Association between insomnia and its symptoms and cognitive impairment in community-dwelling older adults in China: A multicenter study.

BackgroundLimited evidence exists on insomnia symptoms' association with mild cognitive impairment (MCI) and dementia in older Chinese adults across rural and urban areas.ObjectiveTo examine associations between insomnia symptoms, sleep duration, and cognitive impairment.MethodsThis cross-sectional study utilized data from China's Multicenter Dementia Survey (2019-2020), examining the association between insomnia symptoms, sleep duration, and cognitive impairment, using logistic and linear regression models. The cognitive score was obtained using the Mini-Mental State Examination (MMSE).ResultsWe included 10,725 participants (5964 females) aged between 65 and 100 years. Insomnia was significantly associated with an increased risk of MCI (odd ratio [OR], 1.16; 95% confidence interval [CI], 1.05 to 1.29) and lower MMSE scores (β, -0.13; 95% CI, -0.15 to -0.10). Difficulties initiating sleep (DIS; OR, 1.16; 95% CI, 1.03 to 1.31) and sleepiness during the day (SDD; OR, 1.32; 95% CI, 1.02 to 1.70) increased MCI risk, and the latter (OR, 1.79; 95% CI, 1.26 to 2.56) also increased risk of dementia. Insomnia's negative association with MMSE scores was stronger in rural (β, -0.17; 95% CI, -0.20 to -0.14) than urban residents (β, -0.05; 95% CI, -0.08 to -0.02). Sleep duration and MMSE scores showed an inverted U-shaped relationship (peak at 7-8 h/night).ConclusionsInsomnia symptoms, particularly DIS and SDD, are associated with higher MCI risk and poorer cognition in older adults, with amplified effects in rural China.