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Dr. Okun

Post of the Week: How Scientists Determine Reward Behavior and Impulsivity in Parkinson's Disease

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Dear Forum members.


People often ask, "how do you know PD patients have abnormalities in impulsivity, risk taking, and in what is referred to as reward behavior. This recent study examines a task called the Iowa Gambling Task that is designed to tease out these issues. It turns out that not only are PD patients at risk but dopamine drugs like agonists may push them into impulsive behaviors (impulse control disorders- gambling, shopping, infidelity, etc.).


Here is the abstract from pubmed:


J Clin Exp Neuropsychol. 2010 Dec 6:1-15. [Epub ahead of print]

Iowa Gambling Task in Parkinson's Disease.

Poletti M, Cavedini P, Bonuccelli U.


Neurology Unit, Unita Sanitaria Locale of Viareggio, Viareggio, Italy.


Cognitive impairments are common in patients with Parkinson's disease (PD) from the early stages. Recent studies reported that medicated PD patients have poor performances, with respect to age-matched healthy controls, in a decision-making task like the Iowa Gambling Task (IGT), which detects the ability to alter choice behavior in response to fluctuations in reward contingencies. The IGT principally activates functions related to the orbitofrontal cortex, which plays a crucial role in the generation of outcome expectancies and processing of rewards. The analysis of IGT performances of PD patients is of particular interest because PD represents a good clinical model to study reward processing when its neural bases are affected by a neuropathology or are overdosed by dopaminergic therapies. As a matter of fact, either PD-related neuropathology in advanced stages of the disease or the dopamine replacement therapy from earlier stages of PD may affect the functioning of the orbitofrontal cortex. Three causal hypotheses on a dysfunctional decision making in PD patients, as assessed by IGT, are discussed. Finally, the possible relation between the phenomenon of decision-making impairment and impulse control disorders, a psychiatric complication observed with increasing frequency in PD patients, is discussed.


PMID: 21140314 [PubMed - as supplied by publisher]


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