“Is It Removed During Dialysis?”—Cognitive Dysfunction in Advanced Kidney Failure—A Review Article

Abstract

Cognitive impairment is independently associated with kidney disease and increases in prevalence with declining kidney function. At the stage where kidney replacement therapy is required, with dialysis or transplantation, cognitive impairment is up to three times more common, and can present at a younger age. This is not a new phenomenon. The cognitive interactions of kidney disease are long recognized from historical accounts of uremic encephalopathy and so-called “dialysis dementia” to the more recent recognition of cognitive impairment in those undergoing kidney replacement therapy (KRT). The understanding of cognitive impairment as an extra-renal complication of kidney failure and effect of its treatments is a rapidly developing area of renal medicine. Multiple proposed mechanisms contribute to this burden. Advanced vascular aging, significant multi-morbidity, mood disorders, and sleep dysregulation are common in addition to the disease-specific effects of uremic toxins, chronic inflammation, and the effect of dialysis itself. The impact of cognitive impairment on people living with kidney disease is vast ranging from increased hospitalization and mortality to decreased quality of life and altered decision making. Assessment of cognition in patients attending for renal care could have benefits. However, in the context of a busy clinical service, a pragmatic approach to assessing cognitive function is necessary and requires consideration of the purpose of testing and resources available. Limited evidence exists to support treatments to mitigate the degree of cognitive impairment observed, but promising interventions include physical or cognitive exercise, alteration to the dialysis treatment and kidney transplantation. In this review we present the history of cognitive impairment in those with kidney failure, and the current understanding of the mechanisms, effects, and implications of impaired cognition. We provide a practical approach to clinical assessment and discuss evidence-supported treatments and future directions in this ever-expanding area which is pivotal to our patients' quality and quantity of life.

Neuropsychological Assessment of Cognitive Impairment in Kidney Transplantation (NAsKiT) and its related risk factors: a study protocol

“…Other studies have also found similar decline in cognition with the presence of depression [45,47,48]. This can be explained by the effects of symptoms of depression on domains of cognition like executive functioning and processing speed [48,49]. A recent meta-analysis also shows that subjective stress influences the development of cognitive impairment [50].…”

Healthy aging and chronic kidney disease

“…The presence of cognitive impairment in patients with CKD was first described by Dr. Thomas Addison in 1839 and, despite its significant association with poor treatment compliance, decision-making, readmissions, worsening kidney function, falls, and mortality, screening for cognitive impairment is not routinely conducted in the nephrology clinic [39]. More than half of HD patients with cognitive impairment are nonadherent to their medications [40].…”

“…Edmonton Frail Scale [36] Based on the following www.krcp-ksn.org eGFR is associated with an 11% increase in cognitive impairment prevalence amongst those aged >55 years. There is a rapid decline in cognition for those with eGFR of <30 mL/min/1.73 m 2 , where more than three quarters of those undergoing dialysis and up to 2/3 of pre-dialysis patients may have underlying cognitive impairment [32,39]. The initiation of dialysis can cause a stepwise decline in cognition, especially executive function [41].…”

“…Similar to frailty, the choice of test is dependent on its utility, time taken, threshold for intervention, and intended outcome overall. Cognitive tests (Table 2) [39,[45][46][47][48][49][50][51][52] can vary from neuropsychological assessment, which takes >60 minutes in some patients and is costly to perform, to brief methods of triage, such as a single screening question or the Rapid Cognitive Screen or Mini-Cog exam [45]. Multidomain screening methods, such as the Mini-Mental State Examination and the Montreal Cognitive Assessment (which takes up to 15 minutes) are frequently used in clinical practice [39,46,47].…”

Neurological Complications Associated with Hemodialysis

“…Therefore, it is believed that the recurrent intradialytic decline in cerebral blood flow could predispose to cerebral ischemic injuries leading to vascular dementia. 4…”