The Role of the Frontal Lobe in Complex Walking among Patients with Parkinson's Disease and Healthy Older Adults: An fNIRS Study

Background. Gait is influenced by higher order cognitive and cortical control mechanisms. Functional near infrared spectroscopy (fNIRS) has been used to examine frontal activation during walking in healthy older adults, reporting increased oxygenated hemoglobin (HbO2) levels during dual task walking (DT), compared with usual walking. Objective. To investigate the role of the frontal lobe during DT and obstacle negotiation, in healthy older adults and patients with Parkinson's disease (PD). Methods. Thirty-eight healthy older adults (mean age 70.4 ± 0.9 years) and 68 patients with PD (mean age 71.7 ± 1.1 years,) performed 3 walking tasks: (a) usual walking, (b) DT walking, and (c) obstacles negotiation, with fNIRS and accelerometers. Linear-mix models were used to detect changes between groups and within tasks. Results. Patients with PD had higher activation during usual walking (P <.030). During DT, HbO2 increased only in healthy older adults (P <.001). During obstacle negotiation, HbO2 increased in patients with PD (P =.001) and tended to increase in healthy older adults (P =.053). Higher DT and obstacle cost (P <.003) and worse cognitive performance were observed in patients with PD (P =.001). Conclusions. A different pattern of frontal activation during walking was observed between groups. The higher activation during usual walking in patients with PD suggests that the prefrontal cortex plays an important role already during simple walking. However, higher activation relative to baseline during obstacle negotiation and not during DT in the patients with PD demonstrates that prefrontal activation depends on the nature of the task. These findings may have important implications for rehabilitation of gait in patients with PD.