Brain activation during dual-task walking and executive function among older adults with mild cognitive impairment: a fNIRS study

Background and aims Dual-task walking (DTW) is thought to involve activation of the prefrontal cortex in healthy adults and to be affected by cognitive impairment. However, it is unclear whether prefrontal cortex activation is involved in DTW in older adults with mild cognitive impairment. This study examined brain activation during DTW among older adults with mild cognitive impairment using functional near-infrared spectroscopy. Methods Sixteen older adults (aged 75.4 +/- 7.2 years, women n = 6) performed gait experiments under normal walking and DTW conditions. We used a design with 60-s blocks consisting of a 10-s rest standing as pre-resting period, a 20-s walking task period, and a 30-s rest standing as post-resting period. Walking speed was measured during a 20-s walking task. Changes in oxy-hemoglobin were measured in the prefrontal area during gait experiments. Results Walking speed was slower during DTW compared with normal walking (p < 0.001). The oxy-hemoglobin level during DTW was higher than during normal walking (p < 0.001) and was correlated with executive function, as measured by Stroop interference (p < 0.05). Conclusion Our findings indicate that DTW is associated with prefrontal activation among older adults with mild cognitive impairment. The brain activation during DTW was correlated with executive function. Additional studies are necessary to elucidate the effects of cognitive impairment on the association between prefrontal activity and walking under various conditions.