Is kidney function associated with cognition and mood in late life?

Background: Chronic kidney disease (CKD), cognitive impairment and depression share common risk factors. Previous studies did not investigate the possible association between kidney function and cognitive and mood disorders in older persons in a broad range of kidney function. The present study explored associations between kidney function, cognition and mood in outpatients of 75 years and over. Methods: Baseline data of 2252 participants of the SCOPE study, an international multicenter cohort observational study,were used in which community-dwelling persons of 75 years and over were enrolled to screen for CKD Kidney function was estimated with the BIS1-eGFR equation, cognition was assessed with the Mini-Mental State Examination (MMSE) and mood with the Geriatric Depression Scale 15 items (GDS-15). Characteristics were compared across stages of CKD. Mean eGFR values were also compared across categories of MMSE (< 24, 24-26, ≥27) and between groups with high and low score on the GDS-15 (> 5/≤5). Results: In total, 63% of the population had an eGFR < 60 mL/min. In advanced stages of CKD, participants were older and more often men than in earlier stages (p < 0.001). Cardiovascular diseases and diabetes mellitus were more often found in those in advanced stages of CKD (p < 0.001), and also cumulative comorbidity scores were higher than in those in earlier stages (p < 0.001). Median MMSE was 29 in CKD stage 1-2 and 3, and 30 in CKD stage 4, whereas median GDS-15 score was 2 in all stages of CKD. Mean values of eGFR did not differ across categories of MMSE or between groups with high and low score on the GDS-15. Stratification for albuminuria did not change these results. Conclusions: Older persons in more advanced stages of CKD did not have lower cognitive scores or higher rates of depressive symptoms than older persons in earlier stages. Future longitudinal studies might give information on the possible effect of kidney function on cognition and mood in late life. Trial registration: This study was registered prospectively on 25th February 2016 at clinicaltrials.gov (NCT02691546).