Original Study The Association Between Kidney Function and Cognitive Decline in Community-Dwelling, Elderly Japanese People SungChul Lee PhD a, *, Hiroyuki Shimada PhD, PT a , Hyuntae Park PhD a , Hyuma Makizako PhD, PT a , Sangyoon Lee PhD a , Takehiko Doi PhD, PT a, b , Daisuke Yoshida PhD, PT a , Kota Tsutsumimoto MSc, PT a , Yuya Anan MSc a , Takao Suzuki PhD, MD c a Department of Functioning Activation, Center for Gerontology and Social Science, National Center for Geriatrics and Gerontology, Obu, Japan b Japan Society for the Promotion of Science, Tokyo, Japan c Research Institute, National Center for Geriatrics and Gerontology, Obu, Japan Keywords: Chronic kidney disease creatinine decline in cognitive function abstract Objectives: The aim of this study was to evaluate the relationship between chronic kidney disease (CKD) and cognitive decline in community-dwelling older adults without dementia. Design: Cross-sectional. Setting: Obu Study of Health Promotion for the Elderly in Japan. Participants: The participants were 4686 residents (community-dwelling older adults without dementia) who completed baseline assessments. Measurements: The estimated glomerular filtration rate (eGFR, mL/min/1.73 m 2 ) was determined ac- cording to the creatinine level, and participants were classified into three mutually exclusive categories: normal (60.0 mL/min/1.73 m 2 ), mild CKD (45.0e59.9 mL/min/1.73 m 2 ), or moderate to severe CKD (<45.0 mL/min/1.73 m 2 ). Cognitive function was assessed using the National Center for Geriatrics and Gerontology-Functional Assessment Tool. Multivariate logistic regression was used to examine the re- lationships between eGFR and cognitive decline. Results: After multivariate adjustment, participants with lower eGFR had lower cognitive function scores on most domains (P < .05). In particular, participants with advanced CKD (eGFR <45 mL/min/1.73 m 2 ) were more likely to have significant cognitive decline on the Trail Making Test part A (odds ratio ¼ 2.347, 95% confidence interval ¼ 1.525e3.614) and the Symbol Digit Substitution Task (odds ratio ¼ 2.308, 95% confidence interval ¼ 1.486e3.585) than those with normal and mild CKD. Conclusions: A lower level of kidney function was associated with lower cognitive performance in attention and processing speed. These results suggest that eGFR might be an effective method to screen for cognitive decline in community-dwelling older adults. Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine. The prevalence of chronic kidney disease (CKD) in the general population has been predicted to be between 6.8% and more than one-fifth, 1e3 depending on the age and ethnicity of the target popu- lation. Similarly, cognitive decline is common in older adults. Both conditions are associated with greater healthcare use and poorer quality of life and are of increasing public health significance. 4,5 Prior studies examining CKD and cognitive function have reported an association of CKD with general cognitive function, incident de- mentia, and functioning cognitive abilities related to verbal learning, visual attention, mental flexibility, and executive functioning. 6e10 Seliger et al 11 demonstrated that older adults with CKD had a high- er risk for dementia than healthy older adults from the Cardiovascular Health Study. In the Healthy Aging and Body Composition study, 8 participants with estimated glomerular filtration rate (eGFR) below 60 mL/min/1.73 m 2 had lower baseline scores on the modified Mini- Mental State Examination (MMSE) compared with participants with eGFR above 60 mL/min/1.73 m 2 . Of the 886 older adults participating in the Rush Memory and Aging project, those with eGFR below 60 mL/min/1.73 m 2 experienced a faster decline in cognitive function, This study was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan. The authors declare no conflicts of interest. * Address correspondence to SungChul Lee, PhD, Department of Functioning Activation, Center for Gerontology and Social Science, National Center for Geriatrics and Gerontology, 35 Gengo, Morioka, Obu, Aichi 474-8511, Japan. E-mail address: leesuykr@gmail.com (S. Lee). JAMDA journal homepage: www.jamda.com http://dx.doi.org/10.1016/j.jamda.2014.12.009 1525-8610/Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine. JAMDA 16 (2015) 349.e1e349.e5