Differential impact of age on verbal memory and executive functioning in chronic kidney disease

Abstract

We compared aspects of verbal memory and executive functioning in 51 community-dwelling persons with chronic kidney disease (CKD) and 55 healthy controls matched on age and education. Depressive symptoms were assessed with the Centre for Epidemiological Studies-Depression Scale (CES-D), and illness variables included glomerular filtration rate (GFR) and hemoglobin. Findings indicate that persons with CKD exhibited poorer performance on measures of memory (CVLT-II) and executive functioning (DKEFS Trailmaking Test B and Color-Word Interference Tests) in comparison with healthy controls. Furthermore, performance decrements were magnified in older CKD participants on measures of verbal memory and inhibition. Nearly half of CKD participants aged 61 and older exhibited significant impairments in verbal memory and inhibition in comparison to matched controls. Cognitive performance in CKD was not associated with measures of illness severity. The differences observed were not accounted for by depressive symptoms, which were only weakly associated with cognitive performance, and negatively associated with age. Findings highlight the need for further exploration of the etiologies and functional consequences of the neuropsychological presentation of CKD.