Perceived workload vs. objective performance during dual-tasking in adults with mild cognitive impairment

Abstract Older adults with mild cognitive impairment (OAwMCI) demonstrate reactive balance deficits (impaired responses to external perturbations) compared to cognitively intact older adults (CIOA), which are exacerbated while performing a cognitive task (i.e., dual-tasking). However, it is unknown if these cognitive-motor deficits (which could significantly increase fall risk) can even be perceived by OAwMCI. Thus, this study examined if objective performance during dual-task reactive balance control (cognitive errors, reactive center of mass (COM) stability) was associated with subjective workload in OAwMCI and CIOA. 34 OAwMCI (Montreal Cognitive Assessment (MoCA): 18-25) and 35 CIOA (MoCA ≥26) were exposed to a support surface perturbation while performing a visuomotor “Target” task, which involved rotating their head to catch virtual objects. This task was also completed while seated (single-task). Participants rated their perceived workload (0-100) on the NASA-Task Load Index (NASA-TLX) in six domains (mental, physical, temporal, performance, effort, frustration). OAwMCI reported lower mental demand, effort, and frustration than CIOA in single and dual-task (p < 0.05), although had higher cognitive errors and lower reactive COM stability (p < 0.05). Both groups reported higher workload in dual vs. single-task (p < 0.05). NASA-TLX scores were not correlated with objective performance in OAwMCI (p > 0.05), although were significantly correlated with cognitive errors and reactive COM stability in CIOA (Pearson’s r: 0.3-0.5). These results suggest that OAwMCI may not be able to accurately perceive the cognitive-motor demands of challenging conditions. This impaired perception could affect the execution or scaling of reactive balance responses and contribute to increased fall risk, especially in dual task conditions.