Objective: This study investigated pre-frontal cortex (PFC) activation while walking in older adults and people with Parkinson’s disease (PD). We specifically examined 1) PFC activation in response to dual-task walking and 2) PFC activation over time.

Background: Gait deficits are common in PD, with links to reduced mobility and falls. Evidence demonstrates that gait is influenced by cognitive ability in PD and older adults, particularly executive-attention stemming from the PFC. PFC control may be required to compensate for sub-cortical deficits in automatic gait control in PD. However, this has yet to be established in PD (particularly when OFF their medication) and it is unclear how response varies over time for walking bouts of 2 minutes.

Methods: PFC activity was recorded in 10 healthy older adults (66.2±5.9 years) and 29 people with PD (67.6±5.5 years, MDS-UPDRS III 42.5±13.8) using functional near infra-red spectroscopy (fNIRS) while participants walked back and forth over 7m for 2-minutes under single and dual-task (AX-CPT). People with PD were tested OFF medication (at least 12hours washout). Linear mixed effects modelling (LMEM) in R Studio was used to assess the effect of task (single, dual), time (each 7m walk) and group (PD, control). The primary outcome was change in oxygenated hemoglobin (HbO2) from baseline standing, which is a proxy for cortical activity.

Results: Subjects with PD overall had significantly higher PFC activation (higher HbO2) than healthy elderly when walking (Group p=.003). Increased PFC HbO2 primarily occurred within the first and second 7m walk bout under both single and dual-task in PD, and under dual-task for healthy elderly. In contrast, under single-task conditions healthy elderly showed increased HbO2 only within the first walk bout (Task*Group p=.002). Dual-task increased PFC HbO2 for both groups (Task p=.018). Both groups also significantly reduced PFC activation over time (Time p=.003, Time*Group p=.655) across single and dual-task conditions (Task*Time p=.071).

Conclusions: People with PD showed greater PFC activation (higher HbO2) when walking compared to healthy elderly, but respond in a similar manner to attentional distraction when walking (dual-task). Over time, PFC activation while walking reduces in both PD and older adults, which may indicate a return to automatic movement control.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/return-to-automaticity-cortical-activity-during-gait-in-parkinsons-disease/