Albuminuria, Cognitive Functioning, and White Matter Hyperintensities in Homebound Elders
Received 27 May 2008; accepted 15 August 2008. published online 15 December 2008.
Background
Albuminuria, a kidney marker of microvascular disease, may herald microvascular disease elsewhere, including in the brain.
Study Design
Cross sectional.
Setting & Participants
Boston, MA, elders receiving home health services to maintain independent living who consented to brain magnetic resonance imaging.
Predictor
Urine albumin-creatinine ratio (ACR).
Outcome
Performance on a cognitive battery assessing executive function and memory by using principal components analysis and white matter hyperintensity volume on brain imaging, evaluated in logistic and linear regression models.
Results
In 335 participants, mean age was 73.4 ± 8.1 years and 123 participants had microalbuminuria or macroalbuminuria. Each doubling of ACR was associated with worse executive function (β = −0.05; P = 0.005 in univariate and β = −0.07; P = 0.004 in multivariable analyses controlling for age, sex, race, education, diabetes, cardiovascular disease, hypertension, medications, and estimated glomerular filtration rate [eGFR]), but not with worse memory or working memory. Individuals with microalbuminuria or macroalbuminuria were more likely to be in the lower versus the highest tertile of executive functioning (odds ratio, 1.18; 95% confidence interval, 1.06 to 1.32; odds ratio, 1.19; 95% confidence interval, 1.05 to 1.35 per doubling of ACR in univariate and multivariable analyses, respectively). Albuminuria was associated with qualitative white matter hyperintensity grade (odds ratio, 1.13; 95% confidence interval, 1.02 to 1.25; odds ratio, 1.15; 95% confidence interval, 1.02 to 1.29 per doubling of ACR) in univariate and multivariable analyses and with quantitative white matter hyperintensity volume (β = 0.11; P = 0.007; β = 0.10; P = 0.01) in univariate and multivariable analyses of log-transformed data. Results were similar when excluding individuals with macroalbuminuria.
Limitations
Single measurement of ACR, indirect creatinine calibration, and reliance on participant recall for elements of medical history.
Conclusions
Albuminuria is associated with worse cognitive performance, particularly in executive functioning, as well as increased white matter hyperintensity volume. Albuminuria likely identifies greater brain microvascular disease burden.
1Division of Nephrology, Tufts Medical Center, Boston, MA
2Division of Medicine, Tufts Medical Center, Boston, MA
3Division of Psychiatry, Tufts Medical Center, Boston, MA
4Biostatistics Research Center, Tufts Medical Center, Boston, MA
5Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA
Address correspondence to Daniel E. Weiner, MD, MS, Division of Nephrology, Box #391, Tufts Medical Center, 800 Washington St, Boston, MA 02111
Because an author of this manuscript is an editor for AJKD, the peer-review and decision-making processes were handled entirely by an Associate Editor (Katherine Tuttle, MD, Sacred Heart Medical Center) who served as Acting Editor-in-Chief. Details of the journal's procedures for potential editor conflicts are given in the Editorial Policies section of the AJKD website.
ABSTRACT