Relationship between Cognitive Impairment and Depression in Dialysis Patients

Purpose: Patients with chronic kidney disease frequently show cognitive dysfunction. The association of depression and cognitive function is not well known in maintenance dialysis patients. We evaluated cognitive impairment and depression, as well as their relationship in regards to methods of dialysis, maintenance hemodialysis (MHD) and chronic peritoneal dialysis (CPD). Materials and Methods: Fifty-six maintenance dialysis patients were recruited and their clinical and laboratory data were collected. The Korean version of the mini-mental state exam (K-MMSE) was applied to screen the patient's cognitive function, while the Korean version of the Beck Depression Inventory (K-BDI) was used for depression screening. Results: The average age of the participants was 54.2 +/- 10.2 years; 29 (51.8%) were female. The average dialysis vintage was 4.2 +/- 3.8 years. The CPD group showed significantly higher K-MMSE score (27.8 +/- 2.9 vs. 26.1 +/- 3.1, p=0.010) and lower K-BDI score (12.0 +/- 8.4 vs. 20.2 +/- 10.4, p=0.003) compared with the MHD group. The percentage of patients with depression symptoms was higher in the MHD group (51.7% vs. 18.5%). There was a negative correlation between cognitive function and prevalence of depressive symptoms. Depression and education level were shown to be independent predictors for cognitive impairment in multivariate analysis. Conclusion: Cognitive impairment was closely correlated with depression. It is important to detect cognitive impairment and depression early in maintenance dialysis patients with simple bedside screening tools.