Aging Diminishes The Direct Association Between Neurovascular Coupling And Postural Sway During N-back Task

Dual-tasking (i.e., performing two unrelated tasks at once), depends upon the timely activation of related brain regions. Neurovascular coupling (NVC) is the change in cerebral blood flow velocity (CBFv) in response to cognitive task performance. Prior research suggests that NVC declines with aging. Moreover, that reduced NVC of the middle cerebral artery (MCA) is associated with declines in executive function and slower walking speed in older individuals. However, the direct link between NVC and dual-task standing postural control remains unexplored in young and older adults. PURPOSE: To determine the association between NVC and postural sway during the performance of the n-back task of executive function METHODS: Twenty-six young adults (YA, aged = 26 ± 3 years) and 27 older adults (OA, aged = 76 ± 6 years) completed multiple trials of standing while completing the n-back. The n-back consisted of two experimental conditions (i.e., Identify X, [IdX] and 2-back) presented on a screen. CBFv of the MCA and postural sway were simultaneously recorded using transcranial Doppler and a lumbar motion sensor, respectively. NVC was quantified as the percent change in CBFv between the IdX and 2-back conditions. Postural sway measures were elliptical area (m2/s4), mean velocity(m/s), and range of acceleration (m/s2) averaged across trials. RESULTS: Within the YA group, NVC was negatively correlated with elliptical area (r = -0.54, p = 0.01) and mean velocity (r = -0.52, p = 0.02) during IdX; and elliptical area (r = -0.65, p < 0.001), mean velocity (r = -0.73, p < 0.001), and range of acceleration (r = -0.71, p = 0.001) during the 2-back condition. Within the OA group, however, NVC was only correlated with mean velocity during the IdX task (r = -0.60, p = 0.005). Models were independent of age, sex, and BMI. CONCLUSION: Lower NVC was directly linked to greater elliptical sway area, mean velocity, and acceleration range during the n-back, to a greater extent when performing the more demanding 2-back task and within the YA group. Understanding the functional neural activation of CBF could offer new insights into postural control. This knowledge might present a potential therapeutic target for individuals experiencing impaired postural control, particularly in dual-task scenarios. National Institute on Aging