Cognitive impairment (CI) is extremely common among dialysis patients affecting up to ~70% or more of patients (1-3). Pre-existing conditions, dialysis process itself and uremic, metabolic and vascular disturbances associated with end stage renal failure may all contribute to the CI in patients on dialysis (1-5).
Among pre-existing conditions, vascular disease is considered the major contributing factor to the risk of CI in dialysis patients (3). The prevalence of stroke is very high among hemodialysis (HD) ( ~15%) and CKD patients (~10%) compared to non-CKD patients (~2%). History of stroke also doubles the risk of dementia in both the non-CKD and HD patients. Subclinical cerebrovascular disease due to silent strokes and white matter disease —common in CKD and dialysis patients—are also associated with increased risk of cognitive and physical decline and incident dementia. White matter disease is thought to be related to microvascular disease and chronic hypoperfusion (1).
Dialysis itself may be associated with acute confusional state due to cerebral edema caused by acute fluid, urea, and electrolyte shifts during dialysis (particularly among newly initiated HD patients). Some have suggested that the optimal cognitive function in HD patients is around 24 h after HD (1).
Chronic rapid fluctuations in blood pressure, removal of large fluid volumes and hemoconcentrations can further increase the risk of cerebral hypoperfusion, potentially accelerating vascular cognitive impairment in HD patients (1).
Bonus Pearl: Did you know that while cerebral ischemia (measured by PET-CT or other non-invasive means) is common during HD, it may occur in the absence of intra-dialysis hypotension (6,7)?
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- Murray AM. Cognitive impairment in the aging dialysis and chronic kidney disease populations: an occult burden. Adv Chronic Kidney Dis 2008;15:123-32. https://www.ackdjournal.org/article/S1548-5595(08)00011-6/pdf
- Murray AM, Tupper DE, Knopman DS, et al. Cognitive impairment in hemodialysis patients is common. Neurology 2006;67:216-223. https://experts.umn.edu/en/publications/cognitive-impairment-in-hemodialysis-patients-is-common
- Van Zwieten A, Wong G, Ruospo M, et al. Prevalence and patterns of cognitive impairment in adult hemodialysis patients: the COGNITIVE-HD study. Nephrol Dial Transplant 208;33:1197-1206. https://pubmed.ncbi.nlm.nih.gov/29186522/
- Seliger SL, Weiner DE. Cognitive impairment in dialysis patients: focus on the blood vessels? Am J Kidney Dis 2013;61:187-90. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4433757/
- Findlay MD, Dawaon J, Dickie DA, et al. Investigating the relationship between cerebral blood flow and cognitive function in hemodialysis patients. J Am Soc Nephrol 30:147-58. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317612/
- Polinder-Bos HA, Garcia DV, Kuipers J, et al. Hemodiaysis induces an acute decline in cerebral blood flow in elderly patients. J Am Soc Nephrol 208;29:1317-25. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5875962/
- MacEwen C, Sutherland S, Daly J, et al. Relationship between hypotension and cerebral ischemia during hemodialysis. J Am Soc Nephrol 2017;38:2511-20. https://www.researchgate.net/publication/314298128_Relationship_between_Hypotension_and_Cerebral_Ischemia_during_Hemodialysis
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