A new approach for cognitive impairment pattern in chronic kidney disease

Chronic kidney disease (CKD) is associated with an elevated risk of neurocognitive disorders (NCDs). It remains unclear whether CKD-related NCDs have a specific cognitive pattern or are earlier-onset phenotypes of the main NCDs (vascular NCDs and Alzheimer's disease).

We used the Mini Mental State Examination score (MMSE) to assess cognitive patterns in 3003 CKD patients (stage 3-4) followed up over 5 years in the Chronic Kidney Disease-Renal Epidemiology and Information Network (CKD-REIN) cohort. After normalizing MMSE scores to a 0-to-100 scale, the associations between the baseline estimated glomerular filtration rate (eGFR, using the Chronic Kidney Disease Epidemiology Collaboration creatinine formula) and changes in each MMSE domain score were assessed in linear mixed models.

Patients (age: 67 ± 13 years old; males: 65%, mean eGFR: 33± 12 mL/min/1.73 m2) had a good baseline cognitive functions: the mean MMSE score was 26.9/30 ± 2.9. After adjustment for age, sex, educational level, depression (past or present), cardiovascular risk factors and cerebrovascular disease, a lower baseline eGFR (per 10 mL/min/1.73 m2) was associated with a 0.53-point decrement [P < .001; 95% confidence interval (CI) (-0.98, -0.08)] for orientation, a 1.04-point decrement [P = .03; 95% CI (-1.96, -0.13)] for attention and calculation, a 0.78-point decrement [P = .003; 95% CI (-1.30, -0.27)] for language, and a 0.94-point decrement [P = .02; 95% CI (-1.75, -0.13)] for praxis. Baseline eGFR was not, however, associated with significant changes over time in MMSE domain scores.

A lower eGFR in CKD patients was associated with early impairments in certain cognitive domains: praxis, language and attention domains before an obvious cognitive decline. Early detection of NCD in CKD patients must be performed before clinically cognitive decline using preferably tests assessing executive, attentional functions and language, rather than memory tests. This early cognitive screening could lead to a better management of cognitive impairment and their consequences on CKD management.