Physical and cognitive function to explain the quality of life among older adults with cognitive impairment: exploring cognitive function as a mediator

BACKGROUND: Physical and cognitive function are both indicators of aging, characterized by a loss of adaptive response to life challenges and functional limitations, subsequently affecting their quality of life. This study aimed to identify the direct effect of physical function and the indirect effect of cognitive function on the quality of life in older adults with mild cognitive impairment. METHODS: The study participants were 79 older adults recruited from community centers in four urban districts of Korea. All participants completed a self-reported questionnaire for demographic characteristics and outcome variables. Outcome measures included physical function (grip strength, balance, and mobility), cognitive function, and mental and physical components of quality of life (QOL). Statistical analyses were conducted using hierarchical multiple linear regression and the PROCESS macro for mediation analysis. RESULTS: The mean age of participants was 77.46 years old with an elementary or lower education level (53.2%). The mean score of cognitive function was 16.39 (SD = 6.5). Physical function (grip strength, balance, mobility) and cognitive function explained 25% of the variance in physical (p = 0.004) and 29% in mental (p < 0.001) components of QOL after controlling for age, sex, and education level. Mobility was associated with both physical (β=-0.27, p = 0.024) and mental (β=-0.36, p = 0.002) components of QOL. The cognitive function partially mediated the relationship between balance and the physical component of QOL; the proportion of mediation was 55%. CONCLUSION: In conclusion, physical and cognitive function were significant predictors of QOL in older adults with cognitive impairment. Specifically, balance has significant indirect effects on the physical component of QOL through cognitive function as a mediator. Health-promoting strategies could be more effective when focusing on the direct effect of physical function as well as the mediating effect of cognitive function to promote the quality of life in this population.