Kidney disease and cognitive function.

UNLABELLED: We provide a brief review of research on chronic kidney disease and cognitive performance, including dementia. We touch briefly on the literature relating end-stage-renal disease to cognitive function, but focus on studies of modest and moderate forms of chronic kidney disease (CKD) that precede dialysis and transplantation. We summarize previous reviews dealing with case control studies of patients but more fully examine community-based studies with large samples and necessary controls for demographic risk factors, cardiovascular variables, and other confounds such as depression. In addition we suggest potential biological and social-psychological mediators between CKD and cognition. Studies follow in two categories of design: (1) cross-sectional studies, and (2) longitudinal studies. In each, CKD is related to a wide range of deficits in cognitive functioning including verbal and visual memory and organization, and components of executive functioning and fluid intellect. In general, prior to the need to treat with hemodialysis (HD) or kidney transplant (KT), magnitude of effect with relation to CKD and function are small or modest in persons free from acute stroke and dementia. However, HD and KT can result in major impairment. We discuss needed controls, the greater demand on controls after the start of HD and KT, and suggest that mechanisms intervening relations between hypertension, or diabetes, and cognitive performance may be similar to those intervening between hypertension and cognitive performance and the hypertension and diabetes literature on cognition provides a good model for the study of early stage kidney disease and cognitive ability. We posit that the mechanisms linking CKD and cognition may be similar to those linking hypertension or diabetes to cognition. We identify the need for more studies with multiple cognitive test batteries, measures of every-day cognitive abilities relevant to patient understanding of the disease and treatments, and more studies with prevalent and incident dementia outcomes.

DESCRIPTORS: kidney disease, chronic kidney disease, cognitive function, dementia and cardiovascular risk factors.