Cognitive Impairment Alters Cortical Adaptation and Gait Regulation During Obstacle Walking in Patients With Parkinson’s Disease: Evidence From Temporal fNIRS and Gait Dynamics

OBJECTIVE: Obstacle crossing during walking poses a major risk of falling among individuals with Parkinson's disease (PD), particularly those with cognitive impairment. Although cognitive decline worsens gait, its specific effects on gait performance and cortical activation during obstacle walking remain unclear. The dynamic interaction between brain activity and gait across different walking phases is especially understudied in PD patients with mild cognitive impairment (PD-MCI) compared with those without cognitive impairment (PD-non-MCI). METHODS: Nineteen PD-non-MCI and fifteen PD-MCI participants performed obstacle walking, and functional near-infrared spectroscopy was used to measure activation in the prefrontal cortex (PFC), supplementary motor area (SMA), and premotor cortex (PMC). Gait parameters (speed, cadence, stride length, and stride time) and obstacle crossing metrics (crossing speed, stride length, stride time, and step width) were analyzed across early (5-20 s) and late (20-40 s) phases. Generalized estimating equations were used to examine group, phase, and interaction effects. Brain-gait associations were assessed using Spearman's correlations. RESULTS: PD-MCI participants exhibited poorer obstacle walking performance than PD-non-MCI participants, but no significant phase-related behavioral change was observed. Both groups showed higher PFC, SMA, and PMC activation during the early phase, reflecting greater neural engagement at task onset. However, SMA and PMC activation decreased more steeply across phases in the PD-MCI group. In PD-MCI patients, obstacle walking performance correlated negatively with early-phase PMC and late-phase PFC activation. CONCLUSION: PD-MCI participants had poorer gait and greater cortical activation, indicating increased neural effort and reduced efficiency. These. RESULTS: highlight altered brain-gait coupling in PD-MCI patients and emphasize the need for interventions that increase neural efficiency during complex walking.