Central fatigue and attentional processing in Parkinson's disease: An event-related potentials study

Objective: To verify whether central fatigue in patients with Parkinson's disease (PD) is associated with the presence of a more severe selective cognitive impairment. Methods: Twenty-four PD patients without fatigue-PDnF, 11 with fatigue-PDF and 32 healthy volunteers underwent a P300 novelty task that elicits both the P3a and the P3b components. Results: P3b latency was significantly longer in both PDF and PDnF than in controls. P3b amplitudes were comparable between groups. P3a latency and P3a amplitude were respectively significantly longer and lower in PDF than in either PDnF or controls. Conclusion: The ability to discriminate the significant target stimulus, which requires the integrity of the dorsal attentional network and top-down control mechanisms, is compromised in parkinsonian patients irrespective of the presence of fatigue. PDF exhibited a difficulty in attentional orienting to salient novel stimuli, a bottom-up attentional control mechanism that is related to the functioning of the ventral attention network. Significance: Fatigue seems to be specifically related to an impairment in the processing of novel stimuli, which is an essential part of adaptive decision-making behavior.