The association between sleep quality and cognitive impairment among a multi-ethnic population of middle-aged and older adults in Western China: a multi-center cross-sectional study

Objective: This study aims to investigate the relationship between sleep quality and cognitive impairment in middle-aged and older adults living in Western China. Methods: Baseline data from the West China Health and Aging Trend (WCHAT) study were utilized, with enrollment of participants aged 50 years or older. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), where a PSQI score > 5 indicated poor sleep quality. The cognitive status was evaluated using the 10-item Short Portable Mental Status Questionnaire (SPMSQ). Multinomial logistic regression was applied to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Results: A total of 6,728 middle-aged and older adults dwelling in western China (age = 62.39 +/- 8.925 years, 2,520 males and 4,208 females) were included in the analysis. The prevalence of mild cognitive impairment was 11.0%, with 4.3% having moderate to severe cognitive impairment. Poor sleep quality was found in 47.7% of participants. After adjusting for age, gender, education, marital status, and chronic disease, poor sleep quality (OR = 1.29, 95% CI: 1.1-1.52, p = 0.002) was associated with a higher risk of mild cognitive impairment. Among specific sleep dimensions, there is a significant association between high daytime dysfunction and mild cognitive impairment (adjusted OR = 1.96, 95% CI: 1.45-2.62) as well as moderate to severe cognitive impairment (adjusted OR = 3.15, 95% CI: 2.09-4.73) in the middle-aged and older adults residing in multi-ethnic areas of western China. Besides, a sleep duration of 6-7 h was associated with a reduced risk of mild cognitive impairment (OR = 0.80, 95% CI: 0.65-0.98) and moderate to severe cognitive impairment (OR = 0.71, 95% CI: 0.51-0.99). Stratified analysis showed that poor sleep quality-particularly daytime dysfunction-was significantly associated with moderate to severe cognitive impairment in Han (OR = 4.14, 95%CI: 1.65-10.23), Tibetan (OR = 3.45, 95% CI: 1.42-8.1), and Yi (OR = 4.04, 95%CI: 1.46-10.97) participants, but not in Uyghur and Qiang groups. Conclusion: Sleep quality is significantly associated with cognitive impairment among middle-aged and older adults in Western China, particularly concerning the components of daytime dysfunction.