Objective: This study aimed to explore dual-task (DT)-related cortical hemodynamic response (CHR) differences across healthy older adults (HOA), mild Parkinson’s disease (PD), and moderate PD in response to various cognitive-motor tasks.

Background: People with Parkinson’s disease (PwPD) have difficulty performing DTs, affecting overall function and quality of life. Prior research suggests that reductions in DT performance may serve as an early indicator of PD. Investigating CHR during DTs could improve understanding of the neural mechanisms underlying PD and potentially serve as an early indicator of pathology.

Method: Data from 35 PwPD and 11 HOAs were collected, including demographics (age, sex), PD severity (MDS-UPDRSIII), and CHR for oxygenated hemoglobin (HbO) using portable fNIRS during a dual-task (DT). The DT involved two gait tasks—straight-line walking (simple) and figure-8 walking with obstacle crossing (complex)—paired with one of two cognitive tasks: oral trail making test (OT) or spontaneous speech. fNIRS data were processed with MNE Python, incorporating short separation channels, and averaged into five regions of interest (ROIs): prefrontal cortex, premotor cortex (PMC), supplementary motor area (SMA), primary motor cortex, and superior parietal cortex. Participants were divided into HOA (n=11), mild PD (MDS-UPDRSII ≤ 32, n=24), and moderate PD (MDS-UPDRSIII > 32, n=11). Kruskal-Wallis tests compared hemodynamic responses between groups, with significant results further analyzed using Mann-Whitney U tests.

Results: Simple gait with spontaneous speech elicited differences in regional HbO levels between the HOA and mild PD groups, specifically in the PMC and SMA (ps<0.011). Post hoc tests showed differences between HOA and mild PD (ps<0.009) and mild and moderate PD (ps=0.023), but not between HOA and moderate PD. No differences were found between HOAs and mild PD across DTs.

Conclusion: These results highlight early neural changes in PD, particularly during lower complexity DT walking. Differences were observed between HOA and mild PD, but not between mild and moderate PD, in both the PMC and SMA during a low complexity DT. This suggests reduced recruitment of these regions during DTs, potentially indicating attenuated and uncompensated neural processing in SMA and PMC in early PD, which can be elicited by low complexity DTs.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/dual-task-elicited-premotor-and-supplementary-motor-activity-as-sensitive-markers-of-mild-parkinsons-disease-an-fnirs-analysis/