Abstract
This prospective longitudinal study investigated the 10-year trajectories of depressive symptoms and cognitive performance among formal-sector retirees in urban South Africa. Utilizing four waves of data collected between 2012 and 2022 from a cohort of 1,850 retirees aged 60 and older across Gauteng and the Western Cape, we applied parallel-process latent growth curve modeling to evaluate the bidirectional temporal relationships between depressive symptoms (measured via the Center for Epidemiologic Studies Depression Scale) and cognitive function (measured using a composite score of episodic memory and executive function). We identified three distinct latent trajectory classes: 'Resilient/Cognitive Stable' (61.2%), 'Escalating Depression/Moderate Cognitive Decline' (26.5%), and 'Persistent High Depression/Rapid Cognitive Decline' (12.3%). Higher baseline depressive symptoms significantly predicted accelerated cognitive decline over time (β = -0.34, p < 0.001), while lower baseline cognitive function was associated with an steeper increase in depressive symptoms (β = -0.22, p = 0.004). Socioeconomic stability through occupational pensions partially attenuated cognitive deterioration, whereas cardiovascular risk factors exacerbated dual-decline trajectories. These findings highlight a pronounced co-occurrence of late-life affective disorders and cognitive impairment in an understudied middle-income African setting. Integrating routine depression screening and cognitive assessments into primary geriatric care and post-retirement welfare frameworks is imperative for preserving functional independence among aging urban populations in South Africa.
