Sleep problems and mild cognitive impairment among adults aged ≥50 years from low- and middle-income countries

Background: The limited available literature suggests that sleep problems are linked to an increased risk of mild cognitive impairment (MCI). However, this association has been little studied to date in low-income settings. Objective: To investigate the association between sleep problems and MCI in a large sample of adults from six low-and middle-income countries (LMICs). Design: Cross-sectional. Setting: Study on Global Ageing and Adult Health (SAGE). Subjects: 32,715 individuals aged >= 50 years with preservation in functional abilities [age range 50-114 years; 51.7% females]. Methods: MCI was defined using the National Institute on Aging-Alzheimer's Association criteria. Sleep problems were assessed by the question "Overall in the last 30 days, how much of a problem did you have with sleeping, such as falling asleep, waking up frequently during the night or waking up too early in the morning?" and categorized as "None", "Mild", "Moderate", "Severe/Extreme". Multivariable logistic regression analysis and meta-analysis were conducted. Results: Compared to no sleep problems, mild, moderate, and severe/extreme sleep problems were associated with significant 1.40, 1.83, and 2.69 times higher odds for MCI with similar associations being observed between age groups and sex. Severe/extreme sleep problems were positively associated with MCI (i.e., OR > 1) in the six countries studied with the overall estimate being OR = 1.80 (95% CI = 1.50-2.16), and a low level of betweencountry heterogeneity was observed (I-2 = 28.2%). Conclusions: Sleep problems were associated with higher odds for MCI. Interventions to improve sleep quality among middle-aged and older adults in LMICs may be an effective strategy in reducing risk of MCI and dementia.