Aging and dual-task walking: evidence of reduced motor automaticity independent of cognitive cost

Abstract

Background: Aging involves structural and functional changes in the central nervous system, affecting frontoparietal networks and cortico-subcortical circuits related to executive control and motor planning. Although gait is often considered predominantly motor, it relies on the integration of motor and cognitive systems. In young adults, gait occurs with high automaticity and low attentional demand; however, with advancing age, greater cortical recruitment is required to maintain performance, particularly under dual-task (DT) conditions, when attentional resources must be shared. Socioeconomic factors also influence cognitive and motor performance throughout life through cognitive reserve associated with education and environmental stimulation. This study was approved by the Ethics Committee of HCFMUSP (67388816.2.0000.0065). Objective: To compare motor and cognitive performance during dual-task walking between healthy young adults and older adults matched for sex, education, and socioeconomic status, and to analyse the effects of the cognitive task on spatiotemporal gait parameters. Methods: A cross-sectional observational study (STROBE) included 94 participants: 46 young adults and 48 older adults, with no neurological diagnosis and independent ambulation. The Brazilian Economic Classification Criterion, MoCA, BDI, or GDS were administered. Gait was assessed using the GAITRite® system under three randomised conditions: single motor task, single cognitive task, and DT. The DT consisted of walking while generating words beginning with a predetermined letter, with no prioritisation instructions. Cognitive performance was measured by the number of correct words, and cognitive cost was calculated as (DT − ST)/ST. Mixed 2×2 ANOVA and ANCOVA were performed (p≤0.05). Results: Groups were comparable in sex, education, and socioeconomic status. Significant group-by-condition interactions were observed for step length, stride length, single and double support times, total support time, and gait cycle time (p<0.05). Post hoc analyses showed that only older adults exhibited significant reductions in step length, stride length (p<0.001), and single support time (p<0.001), along with increases in double support time (p<0.001), stance (p<0.001), and gait cycle time (p=0.003) under DT conditions. Young adults showed only a reduction in foot progression angle (p=0.0003). Cognitive cost did not differ significantly between groups (p=0.098). Conclusion: Aging is associated with progressive alterations in spatiotemporal gait dynamics under dual-task conditions, characterised by a more cautious gait pattern and reduced motor automaticity, independent of cognitive cost. These findings highlight the importance of motor training interventions aimed at preserving locomotor efficiency.