Objective: To assess response inhibition and strategic decision-making abilities associated with fatigue in Parkinson’s disease (PD).

Background: PD-related fatigue is defined as a feeling of exhaustion, a complete depletion of energy, or an increased effort disproportionate to attempted activities [1]. It has been hypothesized to result from the alteration of a complex cognitive elaboration involving costs/benefits analysis and decision making, which critically relies on the striato-thalamo-prefrontal circuit [2].

Method: The Iowa gambling task (IGT), a standardized task designed to measure the reward-based decision-making process [3], was administered to 38 PD patients, divided in two groups according to the presence of fatigue and to 15 healthy controls. IGT outcomes were: the total IGT index, calculated by subtracting the number of selected disadvantageous cards from the number of advantageous cards throughout 100 trials, and two additional indexes according to the first 40 trials (learning block) and the second 60 trials (performance block).

Results: Total IGT index did not differ between groups (p= 0.09), neither did the “learning” index: (p=0.19). A significant difference emerged in the “performance” index (p=0.045) with PD patients with fatigue presenting more disadvantageous choices than PD patients without fatigue (p =0.036). No difference emerged between groups in clinical characteristics (age at onset, disease duration and severity, levodopa equivalent dose) or associated symptoms (anxiety, depression, apathy, sleep).

Conclusion: PD patients with fatigue tended to make decisions in which short-term rewards are chosen without considering long-term negative outcomes, indicating that PD-related fatigue is associated with an impairment in strategic decision-making process. The integrity of the orbito-medial prefrontal cortex (OMPFC) network is necessary to control affective and motivational processes related to decision-making behavior. In physiological conditions, value-based decision-making involves trading off the cost associated with an action against its expected reward; it is possible that pathological fatigue emerged due to a failure in the interpretation of the relevance of stimuli (representation of reward value as well as perceived effort) as a consequence of OMPFC network dysfunction.

References: 1. Kluger BM, Krupp LB, Enoka RM. Fatigue and fatigability in neurologic illnesses: Proposal for a unified taxonomy. Neurology. 2013;80(4):409-416. doi:10.1212/WNL.0b013e31827f07be
2. Chaudhuri A, Behan PO. Fatigue and basal ganglia. J Neurol Sci. 2000;179(1-2):34-42. doi:10.1016/S0022-510X(00)00411-1
3. Brevers D, Bechara A, Cleeremans A, Noël X. Iowa Gambling Task (IGT): Twenty years after – gambling disorder and IGT. Front Psychol. 2013;4(SEP). doi:10.3389/fpsyg.2013.00665

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MDS Abstracts - https://www.mdsabstracts.org/abstract/strategic-decision-making-in-parkinsons-disease-with-fatigue/