Gambling behavior in Parkinson's Disease: an EEG study using Iowa Gambling Task

Characteristics related to the development of Pathological Gambling (PG) in Parkinson’s Disease (PD) include personality traits, such as impulsivity, cognitive deficits and the dopaminergic treatment. In the last ten years there was a growing interest towards the study of PD’s subgroups of patients with PG, because of the serious personal, social and economic consequences that this disease causes for the patient and his family. Indeed, PG could be defined as a dysfunctional compulsive behavior related to decision making in high risk decisions. A well-validated task used to test the ability to distinguish between high and low risk decisions and to evaluate the situational learning effect is the IOWA Gambling Task (IGT). This study investigates the differences in the decision processes in PD patients with and without PG considering both neurophysiological and behavioral aspects. The sample included fifty-two PD patients (43 males e 9 females, mean age 63,06 years old), in a stable dopaminergic treatment and without dementia. According to their gambling status, participants were divided into three groups: 17 PD patients with active gambling behavior (PDG), 15 PD patients who remitted from PG (PDNG), and a control group (CG) composed of 20 patients with PD only. An EEG registration was carried out during the IGT performance and was analyzed observing the cortical oscillations (time-frequency analysis). EEG results showed an increase of the low frequency bands (Delta and Theta) in the frontal area for the PDG group compared to the other two groups, mainly during disadvantageous and risky options. Instead, the PDNG group revealed a power distribution similar to the CG. At the behavioral level, an impairment in the ability to opt for most advantageous options was observed, with a decreasing gradient from PDG to PDNG to CG. Moreover, this tendency was highly related to impulsivity traits (measured by the Barratt Impulsivity Scale, BIS-11) and reward dependence (BIS/BAS questionnaire subscales score). Overall, the dysfunctional cognitive performance and a low frequency bands response could underline an anomalous cortical answer of PDG patients related to their ability to monitoring and controlling the emotional behavior during a decision-making task where impulsivity and reward mechanisms correlated to risky dynamics are relevant