First stages chronic kidney disease have mild effects on cognitive performance. Results of a 15,105 brazilian adult baseline cohort.

INTRODUCTION: The aging of the population may lead to an increased prevalence of dementia and chronic kidney disease (CKD) and their overlap.

OBJECTIVE: We investigated the association between CKD and cognitive performance among Brazilian adults (35-74 years).

METHODS: Baseline data analysis of the Longitudinal Study of Adults (ELSA-Brasil), a multicenter cohort comprising 15,105 civil servants, was performed. Kidney function was defined by the CKD-Epi-estimated GRF and albumin creatinin ratio (ACR). Cognitive performance was measured across tests that included the word memory tests, verbal fluency tests and Trail Making Test B. Multiple logistic and linear regressions were used to investigate the association between CKD and global as well as test-specific lowered cognitive performance.

RESULTS: More than 90% of participants did not present CKD even considering reduced GFR or increased ACR simultaneously. Lowered cognitive performance was detected among 15.8% of the participants and mean values of GFR were slightly higher among those with normal than with lowered cognitive performance (86 ± 15 mL/min/1.73 m2 x 85 ± 16 mL/min/1.73 m2, p < 0.01). Age, education, skin-color, smoking, drinking, hypertension, and diabetes were associated with lowered cognition. After adjustment for these variables, there was no association between CKD and lowered cognitive performance. Negligibly small beta values were observed when analyzing CKD and the scores of all tests.

CONCLUSION: These results suggest that cognitive performance remains preserved until renal function reaches significant worsening. Preventive measures to maintain renal function may contribute to the preservation of cognitive function.