Volume 7 Issue 3 • 1000331 J Alzheimers Dis Parkinsonism, an open access journal ISSN: 2161-0460 Open Access Mini Review Gronewold and Hermann, J Alzheimers Dis Parkinsonism 2017, 7:3 DOI: 10.4172/2161-0460.1000331 Journal of Alzheimer’s Disease & Parkinsonism J o u r n a l o f A l z h e i m e r s D i s e a s e & P a r k i n s o n i s m ISSN: 2161-0460 *Corresponding author: Dirk M Hermann, Department of Neurology, University Hospital Essen, Essen, Germany, Tel: 00491738619678; E-mail: dirk.hermann@uk-essen.de Received May 19, 2017; Accepted May 29, 2017; Published June 05, 2017 Citation: Gronewold J, Hermann DM (2017) Cognitive Impairment in Chronic Kidney Disease-Prevalence, Mechanisms and Consequences. J Alzheimers Dis Parkinsonism 7: 331. doi: 10.4172/2161-0460.1000331 Copyright: © 2017 Gronewold J, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Keywords: Chronic kidney disease; Cognitive impairment; Cerebral microangiopathy; Cerebral small vessel disease; Vascular risk factors; Dialysis Introduction Due to consistently low birth rates and increasing life expectancy in industrialized countries [1], age-related diseases like chronic kidney disease (CKD) get an increasing health problem worldwide [2,3]. CKD is linked to age-related renal function decline which is accelerated in comorbid conditions like hypertension, diabetes and obesity [4,5]. Regarding consequences of CKD, most studies concentrate on cardiovascular morbidity and mortality [6], while cognitive function, which is an important determinant of adherence to CKD therapy, is ofen overlooked [7]. Cognitive impairment in CKD is getting an increasingly relevant topic for healthcare systems, since CKD prevalence worldwide is estimated to be about 12% [8] and cognitive impairment to afect 17% to 87% of CKD patients, depending on CKD severity [7,9-15]. Prevalence of Chronic Kidney Disease CKD is diagnosed by indicators of kidney damage as well as indicators of decreased kidney function. Kidney damage is revealed by imaging or proteinuria that is mostly assessed by albumin to creatinine ratio (ACR) while kidney function is evaluated by glomerular fltration rate (GFR). GFR is usually estimated (eGFR) using serum creatinine concentrations by means of diferent equations of which the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation [16] should be preferred over the Modifcation of Diet in Renal Disease (MDRD) equation [17] according to current recommendations by the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) guideline for evaluation, classifcation, and stratifcation of chronic kidney disease [18]. In specifc cases, GFR should additionally be estimated from serum cystatin to confrm CKD diagnosis [18]. Based on eGFR and ACR, severity of CKD is classifed according to stages [18]. Stratifed by stages, global prevalence of CKD is 3.5% for stage 1 (eGFR>90 ml/min/1.73 m 2 +ACR>30), 3.9% for stage 2 (eGFR 60–89+ACR>30), 7.6% for stage 3 (eGFR 30–59), 0.4% for stage 4 (eGFR 29–15) and 0.1% for stage 5 (eGFR<15) [8]. Consequently, healthcare systems are mostly afected by the rather mild CKD stage 3, which due to an increase in CKD prevalence of 0.4% per year from the age of 30 years [8] is further highly prevalent in elderly people with about 35% of people over 70 years sufering from CKD stage 3 [19]. Stage 3 represents an important cutof for CKD patient care since these patients should be included in a CKD register and monitored at least once per year [18]. Early stages of CKD like stage 3 are ofen asymptomatic and thus not diagnosed early enough for prevention or delay of progression to more severe stages [5]. Interestingly, patients with early stages of CKD already show cognitive impairment [20]. Depending on CKD stage, CKD is frequently associated with prevalence of cognitive impairment in diferent domains including executive function, information processing speed, memory and language, which range from 17% to 87% [7,9-15]. Prevalence of Cognitive Impairment in Chronic Kidney Disease Cross-sectional studies are able to evaluate the prevalence of cognitive impairment in CKD. However, it is also of high clinical relevance to understand mutual links between CKD and cognitive impairment to develop strategies that allow us to prevent or delay cognitive decline. For that purpose, longitudinal studies are needed. So far, the majority of longitudinal studies reported decline in cognitive performance in CKD patients [21]. Unfortunately, in most of the previously published longitudinal studies, the association between CKD and cognitive performance over time was not the primary focus, thus participants were recruited outside hospital environments and only partly sufered from CKD. Further, mostly short screening tools like the Mini-Mental State Examination (MMSE) test or telephone interviews were used to assess cognitive performance which does not allow evaluating mild cognitive defcits and diferent domains. In addition, there is a problem with the selection of an adequate control group to evaluate cognitive Abstract In ageing populations, chronic kidney disease (CKD) gets an increasing health problem worldwide. While current therapy of CKD mostly focusses on kidney function and cardiovascular comorbidity, cognition, which crucially infuences adherence to CKD therapy, is often neglected. Prevalence of cognitive impairment is high in CKD, ranging from 17% to 87%, depending on CKD severity and cognitive domain affected. In contrast to Alzheimer’s disease patients, which often show impairment in memory function, CKD patients present with a broader spectrum of cognitive defcits, namely impairment in executive function, information processing, language and visuoconstruction which is usually mild in early CKD stages but advances with CKD progression and progression of comorbidities. Mechanisms underlying cognitive impairment in CKD are discussed and conclusions are derived how cognitive impairment may be prevented in CKD and, if cognitive defcits are present, how cognitive impairment may be taken into consideration in patient management. Cognitive Impairment in Chronic Kidney Disease-Prevalence, Mechanisms and Consequences Janine Gronewold and Dirk M Hermann* Department of Neurology, University Hospital Essen, Essen, Germany