<p>HIV status definition across survey waves.</p>

With the introduction of antiretroviral treatment (ART), life expectancy among people with HIV in South Africa has increased substantially. This ageing population faces age-related challenges, including cognitive decline. Yet, differences in cognitive trends between people with and without HIV remain poorly understood. We analyzed longitudinal data on 3,066 adults aged 40 + years in rural South Africa from the “Health and Aging in Africa: Longitudinal Studies in South Africa" (HAALSA) cohort. Using generalized estimating equations, we compared episodic memory trajectories over seven years (2014 – 2022) across three groups: (1) people without HIV, (2) people with HIV and suppressed viral load, and (3) people with HIV and unsuppressed viral load. Furthermore, we predicted episodic memory scores at yearly intervals. On average, the trend in episodic memory decline did not differ between people without HIV and people with HIV with suppressed or unsuppressed viral load. However, looking individually at yearly intervals revealed that participants without HIV experienced significantly steeper episodic memory decline compared to participants with HIV with suppressed viral load when controlling for individual-level characteristics. Consequently, over the seven-year period, participants without HIV progressed from having episodic memory comparable to those with suppressed viral load to levels similar to those with unsuppressed viral load. The slower episodic memory decline among virally suppressed people with HIV compared to those without HIV may reflect benefits from regular healthcare engagement or may also be a result of selective mortality. Our findings suggest that policymakers should: (1) intensify efforts to increase ART coverage and adherence among unsuppressed people with HIV; (2) implement targeted cognitive screening for at-risk individuals regardless of HIV status; (3) expand screening and treatment for conditions that contribute to cognitive decline; and (4) promote behaviors that may preserve cognitive function, particularly in resource-constrained settings. Further research on potential underlying mechanisms should be conducted.