Recent evidence of obesity-related changes in the prefrontal cortex (PFC) during cognitive and seated motor activities have surfaced; however, the impact of obesity on PFC regulation during ambulation remains unclear. The purpose of this study was to determine obesity-specific differences in prefrontal cortex activation using functional near infrared spectroscopy (fNIRS) during single- and dual-task walking situations in older adults. Ten non-obese and ten obese individuals, 65 years and older, performed single (walking) tasks and dual (walking with: verbal, motor, precision gait, and decision-making) tasks. Maximum oxygenated hemoglobin (HbO2) was measured bilaterally using a portable fNIRS system. Gait speed and performance on the dual tasks were also obtained.
Dual-task conditions, namely precision gait and decision-making tasks, were associated with greater PFC activity compared to the single-task condition (both P < 0.0001) despite the precision gait task being associated with slower gait speeds (P = 0.0001). Obesity was marginally associated with greater activation in the PFC during the single- and dual-task conditions (P = 0.057) despite both obesity groups having comparable gait speeds (P = 0.229) and performances in the secondary tasks (all P > 0.232). The study is one of the first to examine the dependence of gait on PFC function in non-obese and obese older adults during walking and dual-tasks using fNIRS. These preliminary findings have strong public health implications in identifying individuals who are at greater risks of falls, particularly when performing complex mobility tasks.
- Mehta, Ranjana Associate Professor