Long-term household material socioeconomic resources and cognitive health in a population-based cohort of older adults in rural northeast South Africa, 2001-2015

Lindsay C Kobayashi; Chodziwadziwa Whiteson Kabudula; Mohammed U Kabeto; Xuexin Yu; Stephen M Tollman; Kathleen Kahn; Lisa F Berkman; Molly S Rosenberg

doi:10.1016/j.ssmph.2022.101263

Long-term household material socioeconomic resources and cognitive health in a population-based cohort of older adults in rural northeast South Africa, 2001-2015

SSM Popul Health. 2022 Oct 10:20:101263. doi: 10.1016/j.ssmph.2022.101263. eCollection 2022 Dec.

Authors

Lindsay C Kobayashi^{1

2}, Chodziwadziwa Whiteson Kabudula², Mohammed U Kabeto³, Xuexin Yu¹, Stephen M Tollman^{2

4}, Kathleen Kahn^{2

4}, Lisa F Berkman^{2

5}, Molly S Rosenberg^{2

6}

Affiliations

¹ Center for Social Epidemiology and Population Health, Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, United States.
² MRC/Wits Rural Public Health & Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
³ Department of Internal Medicine, University of Michigan, Ann Arbor, MI, United States.
⁴ International Network for the Demographic Evaluation of Populations and Their Health (INDEPTH), Accra, Ghana.
⁵ Harvard Center for Population and Development Studies, Harvard T.H. Chan School of Public Health, Cambridge, MA, United States.
⁶ Department of Epidemiology and Biostatistics, Indiana University School of Public Health-Bloomington, Bloomington, IN, United States.

Abstract

Material resources owned by households that affect daily living conditions may be salient for cognitive health during aging, especially in low-income settings, but there is scarce evidence on this topic. We investigated relationships between long-term trends in household material resources and cognitive function among older adults in a population-representative study in rural South Africa. Data were from baseline interviews with 4580 adults aged ≥40 in "Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa" (HAALSI) in 2014/2015 linked to retrospective records on their household material resources from the Agincourt Health and Socio-Demographic Surveillance System (HDSS) from 2001 to 2013. Household material resources were assessed biennially in the Agincourt HDSS using a five-point index that captured dwelling materials, water and sanitation, sources of power, livestock, and technological amenities. Cognitive function was assessed in HAALSI and analyzed as a z-standardized latent variable capturing time orientation, episodic memory, and numeracy. We evaluated the relationships between quintiles of each of the mean resource index score, volatility in resource index score, and change in resource index score and subsequent cognitive function, overall and by resource type. Higher mean household resources were positively associated with cognitive function (β_adj = 0.237 standard deviation [SD] units for the highest vs. lowest quintile of mean resource index score; 95% CI: 0.163-0.312; p-trend<0.0001), as were larger improvements over time in household resources (β_adj = 0.122 SD units for the highest vs. lowest quintile of change in resources; 95% CI: 0.040-0.205; p-trend = 0.001). Results were robust to sensitivity analyses assessing heterogeneity by age and restricting to those with formal education. The findings were largely driven by technological amenities including refrigerators, stoves, telephones, televisions, and vehicles. These amenities may support cognitive function through improving nutrition and providing opportunities for cognitive stimulation through transportation and social contact outside of the home.

Grants and funding

R01 AG069128/AG/NIA NIH HHS/United States