Dual task reactive balance control in older adults with mild cognitive impairment: does the cognitive task domain make a difference?

Older adults with mild cognitive impairment (OAwMCI) demonstrate higher cognitive-motor interference (CMI) than cognitively intact older adults (CIOA) during dual tasking. However, studies have rarely examined how dual tasking affects reactive balance control in OAwMCI, or the effect of different cognitive task domains. This study compared how four cognitive tasks affected CMI during reactive balance control in OAwMCI vs. CIOA. In this study, 38 OAwMCI [Montreal Cognitive Assessment (MoCA): 18-25] and 38 CIOA (MoCA ≥ 26) were included and exposed to anterior support surface perturbations in single task and while performing four cognitive tasks: two visuomotor tasks (Target, Track), auditory clock test (ACT), and letter number sequencing (LNS). Cognitive tasks were also completed during unperturbed standing. In both single and dual task conditions, OAwMCI had a higher fall rate and lower reactive center of mass (COM) stability than CIOA. Reactive balance performance deteriorated in both groups while performing Target and Track, although was not affected by ACT or LNS. Cognitive performance was lower in dual vs. single task on the Target, Track, and LNS for both groups, although OAwMCI had higher cognitive costs than CIOA. These findings suggest that dual tasking could increase fall risk in both OAwMCI and CIOA, although visuomotor tasks induced greater CMI than executive function/working memory tasks, suggesting greater sharing of resources with reactive balance control. Furthermore, OAwMCI could experience higher CMI due to damage in sensorimotor areas involved in triggering/executing reactive balance responses, along with multidomain cognitive decline. Comprehensive dual task assessments could identify domain-specific cognitive decline in OAwMCI.