Electrocortical Activity in Older Adults Is More Influenced by Cognitive Task Complexity Than Concurrent Walking

Abstract

Human cognitive-motor performance largely depends on how brain resources are allocated during simultaneous tasks. Nonetheless, little is known regarding the age-related changes in electrocortical activity when dual-task during walking presents higher complexity levels. Thus, the aim of this study was to investigate whether there are distinct changes in walking performance and electrocortical activation between young and older adults performing simple and complex upper limb response time tasks. Physically active young (23 ± 3 years, n = 21) and older adults (69 ± 5 years, n = 19) were asked to respond as fast as possible to a single stimuli or a double stimuli appearing on a touch screen during standing and walking. Response time, step frequency, step frequency variability and electroencephalographic (EEG) N200 and P300 amplitudes and latencies from frontal central and parietal brain regions were recorded. The results demonstrated that older adults were 23% slower to respond to double stimuli, whereas younger adults were only 12% slower (p < 0.01). The longer response time for older adults was accompanied by greater step frequency variability following double-stimuli presentations (p < 0.01). Older adults presented reduced N200 and P300 amplitudes compared to younger participants across all conditions (p < 0.001), with no effects of posture (standing vs walking) on both groups (p > 0.05). More importantly, the P300 amplitude was significantly reduced for older adults when responding to double stimuli regardless of standing or walking tasks (p < 0.05), with no changes in younger participants. Therefore, physically active older adults can attenuate potential walking deficits experienced during dual-task walking in simple cognitive tasks. However, cognitive tasks involving decision making influence electrocortical activation due to reduced cognitive resources to cope with the task demands.

Cognitive dual-task cost depends on the complexity of the cognitive task, but not on age and disease

“…Another factor involved in the interaction between gait and cognitive tasks is task complexity, but only a few studies have investigated its influence on cognitive DTC, with variable results. Some studies have reported higher cognitive DTC as cognitive task complexity increases (34)(35)(36). The effect seems to be influenced by age and cognitive domains involved (35-39).…”

“…Our results on SRT are in line with previous studies showing a deterioration in reaction time when performing another task simultaneously, such as contralateral movements (65), a secondary cognitive task (66), a postural task (67) or walking (68, 69). However, previous studies have reported that cognitive DTC is highly variable depending on several factors such as attention (70), age and gender (18,35,36,38,(71)(72)(73)(74), task type and difficulty (35,36,39,63,70,75), and these variables show a complex interaction. In addition, several studies have shown that cognitive performance in DT did not change compared to ST (17,[19][20][21] or even improved (17,18,20,29).…”

Allocation of cognitive resources in cognitive processing of rhythmic visual stimuli before gait-related motor initiation

“…The performance of human cognitive and motor functions largely depends on the allocation of brain resources in synchronous tasks (Vila-Cha et al, 2021). Under increasing task demands, maintaining adequate motor ability depends on the regulation and coordination of cognitive resources.…”

“…Additionally, the N1 component, which is closely related to the initial processing of a stimulus, can represent the demands of early perceptual processing (Hickey et al, 2020;Chen et al, 2022a,b). Finally, the P2 and P3 components of the ERP, representing the response to visual stimuli over the parietal region, are the most common indices for evaluation of cognitive resources (Yang et al, 2020;Reiser et al, 2021;Vila-Cha et al, 2021). The higher the amplitude of these components, the higher the consumption of cognitive resources is generally considered to be.…”