Multimorbidity and Cognitive Function in Community‐Dwelling Older Adults in Shanghai: The Mediating Role of Sleep Quality

Multimorbidity and cognitive decline are highly prevalent among older adults. Although sleep disturbances are known to be associated with both conditions, the underlying mechanisms connecting multimorbidity to cognitive impairment remain poorly understood. To address this gap, a multi-center, population-based cross-sectional study was conducted to investigate the potential mediating role of sleep quality in the relationship between multimorbidity and cognitive decline. From June 2023 to March 2024, a total of 3574 community-dwelling adults aged 65 years or older were recruited from eight communities in Shanghai. After excluding participants with missing data (n = 672), the final analytical sample comprised 2902 individuals. Data were analysed using R Statistical Software. Among the 2902 participants (mean age 73.8 ± 7.9 years), fully adjusted models revealed two key findings: first, a significant association was observed between multimorbidity and cognitive decline (odds ratio = 1.152 per unit increase in the Chinese Multimorbidity Weighted Index); and second, sleep quality mediated 12.1% of this relationship (p = 0.004), a result that was confirmed through bootstrap validation for robustness. In conclusion, sleep quality partially mediates the positive association between multimorbidity burden and cognitive decline, accounting for approximately one-eighth of the total effect.