A Case-Control Study of Cognitive Function in Patients with End-Stage Renal Disease Before and After Hemodialysis in Southern Spain

BACKGROUND: Cognitive problems are frequent in patients with end-stage renal disease (ESRD) treated with hemodialysis. However, previous studies used only a single cognitive screening test or a small number of cognitive indices, which is inadequate for an exhaustive evaluation of cognitive deficits. This case-control study aimed to evaluate cognitive function in patients with ESRD before and after hemodialysis at centers in southern Spain, and included analysis of associations between cognitive function and duration of hemodialysis, biochemistry, body composition, and treatment variables. MATERIAL/METHODS: Cognitive performance was evaluated in 42 healthy participants (HPs) and in 43 ESRD patients, before and after hemodialysis. The tests measured verbal and visual memory, sustained/selective attention, and processing speed. The diagnostic criterion for ESRD was a glomerular filtration rate <15 mL/min/1.73 m(2). Correlation and multiple regression analyses were used to explore the relationships between cognitive and clinical variables, controlling for age, schooling, mood, and blood pressure. RESULTS: Scores for verbal memory, sustained/selective attention, and processing speed were lower in patients with ESRD treated with hemodialysis than in HPs, with no between-group differences in visual memory. No acute hemodialysis-specific effect on performance was observed. Several biochemistry variables were associated with performance, both negatively (eg total cholesterol, calcium, and total protein) and positively (eg sodium, phosphorus, and creatinine). CONCLUSIONS: Patients with ESRD treated with hemodialysis showed cognitive deficits in verbal memory, sustained/selective attention, and processing speed. Performance was not significantly different between tests administered before and after hemodialysis. An adequate diet as well as physical exercise could be useful to improve cognitive performance in this population.