Association between renal function and cognitive ability domains in the Einstein aging study: a cross-sectional analysis.
BACKGROUND
The relationships between renal function and specific domains of cognitive function have rarely been explored in representative, community-based samples of older adults. We assessed the association between renal and cognitive function based on an extensive battery of neurocognitive tests.


METHODS
In a sample of Einstein Aging Study participants (n = 649, age = 70+ years) we calculated estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration formula. We predefined three groups based on eGFR units of mL/min/1.73 m(2) as low (<45), medium (45-59), and high (≥60). Thirteen neurocognitive tests were subjected to principle component analysis revealing three components: a global component, an episodic memory component, and a frontal-executive component. We first examined the relationship of eGFR group to cognitive performance in each domain and then examined subtests for the domains which proved to be statistically significant.


RESULTS
The sample (mean = 79.2, 61% = female) was distributed among eGFR categories as follows: low (n = 67), medium (n = 151), and high (n = 431). The frontal-executive domain was significantly associated with poor cognitive performance in the low eGFR group (p <.001). When we examined the neuropsychological test components for frontal-executive domain, performance was lower on two of four contributing tests (Trail Making Test Part B and the Digit Symbol Substitution test). Other domains of cognitive function were not associated with eGFR.


CONCLUSIONS
Low eGFR is associated with reduced performance on executive function. Individuals with poor renal function should be assessed for cognitive impairment. Potential mechanisms are discussed.
Saul B. Korey Department of Neurology, the Einstein Aging Study, richard.lipton@einstein.yu.edu.
Andrea R
AR
Zammit
Saul B. Korey Department of Neurology, the Einstein Aging Study.
Mindy J
MJ
Katz
Department of Internal Medicine, Nephrology, University of Michigan, Ann Arbor.
Jennifer Y
JY
Lai
Saul B. Korey Department of Neurology, the Einstein Aging Study.
Molly E
ME
Zimmerman
Department of Internal Medicine, Nephrology, University of Michigan, Ann Arbor.
Markus
M
Bitzer
Richard B
RB
Lipton
D000368:Aged; D003072:Cognition Disorders / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D004522:Educational Status; D056344:Executive Function / Q000502:physiology*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D025341:Principal Component Analysis; D051437:Renal Insufficiency / Q000503:physiopathology*
Cognition; Executive function.; Renal function