Abstract
BackgroundIt is uncertain whether switching to frequent nocturnal hemodialysis improves cognitive function in well-dialyzed patients and how this compares to patients who receive a kidney transplant.MethodsWe conducted a multicenter observational study with longitudinal follow-up of the effect on cognitive performance of switching dialysis treatment modality from conventional thrice-weekly hemodialysis to frequent nocturnal hemodialysis, a functioning renal transplant or remaining on thrice-weekly conventional hemodialysis. Neuropsychological tests of memory, attention, psychomotor processing speed, executive function and fluency as well as measures of solute clearance were performed at baseline and again after switching modality. The change in cognitive performance measured by neuropsychological tests assessing multiple cognitive domains at baseline, 4 and 12 months after switching dialysis modality were analyzed using a linear mixed model.ResultsSeventy-seven patients were enrolled; 21 of these 77 patients were recruited from the randomized Frequent Hemodialysis Network (FHN) Nocturnal Trial. Of these, 18 patients started frequent nocturnal hemodialysis, 28 patients received a kidney transplant and 31 patients remained on conventional thrice-weekly hemodialysis. Forty-eight patients (62 %) returned for the 12-month follow-up. Despite a significant improvement in solute clearance, 12 months treatment with frequent nocturnal hemodialysis was not associated with substantial improvement in cognitive performance. By contrast, renal transplantation, which led to near normalization of solute clearance was associated with clinically relevant and significant improvements in verbal learning and memory with a trend towards improvements in psychomotor processing speed. Cognitive performance in patients on conventional hemodialysis remained stable with the exception of an improvement in psychomotor processing speed and a decline in verbal fluency.ConclusionsIn patients on conventional thrice-weekly hemodialysis, receiving a functioning renal transplant was associated with improvement in auditory-verbal memory and psychomotor processing speed, which was not observed after 12 months of frequent nocturnal hemodialysis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-016-0223-9) contains supplementary material, which is available to authorized users.
Highlights
It is uncertain whether switching to frequent nocturnal hemodialysis improves cognitive function in well-dialyzed patients and how this compares to patients who receive a kidney transplant
A total of 18 patients underwent frequent nocturnal hemodialysis, 28 patients underwent kidney transplantation and 31 patients remained on conventional thrice-weekly hemodialysis
Renal transplantation, which led to near normalization of creatinine clearance, normalization of serum phosphorus and correction of anemia was associated with significant improvements in memory and learning with a trend towards improvement in psychomotor processing speed
Summary
It is uncertain whether switching to frequent nocturnal hemodialysis improves cognitive function in well-dialyzed patients and how this compares to patients who receive a kidney transplant. Cognitive function is impaired in people with chronic kidney disease (CKD) and correlates with the degree of kidney dysfunction [1]. The etiology of cognitive dysfunction in patients with CKD is multifactorial including the uremic environment, fluid shifts with dialysis, anemia, medications, depression, acute illness and structural lesions in the brain associated with progressive vascular disease [4,5,6]. Previous studies have shown that renal replacement therapy with dialysis or transplantation is associated with improvement in cognitive function [7,8,9]. Patients who receive a renal transplant have been reported to achieve cognitive function close to normal controls [10]. Recent studies have suggested that much of this cognitive dysfunction is associated with vascular disease and may not be reversible with further increases in solute clearance [13, 15, 16]
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