Changes in Oxyhemoglobin Concentration in the Prefrontal Cortex during Cognitive-Motor Dual Tasks in People with Chronic Obstructive Pulmonary Disease

Abstract

Cognitive and motor impairment are well documented in chronic obstructive pulmonary disease (COPD) patients, but their relationship has not been studied. This study evaluated and compared cognitive and motor performance during dual tasks and related dorsolateral prefrontal cortex (PFC) changes in oxygenated hemoglobin (ΔO₂Hb), a proxy measure of neural activity, in patients with COPD and age-matched healthy individuals. Participants performed three single tasks: (1) backwards spelling cognitive task; (2) 30 m preferred paced walk; (3) 30 m fast walk, and two dual tasks: (4) preferred paced walk + backwards spelling; (5) fast paced walk + backwards spelling. The ΔO₂Hb from left and right dorsolateral PFC were measured using functional near-infrared spectroscopy. Gait velocity was measured using a Zeno walkway. Compared to healthy adults (n = 20), patients with COPD (n = 15) had higher ΔO₂Hb during single preferred (-0.344 ± 0.185 vs. 0.325 ± 0.208 µM; p = 0.011) and fast paced walk (-0.249 ± 0.120 vs. 0.486 ± 0.182 µM; p = 0.001) in right PFC. Among healthy adults, ΔO₂Hb were higher bilaterally during preferred paced walking dual versus single task (right: 0.096 ± 0.159 vs. −0.344 ± 0.185 µM, p = 0.013; left: 0.114 ± 0.150 vs. −0.257 ± 0.175 µM, p = 0.049) and in right PFC during fast walking dual versus single task (0.102 ± 0.228 vs. −0.249 ± 0.120, p = 0.021). Patients with COPD did not increase O₂Hb during dual versus single tasks. Patients with COPD exhibited slower velocity than older adults during all walking tasks. The lack of further increase in O₂Hb from single to dual tasks in patients with COPD, may indicate reduced cognitive-motor capacity and contribute to poorer motor performance limiting safe ambulation. Dual tasking rehabilitation may improve neural efficiency to offset these risks.

Keywords:

• COPD
• prefrontal cortex
• near-infrared spectroscopy
• gait
• cognition

Acknowledgments

The study was approved by University of Toronto’s Research Ethics Board (protocol ID: 33466). The authors would like to acknowledge Dr. Hasan Ayaz for his technical support with fNIRS data, Meeran Manji, coordinator of the Pulmonary Rehabilitation Clinic at Toronto Western Hospital and a registered nurse, for her assistance with participant recruitment and Tyler Saumur for his assistance with the regression analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Research and Innovation Ontario [501683], Canada Foundation for Innovation [501682], Ontario Respiratory Care Society [503659], the Department of Physical Therapy [208294] and Rehabilitation Sciences Institute [100771] at the University of Toronto. The funding agencies had no involvement in the content of this manuscript.