Supplementary Material for: Mid-life household food insecurity and subsequent memory function and rate of decline in rural South Africa, 2004-2022

Introduction: We aimed to investigate mid-life food insecurity over time in relation to subsequent memory function and rate of decline in Agincourt, rural South Africa.
Methods: Data from the longitudinal Agincourt Health and Socio-Demographic Surveillance System (Agincourt HDSS) were linked to the population-representative Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa" (HAALSI). Food insecurity (yes vs. no) and food insecurity intensity (never/rarely/sometimes vs. often/very often) in the past month were assessed every 3 years from 2004-2013 in Agincourt HDSS. Cumulative exposure to each food insecurity measure was operationalized as 0, 1, and ≥2 time points. Episodic memory was assessed from 2014/15-2021/22 in HAALSI. Mixed-effects linear regression models were fitted to investigate the associations of each food insecurity measure with memory function and rate of decline over time.
Results: A total of 3,186 participants (mean age [SD] in 2004: 53 [12.87]; range: 30-96) were included and 1,173 (36%) participants experienced food insecurity in 2004, while this figure decreased to 490 (15%) in 2007, 489 (15%) in 2010, and 150 (5%) in 2013. Experiencing food insecurity at one time point (vs. never) from 2004-2013 was associated with lower baseline memory function (β=-0.095; 95% CI: -0.159 to -0.032) in 2014/15 but not rate of memory decline. Higher intensity of food insecurity at ≥ two time points (vs. never) was associated with lower baseline memory function (β =-0.154, 95% CI: -0.338 to 0.028), although the estimate was imprecise. Other frequencies of food insecurity and food insecurity intensity were not associated with memory function or decline in the fully adjusted models.
Conclusion: In this setting, mid-life food insecurity may be a risk factor for lower later-life memory function, but not decline.