title: Cognitive changes associated with switching to frequent nocturnal hemodialysis or renal transplantation.
abstract: BACKGROUND
  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.
  
  
  METHODS
  We 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.
  
  
  RESULTS
  Seventy-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.
  
  
  CONCLUSIONS
  In 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.
authors.affiliation: Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA, USA. bradley-dixon@uiowa.edu.|Veterans Administration Medical Center, Iowa City, IA, USA. bradley-dixon@uiowa.edu.|Nephrology Division, University of Iowa School of Medicine, E300D GH, 200 Hawkins Drive, Iowa City, IA, 52242-1081, USA. bradley-dixon@uiowa.edu.
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Dixon
authors.affiliation: Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA, USA. john-vanburen@uiowa.edu.
authors.forename: John M
authors.initials: JM
authors.lastname: VanBuren
authors.affiliation: Center for Transplant Outcomes and Quality Improvement, The Transplant Institute, Beth Israel Deaconess Medical Center and the Harvard Medical School, Boston, MA, USA. jrrodrig@bidmc.harvard.edu.
authors.forename: James R
authors.initials: JR
authors.lastname: Rodrigue
authors.affiliation: Department of Internal Medicine, University of Virginia Health System, Charlottesville, VA, USA. boblockridge@gmail.com.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Lockridge
authors.affiliation: Department of Medicine, The University of Western Ontario, London, ON, Canada. robert.lindsay@lhsc.on.ca.
authors.forename: Robert
authors.initials: R
authors.lastname: Lindsay
authors.affiliation: Department of Medicine, University of Toronto, University Health Network, Toronto, ON, Canada. christopher.Chan@uhn.ca.
authors.forename: Christopher
authors.initials: C
authors.lastname: Chan
authors.affiliation: Department of Medicine, Wake Forest School of Medicine , Winston-Salem, NC, USA. mrocco@wakehealth.edu.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Rocco
authors.affiliation: Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA, USA. jacob-oleson@uiowa.edu.
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Oleson
authors.affiliation: Departments of Psychiatry, Neurology and Psychology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA. leigh-beglinger@uiowa.edu.
authors.forename: Leigh
authors.initials: L
authors.lastname: Beglinger
authors.affiliation: Departments of Psychology and Neurology, University of Utah, Salt Lake City, UT, USA. kevin.duff@hsc.utah.edu.
authors.forename: Kevin
authors.initials: K
authors.lastname: Duff
authors.affiliation: Departments of Psychiatry, Neurology and Psychology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA. jane-paulsen@uiowa.edu.
authors.forename: Jane S
authors.initials: JS
authors.lastname: Paulsen
authors.forename: John B
authors.initials: JB
authors.lastname: Stokes
mesh_terms: D000328:Adult; D001288:Attention; D003071:Cognition; D003404:Creatinine / Q000097:blood; D015314:Dialysis Solutions; D056344:Executive Function; D005260:Female; D005500:Follow-Up Studies; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D016030:Kidney Transplantation / Q000523:psychology*; D008137:Longitudinal Studies; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D010758:Phosphorus / Q000097:blood; D011597:Psychomotor Performance; D011930:Reaction Time; D006435:Renal Dialysis / Q000379:methods / Q000523:psychology*; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000523:psychology* / Q000628:therapy*; D013997:Time Factors; D014706:Verbal Learning
chemical_list: D015314:Dialysis Solutions; D006454:Hemoglobins; D010758:Phosphorus; D003404:Creatinine