BACKGROUND:Sugar-sweetened beverages (SSB) and artificially-sweetened beverages (ASB) have been inconsistently associated with declines in cognitive function. Because of their low caloric content and replacement of sugar, ASB are often seen as 'healthy' alternatives to SSB. OBJECTIVE:We longitudinally assessed the association between the consumption of SSB or ASB and cognitive function. DESIGN:A subsample of the 'Seguimiento Universidad de Navarra' (SUN) cohort of university graduates aged over 55 years old was evaluated with the Spanish Telephone Interview for Cognitive Status (STICS-m) at two-time points, separated by 6 years. Consumption of SSB and ASB was appraised using a validated food-frequency questionnaire. Linear regression models were fitted, adjusting for potential confounders, including cardiometabolic variables, with the change in the STICS-m score at year 6 as the dependent variable. RESULTS:A significant association between the consumption of SSB and changes in cognitive function as measured by the STICS-m was observed in the total sample, with a change of -0.43 (95% CI -0.85, -0.02, p = 0.04) in those that consumed >1 beverage/month compared to never/seldom consumers. The association was not significant for the consumption of ASB, but point estimates showed negative values, suggesting declines in cognition. CONCLUSIONS:Only the consumption of SSB, but not ASB, was significantly associated with a decline in cognitive function after 6 years. Further longitudinal studies are needed to explore the relationship between these beverages and cognitive function and the potential mechanisms through which they might be harmful.