Cognitive dysfunction is reportedly highly prevalent among chronic kidney disease (CKD) patients. A variety of screening tools and neuropsychiatric batteries are used to quantify the magnitude and nature of this dysfunction. Our objective is to summarize the neurocognitive testing used, and determine what degree cognitive dysfunction is reported in CKD patients. All study designs published in English that contained participants who were either pre‐dialysis patients, haemodialysis (HD) or peritoneal dialysis (PD) patients or renal transplant recipients were considered. Reported comparative non‐CKD control data was also collected. All study designs were included. The search period encompassed articles from 1980 to May 2018. This review is registered with PROSPERO (CRD42018096568). Of the 1711 articles screened, 148 articles were relevant and used in the meta‐analysis. Commonly used assessments were The Mini–Mental State Examination (MMSE), The Modified Mini–Mental State Examination, the Trails Making Tests (TMT) forms A and B and components of the Wechsler Adult Intelligence Scale: Digit Span and Digit Symbol. Means for all assessments were adjusted using a random effects model to account for the differences in variance. Adjusted mean MMSE scores were significantly lower for both pre‐dialysis (26.08, n = 17 073) and HD (26.31, n = 3314) patients when compared to non‐CKD controls (28.21, n = 5226). PD (58.01 s, n = 859) and HD (56.04 s, n = 2344) patients also took significantly longer to complete the Trails Making Task A than non‐CKD controls (37.62 s, n = 4809). Patients with CKD, especially pre‐dialysis and those requiring dialysis, are likely to exhibit impairments in cognition that can be identified with specific screening neuropsychological assessments.

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Background Acute kidney injury (AKI) is associated with long-term morbidity and mortality. The effects of AKI on neurocognitive functioning remain unknown. Our objective was to quantify neurocognitive impairment after an episode of AKI. Methods Survivors of AKI were compared with age-matched controls, as well as a convenience sample of patients matched for cardiovascular risk factors with normal kidney function (active control group). Patients with AKI completed two assessments, while the active control group completed one assessment. The assessment included a standardized test: the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and a robotic assessment: Kinarm. Results The cohort consisted of 21 patients with AKI, 16 of whom completed both assessments, and 21 active control patients. The majority of patients with AKI had Kidney Disease: Improving Global Outcomes Stage 3 AKI (86%), 57% received dialysis and 43% recovered to ≤25% of their baseline serum creatinine by their first assessment. Compared with the RBANS, which detected little impairment, the Kinarm categorized patients as impaired in visuomotor (10/21, 48%), attention (10/20, 50%) and executive tasks (11/21, 52%) compared with healthy controls. Additionally, patients with AKI performed significantly worse in attention and visuomotor domains when compared with the active controls. Neurocognitive performance was generally not impacted by the need for dialysis or whether kidney function recovered. Conclusions Robotic technology identified quantifiable neurocognitive impairment in survivors of AKI. Deficits were noted particularly in attention, visuomotor and executive domains. Further investigation into the downstream health consequences of these neurocognitive impairments is warranted.

Background: Neurocognitive impairment is a common finding across the spectrum of kidney disease and carries important consequences for quality of life. We previously demonstrated that robotic technology can identify neurocognitive impairments not readily detectable by traditional testing in patients with acute kidney injury (AKI) and chronic kidney disease (CKD). Objective: The present study aimed to assess whether these quantifiable deficits in neurocognition differ based on a diagnosis of AKI, CKD, or kidney failure. Design: This was a cross-sectional analysis of participants previously enrolled in an observational study. Setting: Patients were enrolled at a tertiary academic hospital, Kingston Health Sciences Centre, Kingston, ON, Canada. Patients: Adults with AKI, CKD, or kidney failure. Measurements: Each participant underwent robotic neurocognitive assessment using the Kinarm: an interactive robotic device that uses a series of behavioral tasks involving movement of the upper limbs to precisely quantify neurocognitive impairment across a variety of neurocognitive domains. Methods: Multilevel modeling was used to determine the effect of Kinarm task type, kidney diagnostic group (AKI vs CKD vs kidney failure), and the interaction between the two, on neurocognitive performance. Results: A total of 104 participants within 1 year of an AKI event or with CKD category G3-5 were enrolled. We found that across all of the kidney diagnostic groups, participants performed worst on the Kinarm tasks of Reverse Visually Guided Reaching ( b = 0.64 [95% confidence interval = 0.42, 0.85]), Visually Guided Reaching ( b = 0.28 [0.07, 0.49]), and Trail Making ( b = 0.50 [0.28, 0.72]), relative to all other tasks. There were no significant differences in average performance across tasks based on kidney diagnostic group. However, diagnostic group and neurocognitive task type interacted to determine performance, such that patients with AKI performed worse than those with either CKD or kidney failure on the Reverse Visually Guided Reaching task. Limitations: Kinarm assessment was performed at a single time point, and the sample size itself was small, which may lead to the risk of a false-positive association despite the use of multilevel modeling. Our sample size also did not permit inclusion of the underlying etiology of kidney impairment as a covariate in our analyses, which may have also influenced neurocognitive function. Conclusions: In this study that utilized the Kinarm to assess neurocognitive function, patients with AKI demonstrated significantly worse neurocognitive functioning than patients with CKD or kidney failure on a task measuring executive function and visuomotor control.

Background: Patients on hemodialysis (HD) are known to exhibit low values of regional cerebral oxygenation (rSO2) and impaired cognitive functioning. The etiology of both is currently unknown. Objective: To determine the feasibility of serially monitoring rSO2 in patients initiating HD. In addition, we sought to investigate how rSO2 is related to hemodynamic and dialysis parameters. Design: Prospective observational study. Setting: Single-center tertiary academic teaching hospital in Ontario, Canada. Participants: Six patients initiating HD were enrolled in the study. Methods: Feasibility was defined as successful study enrollment (>1 patient/month), successful consent rate (>70%), high data capture rates (>90%), and assessment tolerability. Regional cerebral oxygenation monitoring was performed 1 time/wk for the first year of dialysis. A neuropsychological battery was performed 3 times during the study: before dialysis initiation, 3 months, and 1 year after dialysis initiation. The neuropsychological battery included a traditional screening tool: the Repeatable Battery for the Assessment of Neuropsychological Status, and a robot-based assessment: Kinarm. Results: Our overall consent rate was 33%, and our enrollment rate was 0.4 patients/mo. In total 243 rSO2 sessions were recorded, with a data capture rate of 91.4% (222/243) across the 6 patients. Throughout the study, no adverse interactions were reported. Correlations between rSO2 with hemodynamic and dialysis parameters showed individual patient variability. However, at the individual level, all patients demonstrated positive correlations between mean arterial pressure and rSO2. Patients who had more than 3 liters of fluid showed significant negative correlations with rSO2. Less cognitive impairment was detected after initiating dialysis. Limitation: This small cohort limits conclusions that can be made between rSO2 and hemodynamic and dialysis parameters. Conclusions: Prospectively monitoring rSO2 in patients was unfeasible in a single dialysis unit, due to low consent and enrollment rates. However, rSO2 monitoring may provide unique insights into the effects of HD on cerebral oxygenation that should be further investigated. Trial Registration: Due to the feasibility nature of this study, no trial registration was performed.