Methamphetamine Users: Do Brain Function Differences Predispose to Risky Behavior?

MedicalResearch.com Interview with
Dr. Edythe  D.London PhD Professor, Departments of Psychiatry and Biobehavioral Sciences, and Molecular and Medical Pharmacology David Geffen School of Medicine, UCLA Dr. Edythe  D.London PhD
Professor, Departments of Psychiatry and Biobehavioral Sciences, and Molecular and Medical Pharmacology
David Geffen School of Medicine, UCLA

MedicalResearch: What are the main findings of the study?

Dr. London: Brain function related to risky decision-making was different in stimulant users  (methamphetamine users) than in healthy control subjects. In healthy controls, activation in the prefrontal cortex (right dorsolateral prefrontal cortex) during risk-taking in the laboratory was sensitive to the level of risk. This sensitivity of cortical activation was weaker in stimulant users, who instead had a stronger sensitivity of striatum activation. The groups also differed in circuit-level activity (network activity) when they were not performing a task but were “at rest.”  Stimulant users showed greater connectivity within the mesocorticolimbic system, a target of abused drugs. This connectivity was negatively related to sensitivity in the prefrontal cortex to risk during risky decision-making. In healthy control subjects, connectivity between the right dorsolateral prefrontal cortex and striatum was positively related to sensitivity of prefrontal cortical activation to risk during risky decision-making.

MedicalResearch: Were any of the findings unexpected?

Dr. London: It was not unexpected that the mesocorticolimbic system differed in stimulant users than in healthy controls or that a functional link in the intrinsic connectivity between the prefrontal cortex and striatum is related to brain function during risk-taking. Still this type of research is very new – and it demonstrates that heightened intrinsic activity in the mesocorticolimbic system, coupled with reduced connectivity of the prefrontal cortex, may create a bias toward reward-driven behavior over self-control in stimulant users.

MedicalResearch: What should clinicians and patients take away from your report?

Dr. London: Interventions to improve this balance may enhance treatment for stimulant dependence and other disorders that involve maladaptive decision-making.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. London: Future research might focus on behavioral and pharmacological interventions to restore the balance by down regulating the mesocorticolimbic system.

Citation:

Risky Decision Making, Prefrontal Cortex, and Mesocorticolimbic Functional Connectivity in Methamphetamine Dependence