT and CGT; tended to prioritize their past choices over past rewards on the IGT, indicated by high perseverance weight and low outcome frequency weight; and weighed more recent choices over distant ones on the IGT. These patterns were also observed in their unaffected siblings, indicating potential endophenotypes. Opioid users and their siblings displayed reduced loss sensitivity on the IGT and CGT, indicating that this might be an endophenotype specific to opioid addiction. Conclusions: This study provides insights into common and specific decision-making vulnerabilities of different types of drug addictions, some of which were observed in unaffected siblings, suggesting potential endophenotypes. Such computational decision-making profiles could increase the precision of neurocognitive assessment and aid in developing targeted intervention strategies.