Objective: In this work we aimed to describe the brain oscillations associated with impaired novelty detection at early PD.

Background: Cognitive impairment, especially attentional and executive dysfunction, has been widely described in Parkinson’s disease (PD). Recently, we have shown that the P3a wave, an event-related potential associated with involuntary attention, is reduced from early stages of PD. Furthermore, the P3a might represent a biomarker of severity and disease duration for PD. Nevertheless, the brain oscillations underlying this reduction in the disease remain unclear.

Methods: Twenty one healthy participants similar in age, gender and education were included as control group. All participants performed an auditory involuntary attention task including frequent and deviant tones while a digital EEG was recorded. Time-frequency representations (3-40 Hz) of both total power and phase alignment (phase locking factor-PLF) were calculated for both types of tone. The P3a wave was obtained as well.

Results: We found diminished power and decreased PLF of delta-theta oscillations (3-7 Hz) in the P3a time-range (300-550 ms) after the onset of deviant stimuli in the PD group compared to controls (p<0.05) [figure 1 and 2]. This PLF was associated with P3a amplitude (p=0.001). Also, reduced total power in the alpha-beta range (8-25 Hz, 400-650 ms) was found in the PD group. Across participants, stronger alpha-beta power reduction for deviant vs. frequent tones was associated with improved attentional performance (digit span, p=0.006). Finally, we found diminished P3a amplitudes in the PD group (p=0.04) [figure 3] and years of evolution of PD were inversely associated with P3a amplitudes (p=0.02).

Conclusions: In conclusion, PD patients showed impaired oscillatory responses to novel stimuli both at slow and high frequencies. While phase alignment at delta-theta range accounted for the P3a, alpha-beta oscillations were associated with attentional capacity. Our results confirm that impaired novelty detection is a reliable cognitive feature of neurodegeneration from very early stages of PD.

References: Solís-Vivanco R, Rodríguez-Violante M, Rodríguez-Agudelo Y, Schilmann A, Rodríguez-Ortiz U, Ricardo-Garcell J. The P3a wave: A reliable neurophysiological measure of Parkinson’s disease duration and severity. Clin Neurophysiol 2015; 126:2142-2149.

Solís-Vivanco R, Ricardo-Garcell J, Rodríguez-Camacho M, Prado-Alcalá RA, Rodríguez U, Rodríguez-Violante M, Rodríguez-Agudelo Y. Involuntary attention impairment in early Parkinson’s disease: an event-related potential study. Neurosci Lett. 2011 May 16;495(2):144-149.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/oscillatory-dynamics-of-impaired-novelty-detection-at-early-parkinsons-disease/