Multimorbidity and cognitive decline related functional limitations in middle-aged and older Chinese

Background: Our study aimed to investigate the association between multimorbidity and the cognitive decline related functional limitations. Methods: Data were obtained from the 2011–2018 China Health and Retirement Longitudinal Study, and generalized estimating equation models were used for estimation. A Chinese multimorbidity-weighted index (CMWI) was used to quantify the cumulative disease burden of multimorbidity. A margin plot was used to show the probability of functional limitations by global cognitive function and CMWI. Then, subgroup analysis was performed by demographic factors, the severity of functionally impaired ADL/IADL, and the trajectories of cognitive function. Results: Multimorbidity was demonstrated to be associated cognitive decline related functional limitations over 8 years, with the coefficient of the interaction of cognitive function −0.001 (−0.001, −0.001). This moderating effect was only significant in the relationship between cognitive function and ≥2-item impaired ADL/IADL (coefficient = −0.008, 95% CI: 0.009, −0.007) but was not significant in the relationship between cognitive function and 1-item impaired ADL/IADL. The accelerated role of multimorbidity associated with more severe function limitations than the relatively mild limitations attributed to cognitive decline, and the role of multimorbidity was stronger in individuals with continuously high function of cognitive trajectories and gradually declining cognitive function than in those with low level of cognitive trajectories. Conclusions: Effectively managing multimorbidity is important for preventing cognitive decline. Preventing the onset and progression of multimorbidity may be one potential strategy for early prevention and intervention to reverse or postpone cognitive decline and its further dementia risk.