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Aim: The association between visual impairment and mild cognitive impairment (MCI) has not been investigated to date. Thus, we assessed this association among older adults from six low- and middle-income countries (LMICs) (China, India, Ghana, Mexico, Russia, and South Africa) using nationally representative datasets. Methods: Cross-sectional, community-based data from the WHO Study on global AGEing and adult health (SAGE) were analyzed. Visual acuity was measured using the tumbling ElogMAR chart, and vision impairment (at distance and near) was defined as visual acuity worse than 6/18 (0.48 logMAR) in the better-seeing eye. The definition of MCI was based on the National Institute on Aging-Alzheimer’s Association criteria. Multivariable logistic regression was conducted. Results: Data on 32,715 individuals aged ≥ 50years [mean (SD) age 62.1 (15.6) years; 51.2% females] were analyzed. Compared to those without far or near vision impairment, those with near vision impairment but not far vision impairment (OR = 1.33; 95% CI = 1.16–1.52), and those with both far and near vision impairment (OR = 1.70; 95% CI = 1.27–2.29) had significantly higher odds for MCI. Only having far vision impairment was not significantly associated with MCI. Conclusions: Visual impairment is associated with increased odds for MCI among older adults in LMICs with the exception of far vision impairment only. Future longitudinal and intervention studies should examine causality and whether improvements in visual acuity, or early intervention, can reduce risk for MCI and ultimately, dementia. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG part of Springer Nature.

Background: Loneliness may be a risk factor for mild cognitive impairment but studies on this topic are scarce, particularly from low- and middle-income countries (LMICs). Therefore, the aim of the present study was to investigate the association between loneliness and mild cognitive impairment (MCI) in six LMICs (China, Ghana, India, Mexico, Russia and South Africa). Methods: Cross-sectional, community-based, nationally representative data from the WHO Study on global AGEing and adult health (SAGE) were analyzed. The definition of MCI was based on the National Institute on Ageing-Alzheimer's Association criteria. Multivariable logistic regression analysis and meta-analysis were conducted to assess associations. Results: The final analytical sample consisted of 19,092 and 13,623 individuals aged 50–64 years (middle-aged adults) and ≥65 years (older adults), respectively. Among the middle-aged, overall, loneliness was associated with a non-significant 1.43 (95% confidence interval [CI]=0.93–2.21) times higher odds for MCI although significant associations were observed in China (OR=1.51; 95%CI=1.08–2.09) and South Africa (OR=3.87; 95%CI=1.72–8.71). As for older adults, overall, there was a significant association between loneliness and MCI (OR=1.52; 95%CI=1.12–2.07). Conclusion: In this large representative sample of middle-aged and older adults from multiple LMICs, findings suggest that loneliness is associated with MCI. It may be prudent to consider reducing loneliness in low-economic settings to aid in the prevention of MCI and ultimately dementia.

Background-\ud \ud 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.\ud \ud Objective-\ud \ud To investigate the association between sleep problems and MCI in a large sample of adults from six low-and middle-income countries (LMICs).\ud \ud Design-\ud \ud Cross-sectional.\ud \ud Setting-\ud \ud Study on Global Ageing and Adult Health (SAGE).\ud \ud Subjects-\ud \ud 32,715 individuals aged ≥50 years with preservation in functional abilities [age range 50–114 years; 51.7% females].\ud \ud Methods-\ud \ud 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.\ud \ud Results-\ud \ud 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 between-country heterogeneity was observed (I2 = 28.2%).\ud \ud Conclusions-\ud \ud 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.

International audience; The cerebrospinal fluid (CSF) biochemical markers (biomarkers) Amyloidβ 42 (Aβ42), total Tau (T-tau) and Tau phosphorylated at threonine 181 (P-tau181) have proven diagnostic accuracy for mild cognitive impairment and dementia due to Alzheimer's Disease (AD). In an effort to improve the accuracy of an AD diagnosis, it is important to be able to distinguish between AD and other types of dementia (non-AD). The concentration ratio of Aβ42 to Aβ40 (Aβ42/40 Ratio) has been suggested to be superior to the concentration of Aβ42 alone when identifying patients with AD. This article reviews the available evidence on the use of the CSF Aβ42/40 ratio in the diagnosis of AD. Based on the body of evidence presented herein, it is the conclusion of the current working group that the CSF Aβ42/40 ratio, rather than the absolute value of CSF Aβ42, should be used when analysing CSF AD biomarkers to improve the percentage of appropriately diagnosed patients.