Chronic kidney disease and cognitive impairment: a systematic review and meta-analysis.

BACKGROUND Chronic kidney disease (CKD) has emerged as a possible new risk factor of cognitive impairment and dementia, but results of studies remain conflicting. METHODS A systematic literature research of electronic databases (MEDLINE, Cochrane Library and Goggle Scholar covering the period from 1980 to January 2012) and meta-analysis of relevant cross-sectional and longitudinal studies were conducted to assess the association of CKD and cognitive decline. RESULTS Most cross-sectional and longitudinal studies suggest an association between cognitive impairment and CKD. Meta-analysis of cross-sectional and longitudinal studies comprising 54,779 participants yielded an association of cognitive decline in patients with CKD compared with patients without CKD (OR 1.65, 95% CI 1.32-2.05; p < 0.001, and OR 1.39, 95% CI 1.15-1.68; p < 0.001, respectively). CONCLUSION This is the first meta-analysis assessing the impact of CKD on cognitive decline. Our results suggest CKD being a significant and independent somatic risk factor in the development of cognitive decline.