부산대학교 도서관

Rationale:There is converging evidence for impairments in decision-making in chronic substance users. In the light of findings that substance abuse is associated with disruptions of the functioning of the striato–thalamo–orbitofrontal circuits, it has been suggested that decision-making impairments are linked to frontal lobe dysfunction. We sought to investigate this possibility using functional neuroimaging.Methods:Decision-making was investigated using the Cambridge Risk Task during H215O PET scans. A specific feature of the Risk Task is the decisional conflict between an unlikely high reward option and a likely low reward option. Four groups, each consisting of 15 participants, were compared: chronic amphetamine users, chronic opiate users, ex-drug users who had been long-term amphetamine/opiate users but are abstinent from all drugs of abuse for at least 1 year and healthy matched controls without a drug-taking history.Results:During decision-making, control participants showed relatively greater activation in the right dorsolateral prefrontal cortex, whereas participants engaged in current or previous drug use showed relatively greater activation in the left orbitofrontal cortex.Conclusion:Our results indicate a disturbance in the mediation by the prefrontal cortex of a risky decision-making task associated with amphetamine and opiate abuse. Moreover, this disturbance was observed in a group of former drug users who had been abstinent for at least 1 year.