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Background and Purpose: Brain arterial diameters are markers of cerebrovascular disease. Demographic and anatomical factors may influence arterial diameters. We hypothesize that age, sex, height, total cranial volume (TCV), and persistent fetal posterior cerebral artery (fPCA) correlate with brain arterial diameters across populations., Methods: Participants had a time-of-flight MRA from nine international cohorts. Arterial diameters of the cavernous internal carotid arteries (ICA), middle cerebral arteries (MCA), and basilar artery (BA) were measured using LAVA software. Regression models assessed the association between exposures and brain arterial diameters., Results: We included 6,518 participants (mean age: 70 ± 9 years; 41% men). Unilateral fPCA was present in 13.2% and bilateral in 3.2%. Larger ICA, MCA, and BA diameters correlated with older age (Weighted average [WA] per 10 years: 0.18 mm, 0.11 mm, and 0.12 mm), male sex (WA: 0.24 mm, 0.13 mm, and 0.21 mm), and TCV (WA: for one TCV standard deviation: 0.24 mm, 0.29 mm, and 0.18 mm). Unilateral and bilateral fPCAs showed a positive correlation with ICA diameters (WA: 0.39 mm and 0.73 mm) and negative correlation with BA diameters (WA: -0.88 mm and -1.73 mm). Regression models including age, sex, TCV, and fPCA explained on average 15%, 13%, and 25% of the ICA, MCA, and BA diameter interindividual variation, respectively. Using height instead of TCV as a surrogate of head size decreased the R-squared by 3% on average., Conclusion: Brain arterial diameters correlated with age, sex, TCV, and fPCA. These factors should be considered when defining abnormal diameter cutoffs across populations., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objectives: Our study investigates measurement, correlates, and functional associations of vision impairment (VI) in an aging population in rural South Africa. Methods: 1582 participants aged 40-69 reported on near (NVI) and distance vision impairment (DVI) and completed objective vision tests. Logistic and linear regression were used to evaluate sociodemographic, health, and psychosocial correlates of VI and assess relationships between VI and cognitive and physical function. Results: VI prevalence was considerably higher according to objective testing (56%) versus self-reports (18%). Older adults were especially likely to underreport impairment. Objective VI was associated with age, education, cardiometabolic disease, and female sex. Conversely, self-reported VI was associated with psychosocial factors. Objective NVI and both types of DVI were associated with worse visual cognition and slower gait speed, respectively. Discussion: Self-reported and objective VI measures should not be used interchangeably in this context. Our findings highlight extensive burden of untreated VI in this region.

Objectives: We investigate how caregiving for grandchildren is associated with cognitive function among rural South Africans, and whether the association differs by gender. We further investigate whether measures of physical activity or social engagement mediate this association. Methods: Data were from interviews with 3668 Black, South African grandparents in the "Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa" study, conducted between 2014 and 2015. Results: We find that caregiving grandparents have better cognitive function than non-caregiving grandparents, and this association does not differ by grandparent gender. Although grandchild caregiving is associated with physical activity and social engagement measures, and some of these measures are associated with cognitive function, we do not find conclusive evidence of mediation. Discussion: Providing care for grandchildren may stimulate cognitive function for both grandmothers and grandfathers. Neither physical activity nor social engagement explains the association between caregiving and cognitive function.