Chronic kidney disease (CKD) is a significant risk factor for cognitive impairment — when a person has trouble concentrating, remembering, or making decisions. Previous studies have examined differences in cognitive impairment between those with and without kidney disease using multiple cognitive outcomes, but few have done this for an extensive battery of cognitive tests.
In recent studies, researchers working with the Maine-Syracuse Longitudinal Study (MSLS), a 35-year a community-based study of cardiovascular risk factors (CVD-RFs) and cognitive function, have discussed two important points: First, the proper comparison group for people with end-stage renal disease (ESRD) is a group of individuals with early-stage kidney disease, not healthy individuals free from the cardiovascular disease risk factors that play a role in the development of CKD and cognitive impairment.
Second, there is a lack of normative data on multiple assessments of cognitive function that would allow researchers to perform comparisons between chronic kidney disease and end-stage renal disease.
In a new study published in the journal Nephrology Dialysis Transplantation and titled “Risk for cognitive impairment across 22 measures of cognitive ability in early-stage chronic kidney disease,” researchers at the University of Maine, Temple University, and the University of Maryland revealed normative data for MSLS participants with early-stage chronic kidney disease that will allow clinicians to select the most appropriate tests for their patients’ needs.
This data will hopefully allow scientists to compare the cognitive functioning of study participants with end-stage renal disease with that of an appropriate reference group.
The study was community-based and cross-sectional and included 898 individuals free from dementia and end-stage renal disease. Estimated glomerular filtration rate (eGFR) was calculated using the chronic kidney disease epidemiology collaboration equation and classified as less than 60 or greater than 60mL/min/1,73 m2, based on consensus definitions of Stage 3 or greater CKD.
The results revealed that 146 individuals (16.3 percent) had eGFR less than 60 or greater than 60mL/min/1,73 m2 in the CKD group. Compared to participants without chronic kidney disease, those in the CKD group had a higher prevalence of CVD-RFs (25 percent vs. 12 percent) and diabetes mellitus (25 percent vs. 12 percent), suggesting that CVD-RFs related to kidney disease, such as inflammation, may play a role in the relationship between kidney disease and cognition.
Upon adjusting for these and other comorbidity-related risk factors, participants with early-stage CKD had a significantly greater risk for modestly impaired abilities in the scanning and tracking and visual-spatial organization and memory (VSOM) domains, as well as greater risk for severely impaired functioning in language.
“Targeted screening for cognitive deficits in kidney disease patients early in their disease course may be warranted,” the researchers wrote.