Objective: To investigate the role of the frontal lobe during dual tasking and obstacle negotiation, in healthy older adults and patients with Parkinson’s disease (PD).

Background: Accumulating evidence suggests that gait is influenced by higher order cognitive and cortical control mechanisms, especially under challenging conditions. Functional near infrared spectroscopy (fNIRS) has been used to examine frontal lobe activity during walking in healthy older adults, reporting increased oxygenated hemoglobin (HbO2) levels during walking while dual tasking, compared to usual walking. Here, we aimed to investigate the role of the frontal lobe during two complex walking tasks; dual tasking and obstacle negotiation, in both healthy older adults and patients with Parkinson’s disease (PD).

Methods: We studied 38 healthy older adults (mean age 70.4±0.9 yrs; 20 men) and 68 patients with PD (mean age 71.6±0.9 yrs; 46 men). Frontal lobe activation was assessed using fNIRS. Assessments were performed under 3 walking conditions: 1) walking at a self-selected speed; 2) walking while dual tasking (DT); and 3) walking while stepping over obstacles. Linear mix models were used to detect changes between groups and within conditions.

Results: HbO2 levels were significantly different between walking conditions (p<0.001) but similar between groups. Patients with PD had higher activation during usual walking, compared to healthy older adults (p <0.030). During DT, Hb02 level increased in healthy older adults (p<0.001), as compared to usual walking, but not in patients with PD. In contrast, during obstacle negotiation, HbO2 level increased in patients with PD (p=0.001), but not in healthy older adults. Compared to the healthy older adults, dual task cost and obstacle cost in gait speed were higher (p<0.003) and performance on the cognitive dual task was worse (p=0.001) in patients with PD.

Conclusions: This study provides direct evidence to a different pattern of frontal activation during walking between patients with PD and healthy older adults. The increased HbO2 levels during usual walking in patients with PD indicate that the prefrontal cortex is utilized to compensate for striatal deficits. However, higher activation during obstacle negotiation and not during dual tasking demonstrates that the ability to additionally recruit prefrontal cortex depends on the nature of the task.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-role-of-the-frontal-lobe-in-complex-walking-among-healthy-older-adults-and-patients-with-parkinsons-disease-an-fnirs-study/