Depression and Cognitive Function in Maintenance Hemodialysis Patients

Background: Both depression and cognitive impairment are common in hemodialysis patients, are associated with adverse clinical outcomes, and place an increased burden on health care resources. Study Design: Cross-sectional cohort. Setting & Participants: 241 maintenance hemodialysis patients in the Boston, MA, area. Predictor: Depressive symptoms, defined as a Center for Epidemiological Studies Depression Scale (CES-D) score >= 16. Outcome: Performance on a detailed neurocognitive battery. Results: Mean age was 63.8 years, 49.0% were women, 21.6% were African American, and median dialysis therapy duration was 13.8 months. There were 57 (23.7%) participants with significant depressive symptoms. In multivariable analysis adjusting for age, sex, education, and other comorbid conditions, participants with and without depressive symptoms performed similarly on the Mini-Mental State Examination (P = 0.4) and tests of memory. However, participants with greater depressive symptoms performed significantly worse on tests assessing processing speed, attention, and executive function, including Trail Making Test B (P = 0.02) and Digit-Symbol Coding (P = 0.01). Defining depression using a CES-D score >= 18 did not substantially change results. Limitations: Cross-sectional design, absence of brain imaging. Conclusions: Hemodialysis patients with a greater burden of depressive symptoms perform worse on tests of cognition related to processing speed and executive function. Further research is needed to assess the effects of treating depressive symptoms on cognitive performance in dialysis patients. Am J Kidney Dis 56: 704-712. (C) 2010 by the National Kidney Foundation, Inc.