Chronic kidney disease and cognitive function in older adults: findings from the chronic renal insufficiency cohort cognitive study.

Objectives: To investigate cognitive impairment in older, ethnically diverse individuals with a broad range of kidney function, to evaluate a spectrum of cognitive domains, and to determine whether the relationship between chronic kidney disease (CKD) and cognitive function is independent of demographic and clinical factors.
Design: Cross-sectional.
Setting: Chronic Renal Insufficiency Cohort Study.
Participants: Eight hundred twenty-five adults aged 55 and older with CKD.
Measurements: Estimated glomerular filtration rate (eGFR, mL/min per 1.73 m(2)) was estimated using the four-variable Modification of Diet in Renal Disease equation. Cognitive scores on six cognitive tests were compared across eGFR strata using linear regression; multivariable logistic regression was used to examine level of CKD and clinically significant cognitive impairment (score < or =1 standard deviations from the mean).
Results: Mean age of the participants was 64.9, 50.4% were male, and 44.5% were black. After multivariable adjustment, participants with lower eGFR had lower cognitive scores on most cognitive domains (P<.05). In addition, participants with advanced CKD (eGFR<30) were more likely to have clinically significant cognitive impairment on global cognition (adjusted odds ratio (AOR) 2.0, 95% CI=1.1-3.9), naming (AOR=1.9, 95% CI=1.0-3.3), attention (AOR=2.4, 95% CI=1.3-4.5), executive function (AOR=2.5, 95% CI=1.9-4.4), and delayed memory (AOR=1.5, 95% CI=0.9-2.6) but not on category fluency (AOR=1.1, 95% CI=0.6-2.0) than those with mild to moderate CKD (eGFR 45-59).
Conclusion: In older adults with CKD, lower level of kidney function was associated with lower cognitive function on most domains. These results suggest that older patients with advanced CKD should be screened for cognitive impairment.