Association of cognitive function with albuminuria and eGFR in the general population

Abstract

Background and objectives: Recent studies found different associations of cognitive function with albuminuria or estimated GFR (eGFR). Most studies were limited to the elderly or did not take both renal variables into account. Therefore, this study analyzed the association of cognitive function with albuminuria and eGFR in community-dwelling persons aged 35 to 82 years.

Design, setting, participants, & measurements: This was a cross-sectional study comprising 4095 participants of the Prevention of Renal and Vascular End-Stage Disease (PREVEND) study. Cognitive function, measured with the Ruff Figural Fluency Test (RFFT), was treated as the dependent variable, and albuminuria and eGFR were treated as independent variables.

Results: The prevalence of albuminuria <10, 10 to 29, and ≥30 mg/24 h was 54%, 31%, and 15%, respectively. Mean eGFR (± SD) was 79 ± 15 ml/min per 1.73 m(2). Because of interaction between albuminuria and age, analyses were performed per age tertile. After multivariate adjustment, albuminuria ≥ 30 mg/24 h, but not eGFR, was associated with lower RFFT score in the youngest tertile (B -5.3; 95% CI, -0.6 to -9.2; P = 0.05), but not in older tertiles. Moreover, subjects in the youngest tertile with increasing albuminuria (5-15 and >15 mg/24 h) before RFFT measurement had lower mean RFFT scores than subjects with stable albuminuria: mean difference -4.9 (P = 0.3) and -6.7 (P = 0.03), respectively.

Conclusions: In this community-based cohort, elevated albuminuria was associated with worse cognitive function in young but not in old persons. There was no association of eGFR with cognitive function.

Figure 1.

Mean Ruff Figural Fluency Test (RFFT) score and its relationship with age and educational level.

Figure 2.

Mean RFFT score in subjects subdivided into clinical classes of albuminuria and estimated GFR (eGFR). Adjusted RFFT scores were calculated by analysis of covariance (ANCOVA) and adjusted for age, sex, educational level, diabetes mellitus, hypertension, history of cardiovascular disease, body mass index, alcohol use, cholesterol, and smoking. Bars represent 95% confidence intervals.

Figure 3.

Mean RFFT score and its relationship with the change in albuminuria (mg/24 h) between baseline (1997 to 1998) and the third survey (2000 to 2003) in subjects subdivided into tertiles of age. Adjusted RFFT scores were calculated by ANCOVA and adjusted for eGFR, age, sex, educational level, diabetes, hypertension, history of cardiovascular disease, body mass index, alcohol use, cholesterol, and smoking. Bars represent the 95% CIs of the mean RFFT score. *P < 0.05.