Increased presence of cognitive impairment in hemodialysis patients in the absence of neurological events.

Background/aims: Cognitive impairment (CI) is highly prevalent among hemodialysis (HD) patients and is associated with increased morbidity and mortality. The aim was to compare cognitive function in HD patients with no history of stroke or dementia and well-matched controls. Studies are required to determine the impact of HD and chronic kidney disease-specific risks on CI.

Methods: 76 outpatients (50 receiving outpatient HD and 26 with normal kidney function matched for age and comorbidity) underwent a cross-sectional observational study. HD patients were well dialyzed and had optimal hemoglobin levels. A battery of eight neuropsychological tests was used. Outcomes included assessment scores of neurocognitive testing and prevalence and subtype of CI.

Results: Compared to controls, HD subjects had significantly lower composite scores for each tested cognitive domain. In each domain except memory, the percentage of subjects with impairment was significantly higher in HD subjects than controls. Differences between the groups were independent of vascular and dementia risk factors. 82% of HD subjects met criteria for CI versus 50% of controls. Non-amnestic subtype of CI was more prevalent in both groups.

Conclusion: Well-dialyzed HD patients with optimized hemoglobin levels and with no history of stroke or dementia performed significantly worse on multiple measures of cognition compared to controls. A higher prevalence of non-memory impairment may suggest an underlying vascular versus neurodegenerative mechanism. HD and chronic kidney disease-specific risk factors may contribute to early CI not readily detected by routine screening methods.