Introduction and Aims: In older individuals reduced estimated glomerular filtration rate (eGFR) and (micro)albuminuria have been associated with worse cognitive performance. Data on the association between kidney function and cognitive performance in middle-aged individuals are scarce. We examined associations of eGFR and (micro)albuminuria with several domains of cognitive performance in a population-based cohort of middle-aged and older individuals.
Methods: Memory function, information processing speed and executive function were assessed in The Maastricht Study (n=2989). GFR was estimated by the CKD-EPI creatinine-cystatin C equation (eGFRcrcys). Urinary albumin excretion (UAE) was based upon two 24h urine collections. We examined cross-sectional associations of eGFRcrcys and (micro)albuminuria with cognitive performance with linear regression analyses. These analyses were adjusted for demographics, lifestyle factors and cardiovascular disease risk factors. Additionally, we tested whether these associations were mutually independent and for any interaction with age.
Results: Average age was 59.6 ±8.2 years, 51.1% were men and 26.5% had type 2 diabetes (design). UAE was <15 mg/24h in 81.6% of the population, 15-30 mg/24h in 10.3% and ≥30 mg/24h in 8.0%. After adjustment, with UAE <15 mg/24h as reference category, UAE 15-30 mg/24h was not associated with any of the domains of cognitive performance, whereas UAE ≥30 mg/24h was associated with lower information processing speed (beta (95%CI) -0.113 (-0.202; -0.025)). Average eGFRcrcys was 88.4±14.6 ml/min/1.73m2. After adjustment, eGFRcrcys was not associated with any of the domains of cognitive performance. Interaction analyses, however, suggested that the association between eGFRcrcys and cognitive performance was stronger in older individuals (Pinteraction < 0.05), e.g. for memory function, the beta (95%CI) was 0.009 (-0.025; 0.043) for 50-year-old individuals and -0.031 (-0.063; 0.001) for 70-year-old individuals after adjustment.
Conclusions: (Micro)albuminuria was independently associated with lower information processing speed and may thereby be a biomarker for cognitive decline. Mildly to moderately reduced eGFRcrcys was not associated with cognitive performance until older age.