(WITHDRAWN) The Effects of Multiple Chronic Conditions on Cognitive Decline Among Older Koreans: Findings from the Korean Longitudinal Study of Ageing 2006-2016

Background: More than half of Korean older adults have two or more chronic conditions, often known as multiple chronic conditions (MCC). MCC is reported to be associated with increased risk of mortality, functional limitation and hospitalization. Also, individuals with MCC face greater challenges such as higher healthcare cost and contraindicated care compared to those with no or single chronic condition. Because MCC requires effective self-management (e.g., medication adherence, self-monitoring, diet control, physical activity) to prevent co-occurrence of new condition, maintaining healthy cognition becomes a crucial factor for this population. Nevertheless, little is known about the longitudinal relationship between MCC and cognitive function among Korean older adults. Thus, our study aims to investigate the effects of MCC on cognitive decline and further explore the factors associated with greater rate of decline within each three MCC group (i.e., 0, 1, and 2+) over a 10-year period.

Methods: The six waves (2006-2016) of Korean Longitudinal Study of Ageing (KLoSA) were used in this study. Our sample included N=2,198 individuals aged 65 and older, who were cognitively healthy (Korean Mini-Mental State Examination (K-MMSE) ≥ 24) at baseline (2006). The number of chronic conditions was counted out of 9 conditions including high blood pressure, diabetes, cancer, lung disease, heart problem, stroke, psychiatric problem, arthritis, and liver disease. Individuals were categorized into three groups: 1) no chronic condition (n=831), 2) one chronic condition (n=813), and 3) two or more chronic conditions (n=554). The K-MMSE was used to measure changes in cognitive function (i.e., memory, processing speed, orientation, language) over a 10-year period (range: 0-30). Baseline sociodemographic and health-related factors were included as covariates. Mixed effects model analyses were conducted using the SAS 9.4.

Results: Although on average, subjects experienced cognitive decline over a 10-year period, the rate of decline was significantly different across the three MCC groups (p <.001). Specifically, individuals with two or more chronic conditions showed greater cognitive decline compared to those with no or one chronic condition. Further, the results of the stratified analysis showed that different factors are associated with greater rates of cognitive decline within each MCC group. Among those with no chronic condition, being older, having lower income, lower education, and no functional limitation were associated with greater rate of cognitive decline. Among those with one chronic condition, being older, unmarried, not working, reporting poorer self-rated health, and having arthritis were associated with greater rate of cognitive decline. Among those with two chronic conditions, being older, having lower income, unmarried, and living alone were associated with greater rate of cognitive decline over a 10-year period.

Conclusions: Our findings indicate that individuals with MCC may experience greater rate of cognitive decline than those with no or one chronic condition among Korean older adults. Furthermore, the results indicate that risk factors that contribute to cognitive decline may differ across the three MCC groups. Thus, patient-centered self-management programs that specifically target those with and without MCC may be needed to mitigate cognitive decline among Korean older adults.