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.