ELEVATED SERUM CREATININE LEVELS DIFFERENTIALLY IMPACT COGNITIVE FUNCTIONING AMONG MEXICAN AMERICAN ELDERS AND NON-HISPANIC WHITES: A PROJECT FRONTIER STUDY

Date

2014-03

Authors

Regina, Stephen P.
Johnson, Leigh

ORCID

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Abstract

Objective: Kidney function decreases with age and is commonly observed in the elderly. Even mildly decreased kidney function is associated with increased vascular disease and cerebrovascular disease, and is believed to influence risk of Alzheimer’s disease (AD). Mexican Americans are reported to exhibit a decreased serum creatinine (SCr) distribution relative to that of Non-Hispanic Whites . It has been suggested that blood-based measures of kidney function may have a predictive role in the future for identifying patients who may benefit from detailed cognitive screening . The aim of this study was to determine the effects of impaired renal function as assessed by elevated SCr on cognition among Mexican American and Non-Hispanic White elders. Method: Data were analyzed from 487 participants (n= 192, Mexican American; n= 295, Non-Hispanic White) enrolled in Project FRONTIER, a community-based study of health issues in rural-dwelling adults and elders. Cognition was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Serum creatinine was reported by CMP. Linear regressions were utilized to examine the relationships between decreased measures of cognitive functioning and ethnicity when SCr level is elevated. Results: Among those who are Non-Hispanic white, elevated SCr levels were associated with poorer performance on tasks related to immediate memory (RBANS Immediate Memory Index, B[SE]= -3.12[1.32], t=-2.36, p=0.019) and language (RBANS Language Index, B[SE]=-2.04[0.79], t= -2.56, p=0.011). Concerning those who were Hispanic and of Mexican American decent, elevated SCr levels were found to be significantly negative associated with attention (RBANS Attention Index, B[SE]= -4.57[2.18], t=-2.08, p=0.038) and executive functioning (EXIT25, B[SE]= 1.90[0.82], t=2.29, p=0.023). Conclusions: This study emphasizes the ethnic differences observed with elevated levels of serum creatinine, which is a marker of kidney function. The results supported a differential relationship between creatinine and cognitive functioning, implicating that among Non-Hispanic Whites, elevated levels were associated with decreased performance on tasks of memory and language; whereas, among Hispanic Mexican Americans, there was a relationship between decreased performance on tasks of attention and executive functioning with elevations in the level of creatinine in serum.

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