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DRUG ABUSE, HIV, AND THE BRAIN
Neuroeconomics: New Approaches to Risky Decisionmaking
Gregory S. Berns, M.D., Ph.D.
Within the past 5 years, neuroeconomics has matured as a new approach of using brain imaging to both test and expand economically-based theories of decisionmaking. In this presentation, the basic principles of expected utility and prospect theory are described. Recent brain imaging experiments based on these theories suggest common neural substrates in the brain that weigh the costs and benefits of potential decisions as well as the risk that an individual places on them. These experiments suggest promising approaches to using brain imaging to predict future decisions.
Neuroimaging To Predict High-Risk Behaviors in Methamphetamine Users
Martin P. Paulus, M.D.
Relapse is an important clinical aspect of substance dependence. Many factors contribute to relapse, but its neurobiological basis is poorly understood. We have used a simple decisionmaking task in the context of functional magnetic resonance imaging in 40 methamphetamine-dependent individuals who completed a 28-day inpatient program to predict whether the patterns of brain activity predict relapse. Brain activation levels in the right insula, right posterior cingulate, and right middle temporal gyrus correctly predicted the outcome in 19 of 22 individuals who did not relapse and in 17 of 18 who returned to methamphetamine use. This result demonstrates that functional neuroimaging may be useful for long-term clinical predictions in substance dependence.
NeuroAIDS in Drug Users
Justin McArthur, M.D.
[Abstract Not Available]
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Methamphetamine and HIV: CNS Effects
Igor Grant, M.D.
Methamphetamine and HIV infection each can produce brain disease, and there is evidence that their co-occurrence may produce additive effects on neural injury. Approximately 40 percent of methamphetamine (METH+) abusers who are HIV-uninfected have some neurocognitive impairment, and a similar proportion of HIV-infected individuals (HIV+) who are not methamphetamine abusers are also impaired. More than 60 percent of persons who are HIV+ METH+ have cognitive disturbance, suggesting an additive effect. Although there may be some common pathways (e.g., the induction of neuroinflammatory cascades) that underlie this apparent synergy, there are also differences in the neuropathogenic mechanisms. For example, although atrophy of selected brain regions is a common correlate of HIV disease of the brain, one sees increases in the volumes of certain brain structures with methamphetamine. Furthermore, neuropathologic studies indicate that in addition to the generally accepted effect of methamphetamine on dopaminergic circuitries, there may be a selective loss of calbindin immunoreactive interneurons in the brains of those affected by both HIV and METH. Disturbances in neurocognitive functioning associated with methamphetamine may also be associated with declines in everyday functioning, and deficits in decisional abilities could influence the likelihood of engaging in risk behaviors or not adhering to treatment that could affect HIV disease progression and transmission.
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