"Postural first" principle when balance is challenged in elderly people

Area of Science:

• Gerontology
• Biomechanics
• Cognitive Neuroscience

Background:

• Human cognitive processing has limitations, affecting simultaneous task performance.
• Cognitive load, the mental effort required to perform tasks, can influence motor control.
• Understanding how cognitive load affects balance in elderly individuals is crucial for fall prevention.

Purpose of the Study:

• To evaluate the effect of cognitive load on simple and complex postural tasks in noninstitutionalized elderly people.
• To investigate how cognitive load influences balance control under varying support conditions (firm vs. foam) and visual input (eyes open vs. eyes closed).

Main Methods:

• 128 noninstitutionalized elderly participants (mean age 73.6 ± 5.6 years) performed postural tasks.
• Tasks were conducted on firm and foam supports, with eyes open and closed.
• Cognitive load was manipulated using a control condition (CC) and a mental counting condition (MCC).
• Balance was assessed using sway path and center of foot pressure area on a force platform.

Main Results:

• On firm support, cognitive load (MCC) increased sway path compared to control (CC) in both eyes open and closed conditions (p < 0.001).
• On foam support, sway path was higher in CC than MCC with eyes closed (p < 0.001), and area was higher in CC than MCC in both eyes open (p < 0.05) and closed (p < 0.001) conditions.
• Cognitive load altered simple postural control, increasing energetic expenditure (sway path).

Conclusions:

• Cognitive load affects simple postural control, requiring increased effort, suggesting attentional resources are shared.
• Complex postural tasks are not perturbed by cognitive load, indicating postural control is prioritized under significant challenge (the "postural first" principle).
• Findings highlight the adaptive strategies in elderly balance control under dual-task conditions.