Dual-task cost (DTC) is the performance decline observed during simultaneous motor and cognitive tasks. It is associated with cognitive and physiological vulnerability. However, it remains unclear how specific frailty dimensions and cognitive domains contribute to DTC during arithmetic and verbal fluency tasks.

We aim to investigate the independent associations between physical, social and oral frailty dimensions versus cognition function with DTC in community-dwelling older adults.

We studied 281 participants from the GeriLABS-2 study. Physical frailty was assessed using Fried’s Frailty Phenotype, social frailty using the 8-item Social Frailty Scale (SF8) and oral frailty using the Oral Frailty Index-8 (OFI-8). Cognitive function was assessed with Chinese Mini Mental State Examination (CMMSE) and Chinese Frontal Assessment Battery (CFAB). DTC on gait was assessed with arithmetic (counting backwards from 100) and verbal fluency (animal naming) cognitive tasks. Association of DTC with frailty dimensions and cognition were evaluated via hierarchical linear regression, adjusted for demographics.

Higher CFAB score was significantly associated with lower DTC in both arithmetic (B=-2.067, p < 0.001) and verbal fluency (B=-1.489, p = 0.020) tasks, suggesting individuals with better executive function showed lower DTC. Social frailty (Factor 2 – social activity and financial resources) and oral frailty (Factor 3 – dietary and social habits) were significantly associated with DTC for arithmetic task (B = 2.664, p = 0.030; B = 3.718, p = 0.007). No significant association was observed for physical frailty. The final composite model showed that CFAB has a significant associated with DTC arithmetic (B=-2.012, p < 0.001) and DTC verbal fluency (B=-1.537, p = 0.016) tasks.

Cognitive frailty, particularly executive dysfunction, is a key factor contributing to difficulties with dual tasking. Social and oral frailty factors may influence DTC during arithmetic tasks, however their effects were attenuated after adjusting for cognition. Interventions addressing cognitive frailty may be a promising target for mitigating DTC in older adults.