Education modifies the relationship between height and cognitive function in a cross-sectional population-based study of older adults in Rural South Africa
We aimed to estimate the relationship between height (a measure of early-life cumulative net nutrition) and later-life cognitive function among older rural South African adults, and whether education modified this relationship. Data were from baseline in-person interviews with 5059 adults ≥ 40 years in the population-based “Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa” (HAALSI) study in Agincourt sub-district, South Africa, in 2015. Linear regression was used to estimate the relationship between height quintile and latent cognitive function z-score (representing episodic memory, time orientation, and numeracy), with adjustment for life course covariates and a height-by-education interaction. Mean (SD) height was 162.7 (8.9) cm. Nearly half the sample had no formal education (46%; 2307/5059). Mean age- and sex-adjusted cognitive z-scores increased from − 0.68 (95% CI: − 0.76 to − 0.61) in those with no education in the shortest height quintile to 0.62 (95% CI: 0.52–0.71) in those with at least 8 years of education in the tallest height quintile. There was a linear height disparity in cognitive z-scores for those with no formal education (adjusted β = 0.10; 95% CI: 0.08–0.13 per height quintile), but no height disparity in cognitive z-scores in those with any level of education. Short stature is associated with poor cognitive function and may be a risk factor for cognitive impairment among older adults living in rural South Africa. The height disparity in cognitive function was negated for older adults who had any level of education.
KeywordsCognitive function Older adults Education Height South Africa
This work was supported by the National Institute on Aging of the National Institutes of Health [Grant Number P01 AG041710]. The funder had no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the article; or in the decision to submit it for publication. The authors gratefully acknowledge Dr. Nikkil Sudharsanan for advice on the interpretation of data for this manuscript.
Compliance with ethical standards
Ethical approval was granted by the University of the Witwatersrand Human Research Ethics Committee (M141159), the Harvard T. H. Chan School of Public Health, Office of Human Research Administration (C13-1608-02), and the Mpumalanga Provincial Research and Ethics Committee. Informed consent was obtained from all individuals included in the study. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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