Reduced belief updating impairs adaptive step initiation in older adults

Abstract

Ageing is associated with declines in mobility and balance that threaten independence and increase the risk of falls. Although these changes are often attributed to deterioration of muscular and sensory systems, growing evidence suggests that age-related alterations in cognitive control also contribute to postural instability and gait impairments. Here, we examined whether shifts in cognitive control strategy underlie impaired gait initiation in older adults by modelling how individuals update beliefs about upcoming actions. Older and younger adults performed a choice-stepping go/no-go task in which the likelihood of initiating a step was manipulated across trials. We measured anticipatory postural adjustments (APAs), the preparatory shifts in body weight that precede stepping, and modelled age-related differences in APA onset using a hierarchical Bayesian framework. Older adults initiated APAs more slowly than younger adults, particularly following repeated go trials. Computational modelling revealed reduced learning rates and heightened sensitivity to uncertainty in older adults. These findings identify altered belief updating as a cognitive mechanism shaping age-related changes in adaptive stepping behaviour.