Cognitive Function Declines Significantly during Haemodialysis in a Majority of Patients: A Call for Further Research

Mid- and Late-Life Chronic Kidney Disease Is Associated with Parkinson's Disease, Not with an Increased Risk of Alzheimer's Disease

Chronic kidney disease (CKD) is strongly associated with dementia. However, its independent association with Alzheimer's or Parkinson's disease remains unclear. This study investigated the prospective association of patients with CKD aged ≥55 years with an increased risk of Alzheimer's or Parkinson's disease. We conducted a retrospective cohort analysis using a national cohort sample of approximately one million patients. Primary outcome indicators measured included incidence of all-cause dementia, Alzheimer's disease, and Parkinson's disease events using person-years at risk. The hazard ratio was adjusted using the Cox proportional hazards model. We included 952 patients without CKD and 476 with CKD over 55 years using propensity score matching. The CKD group exhibited higher incidences of all-cause dementia, Parkinson's disease, and Alzheimer's disease than the non-CKD group. Furthermore, the CKD group had an elevated risk of all-cause dementia and a significantly increased risk of Parkinson's disease, especially among older women. Notably, the risk of Parkinson's disease was higher within the first 3 years of CKD diagnosis. These findings emphasize the link between CKD in mid- and late-life individuals and a higher incidence of all-cause dementia and Parkinson's disease rather than Alzheimer's disease.

Prediction model for cognitive impairment in maintenance hemodialysis patients

PURPOSE

To explore the risk factors for cognitive impairment in patients undergoing maintenance hemodialysis (MHD) and construct a predictive model for cognitive impairment.

METHODS

A total of 146 patients with end-stage renal disease (ESRD) undergoing MHD were recruited at our hospital between December 2021 and April 2022. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA), and scores of < 26 were considered indicative of cognitive impairment. Risk factors were identified using a multivariate logistic regression model, and a receiver operating characteristic curve was applied to construct the prediction model. Cognitive impairment risk was categorized using a multifactorial prediction model based on the weight of evidence.

RESULTS

46 patients with cognitive impairment were identified, with a prevalence of 31.5% in ESRD patients undergoing MHD. Multivariate logistic regression analyses indicated that the following factors were associated with an increased risk of cognitive impairment in patients undergoing MHD: aged 55.0-64.0 years (OR:6.24; 95%CI:1.81-21.48; P = 0.001), aged 65.0-74.0 years (OR:16.10; 95%CI:4.03-64.37; P < 0.001), aged ≥ 75.0 years (OR:90.22; 95%CI:16.86-482.86; P < 0.001), duration of dialysis ≥ 5 years (OR:3.99; 95%CI:1.58-10.04; P = 0.003), and current smoker (OR:4.61; 95%CI:1.46-14.57; P = 0.009). The predictive value of the constructed model based on the aforementioned factors for cognitive impairment was 84% (95%CI,77-91%). The prevalence of cognitive impairment for patients at low, moderately low, moderately high, and high risk was 0% (95%CI:0-17%), 10% (95%CI:3-22%), 32% (95%CI:16-52%), and 65% (95%CI:50-78%), respectively.

CONCLUSIONS

This study constructed a multifactorial prediction model with a high predictive value for cognitive impairment in patients with ESRD undergoing MHD.

Relationship between Lower Extremity Peripheral Arterial Disease and Mild Cognitive Impairment in Hemodialysis Patients

Background: The link between arterial stiffness and mild cognitive impairment (MCI) in patients on hemodialysis (HD) has been receiving increased attention. The purpose of this study was to investigate the relationship between cognitive function and ankle brachial index (ABI) and toe brachial index (TBI) values in patients on hemodialysis. Of the 100 participants (mean age: 67.9 years; average history of hemodialysis: 7.3 years). Of these, 46.0% had MCI. The MoCA-J scores were significantly higher in the ABI ≥ 1.06 group. However, the MoCA-J scores divided into the two groups according to the TBI cutoff value were not significantly different. In a multiple regression model with the MoCA-J scores as the objective variable, the ABI was a significantly associated factor. This study indicates that a low ABI might be associated with MCI.

Relations of hippocampal subfields atrophy patterns with memory and biochemical changes in end stage renal disease

End-stage renal disease (ESRD) results in hippocampal volume reduction, but the hippocampal subfields atrophy patterns cannot be identified. We explored the volumes and asymmetry of the hippocampal subfields and their relationships with memory function and biochemical changes. Hippocampal global and subfields volumes were derived from 33 ESRD patients and 46 healthy controls (HCs) from structural MRI. We compared the volume and asymmetric index of each subfield, with receiver operating characteristic curve analysis to evaluate the differentiation between ESRD and HCs. The relations of hippocampal subfield volumes with memory performance and biochemical data were investigated in ESRD group. ESRD patients had smaller hippocampal subfield volumes, mainly in the left CA1 body, left fimbria, right molecular layer head, right molecular layer body and right HATA. The right molecular layer body exhibited the highest accuracy for differentiating ESRD from HCs, with a sensitivity of 80.43% and specificity of 72.73%. Worse learning process (r = 0.414, p = 0.032), immediate recall (r = 0.396, p = 0.041) and delayed recall (r = 0.482, p = 0.011) was associated with left fimbria atrophy. The left fimbria volume was positively correlated with Hb (r = 0.388, p = 0.05); the left CA1 body volume was negatively correlated with Urea (r = - 0.469, p = 0.016). ESRD patients showed global and hippocampal subfields atrophy. Left fimbria atrophy was related to memory function. Anemia and Urea level may be associated with the atrophy of left fimbria and CA1 body, respectively.

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

BACKGROUND

Association of cognitive impairment with chronic kidney disease has been reported over the last decade. Individuals show better cognitive performance after kidney transplantation than individuals on dialysis but are more likely to be affected by cognitive impairment than age-matched comparison groups. Better knowledge of the prevalence as well as course and profile of cognitive impairment is important for the design of future studies assessing the clinical impact of cognitive impairment and developing management strategies. The goal of our study is to examine the extent of cognitive impairment before and after transplantation and to derive a distinct profile of cognitive function using standard neurocognitive tests. Furthermore, we aim to assess whether transplantation per se leads to an improvement in cognitive performance.

METHODS

We are conducting a prospective single-center cohort study involving 100 kidney transplant individuals. Individuals who are wait-listed to receive a kidney transplantation or have already received one will be included in this study. Individuals will undergo a battery of detailed neurocognitive tests at baseline (in part before surgery), and then 3 and 12 months afterwards. Furthermore, the enrolled patients will complete a validated German version of the Cognitive Failure Questionnaire for self-assessment (s-CFQ) as well as the Hospital Anxiety and Depression Scale -Deutsche (HADS-D), a self-report screening instrument with two scales that capture anxiety and depression. In addition, a hair sample will be taken at each measurement time point for the determination of hair cortisol levels as a parameter for the cumulative hypothalamic-pituitary-adrenocortical axis activity over the previous three months. The primary outcome measure will be (a) the effect of kidney transplantation on the cognitive performance up to 12 months after transplantation and (b) the course of cognitive performance following kidney transplantation over time.

DISCUSSION

The results of our study have potentially important implications for the prevention and treatment of cognitive impairment in kidney transplant individuals. By increasing our knowledge of the neurocognitive profile and assigning the corresponding deficits, it might be possible to create an individualized training program to positively impact cognitive deficits in kidney transplant patients.

Experiences of a cognitive behavioural therapy (CBT) intervention for fatigue in patients receiving haemodialysis

BACKGROUND

A feasibility randomised-controlled trial found that a cognitive-behavioural therapy intervention for renal fatigue has the potential to reduce fatigue in patients receiving haemodialysis, but uptake was low.

OBJECTIVES

Nested in the randomised-controlled trial (RC) qualitative interviews were undertaken to understand the acceptability of renal fatigue, the facilitators of, and barriers to, engagement, and the psychosocial processes of change.

DESIGN

The trial included 24 participants at baseline. Semi-structured interviews were conducted with nine participants from the intervention arm (n = 12). Approach Interviews were carried out immediately following treatment (3 months post-randomisation). Data were analysed using inductive thematic analysis.

FINDINGS

Five main themes were formulated. The overarching theme was a sense of coherence (whether the illness, symptoms and treatment made sense to individuals), which appeared to be central to acceptability and engagement. Two themes captured the key barriers and facilitators to engagement, cognitive and illness/treatment burdens and collaboration with the therapist. Participants described changes related to their activity, thoughts and social identity/interactions, which shaped perceptions of change in fatigue. Lastly, participants discussed the optimal delivery of the intervention.

CONCLUSIONS

This study revealed the importance of patients' understanding of fatigue and acceptance of the treatment model for the acceptability of and engagement with a cognitive-behavioural therapy-based intervention for fatigue. Overall, there was an indication that such an intervention is acceptable to patients and the mechanisms of change align with the proposed biopsychosocial model of fatigue. However, it needs to be delivered in a way that is appealing and practical to patients, acknowledging the illness and treatment burdens.

Assessment of cognitive impairment and related risk factors in hemodialysis patients

Background

Cognitive impairment in hemodialysis patients has been acknowledged over the last years and has been reported in up to 80% of patients. Older age, high prevalence of cardiovascular risk factors, such as stroke and transient ischemic attack, uremia, and multiple metabolic disturbances represent the most common factors for cognitive impairment in hemodialysis patients.

Methods

We conducted a prospective cohort study on 408 patients from 10 hemodialysis centers in the regional government district of Middle Hesse (Germany). Patients underwent a neuropsychological test battery consisting of five tests, in addition to a phonemic fluency test, to assess cognitive profile. The patients were classified as no cognitive impairment or mildly-, moderately- or severely-impaired cognitive function, depending on the degree of impairment and number of domains where the deficit was determined. We analyzed the cognitive profile and the change in performance over time in hemodialysis patients based on their cognitive status at baseline vs. 1-year follow-up.

Results

Of 479 eligible patients, 408 completed all tests at baseline. Only 25% (n = 102) of the patients had no cognitive impairment. Fourteen per cent (n = 57), 36.5% (n = 149), and 24.5% (n = 100) of patients showed mild, moderate, and severe impairment, respectively. In patients with cognitive impairment, all cognitive domains were affected, and impairment was significantly associated with depression and education. The most impaired cognitive performance was immediate memory recall, and the best performance was found in naming ability. No significant  change was observed after 1-year follow up in any domain.

Conclusion

Our study shows that the prevalence of cognitive impairment in hemodialysis patients is high and that it is affected by the presence of depression. Furthermore, education has an effect on cognitive test results. As depression has a significant influence on cognitive impairment, its early identification is essential in order to initiate treatment at an early stage, hoping to positively influence cognitive performance.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40620-021-01170-3.

Factors that contribute to the cognitive impairment in elderly dialysis patients

AIM

To evaluate the cognitive function in dialysis patients over 60 years old and identify the contributing factors.

METHODS

A group of elderly dialysis patients in the Department of Nephrology, Pan'an People's Hospital between March 2015 and June 2018 were chosen as the subjects for this study. Patients were divided into two groups, those with cognitive impairment and those with normal cognitive function. Results of their Montreal Cognitive Assessment (MoCA) scores, Controlled Oral Word Association Test (COWAT), Wechsler Adult Intelligence Scale Digit Span subtest (WDMS), and Stanford Diagnostic Math Test (SDMT) were reviewed and analyzed.

RESULTS

Among the 110 elderly dialysis patients, 75 patients (68.18%) showed different levels of damage to their cognitive function. Their assessment scores on MoCA (total), MoCA subtests: visuospatial/executive, naming, attention, language, delayed recall, abstraction and orientation, COWAT (total), COWAT1, COWAT2, COWAT3, WMDS-Backward, and SDMT are significantly lower than patients with normal cognitive abilities (p < 0.05). Further analysis showed that the highest percentage (72.00%) of patients had impairment with visuospatial/executive function; and, of the 75 cognitive impaired patients, 37.33% showed cognitive damage in two MoCA subtests simultaneously. Patients with and without cognitive impairment showed a significant (p < 0.05) difference on factors including age, education level, employment status, financial situation, dialysis vintage, serum albumin, and hemoglobin.

CONCLUSION

Elderly patients on dialysis have a higher risk of becoming cognitive impaired. The cognitive impairment in elderly dialysis patients was significantly associated with age, dialysis vintage, and levels of serum albumin and hemoglobin.

Cognitive performance in dialysis patients - "when is the right time to test?"

Background

Cognitive impairment in chronic kidney disease, especially in end stage renal disease, is a public health problem. Nevertheless, the cause of chronic kidney disease still remains unclear. A prevalence of cognitive impairment in patients with end stage renal disease of up to 87% has been found.

Methods

The study at hand deals with the research on the – potential – effect of timing on cognitive performance when testing cognitive impairment in hemodialysis patients during the dialysis cycle. We tested cognitive performance with a neuropsychological test battery (RBANS, Repeatable Battery for the Assessment of Neuropsychological Status) on two occasions while patients were on dialysis as well as on a dialysis-free day. In addition, all participants were rated using the Geriatric Depression Scale (GDS) and several demographic and clinical variables were recorded in order to investigate their possible influence on cognitive performance.

The patients were recruited in three dialysis centers in the central region of Hesse, Germany. Twenty-six participants completed the 3 testings during a period of 6 weeks. The testing was carried out in the dialysis centers.

Results

Looking at the total scale score, patients achieved the best cognitive performance in the RBANS during the first 2 h on dialysis with 81.1 points. When comparing the scores of the three measurement occasions (first 2 h, Timepoint 1 vs. last 2 h, Timepoint 2 vs. dialysis free day, Timepoint 3, however, no significant difference in the total scale score was detected. But patients showed significantly better cognitive performance in language in the first 2 h (p < 0.001) as well as in the last 2 h (p < 0.001) compared with the dialysis-free day.

Conclusion

Due to the high prevalence of cognitive impairment, there is an increasing need to assess cognitive function in dialysis patients. Our data show that the time point of testing (first 2 h on hemodialysis vs. last 2 h on hemodialysis vs. Hemodialysis free day) had no influence of cognitive function in hemodialysis patients in routine indications.

Reduced regional cerebral venous oxygen saturation is a risk factor for the cognitive impairment in hemodialysis patients: a quantitative susceptibility mapping study

The purpose of this study was to noninvasively evaluate the changes of regional cerebral venous oxygen saturation (rSvO₂) in hemodialysis patients using quantitative susceptibility mapping (QSM) and investigate the relationship with clinical risk factors and neuropsychological testing. Fifty four (54) hemodialysis patients and 54 age, gender and education matched healthy controls (HCs) were recruited in this prospective study. QSM data were reconstructed from the original phase data of susceptibility weighted imaging to measure the susceptibility of cerebral regional major veins in all subjects and calculate their rSvO₂. The differences in rSvO₂ between hemodialysis patients and HCs were investigated using analysis of covariance adjusting for age and gender as covariates. Stepwise multiple regression and correlation analysis were performed between the cerebral rSvO₂ and clinical factors including neuropsychological testing. The SvO₂ of the bilateral cortical, thalamostriate, septal, cerebral internal and basal veins in hemodialysis patients was significantly lower than that in HCs (p < 0.001, Bonferroni corrected). The cerebral rSvO₂ in all these veins was reduced by 1.67% to 2.30%. The hematocrit, iron, glucose, pre-and post-dialysis diastolic blood pressure (DBP) were independent predictive factors for the cerebral rSvO₂ (all P < 0.05). The Mini-Mental State Examination and Montreal Cognitive Assessment (MoCA) scores were both lower in patients than those in HCs (both P < 0.05). The SvO₂ of the left cerebral internal vein correlated with MoCA scores (r = 0.492; P = 0.02, FDR corrected). In conclusion, our study indicated that the cerebral rSvO₂ was reduced in hemodialysis patients, which was the risk factor for neurocognitive impairment. The hematocrit, iron, glucose, pre-and post-dialysis DBP were independent risk factors for the cerebral rSvO₂.

Intradialytic hypotension and relationship with cognitive function and brain morphometry

Background

The haemodynamic stress brought about by dialysis could justify the loss of structural and functional integrity of the central nervous system (CNS). The main objective of this study was to analyse the relationship between intradialytic hypotension (IDH) and cognitive function and brain morphometry.

Methods

The cross-sectional KIDBRAIN study (Cohort Study of Morphological Changes of the Brain by MRI in Chronic Kidney Disease Patients) included 68 prevalent patients with no history of neurological disorders (cerebrovascular disease and cognitive impairment) undergoing haemodialysis (HD). We analysed 18 non-consecutive dialysis sessions (first three of each month over a 6-month period) and various definitions of IDH were recorded. Global cognitive function (GCF) was assessed using the Mini-Mental State Examination (MMSE) and parameters of structural integrity of the CNS were obtained using volume morphometry magnetic resonance imaging analysis [grey matter (GM), white matter (WM) and hippocampus).

Results

A greater number of sessions with IDH were associated with less volume of WM (r = −0.359,P = 0.003) and hippocampus (r = −0.395, P = 0.001) independent of cardiovascular risk factors according to multivariable linear regression models (β = −0.198, P = 0.046 for WM; β = −0.253, P = 0.017 for hippocampus). The GCF by the MMSE was 27.3 ± 7.3.1 and was associated with WM volume (β = 0.403, P = 0.001) independent of GM and hippocampus volume. Symptomatic IDH was associated with GCF (r = −0.420, P < 0.001) in adjusted analysis (β = −0.339, P = 0.008).

Conclusions

Even when asymptomatic, IDH is associated with a lower WM and hippocampus volume and reduced GCF in patients undergoing HD, thus suggesting greater vulnerability of the brain to the haemodynamic stress that may be generated by a dialysis session.

Evaluation of the effect of Cooled HaEmodialysis on Cognitive function in patients suffering with end-stage KidnEy Disease (E-CHECKED): feasibility randomised control trial protocol

BACKGROUND

Cognitive impairment is common in haemodialysis (HD) patients and is associated independently with depression and mortality. This association is poorly understood, and no intervention is proven to slow cognitive decline. There is evidence that cooler dialysis fluid (dialysate) may slow white matter changes in the brain, but no study has investigated the effect of cooler dialysate on cognition. This study addresses whether cooler dialysate can prevent the decline in cognition and improve quality of life (QOL) in HD patients.

METHODS

This is a multi-site prospective randomised, double-blinded feasibility trial.

SETTING

Four HD units in the UK.

PARTICIPANTS AND INTERVENTIONS

Ninety HD patients randomised (1:1) to standard care (dialysate temperature 36.5 °C) or intervention (dialysate temperature 35 °C) for 12 months.

PRIMARY OUTCOME MEASURE

Change in cognition using the Montreal Cognitive Assessment (MoCA).

SECONDARY OUTCOME MEASURES

Recruitment and attrition rates, reasons for non-recruitment, frequency of intradialytic hypotension, depressive symptom scores, patient and carers burden, a detailed computerised cognitive test and QOL assessments.

ANALYSIS

mixed method approach, utilising measurement of cognition, questionnaires, physiological measurements and semi-structured interviews.

DISCUSSION

The results of this feasibility trial will inform the design of a future adequately powered substantive trial investigating the effect of dialysate cooling on prevention and/or slowing in cognitive decline in patients undergoing haemodialysis using a computerised battery of neuro-cognitive tests. The main hypothesis that would be tested in this future trial is that patients treated with regular conventional haemodialysis will have a lesser decline in cognitive function and a better quality of life over 1 year by using cooler dialysis fluid at 35 °C, versus a standard dialysis fluid temperature of 36.5 °C. This also should reflect in improvements in their abilities for activities of daily living and therefore reduce carers' burden. If successful, the treatment could be universally applied at no extra cost.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03645733 . Registered retrospectively on 24 August 2018.

The Burden of Frailty on Mood, Cognition, Quality of Life, and Level of Independence in Patients on Hemodialysis: Regina Hemodialysis Frailty Study

Background:

The prevalence of frailty is disproportionately increased in patients with chronic kidney disease (CKD) in comparison with non-CKD counterparts and is the highest in patients on hemodialysis (HD). While the cross-sectional measurement of frailty on HD has been associated with adverse clinical events, there is a paucity of data on longitudinal assessment of frailty and its relationship to outcomes.

Objective:

The objectives were to (1) evaluate changes in frailty status, level of independence, mood, cognition, and quality of life (QoL) over a 12-month period and (2) explore the relationship between frailty status and level of independence, mood, cognition, and QoL at 2 different time points (at baseline and at 1 year).

Design:

This is a prospective cohort study involving 100 prevalent HD patients.

Setting:

Regina General Hospital and Wascana Dialysis Unit in Regina, Saskatchewan, Canada, between January 2015 and January 2017.

Patients:

One hundred prevalent HD patients underwent frailty assessments using the Fried criteria at baseline and 1 year later.

Measurements:

Frailty was assessed using the Fried criteria, which included assessments of unintentional weight loss, weakness (handgrip strength), slowness (walking speed), and questionnaires for physical activity and self-perceived exhaustion. Cognition, mood, and QoL were measured using questionnaires (Montreal Cognitive Assessment [MoCA], Geriatric Depression Scale [GDS], and EuroQol [EQ-5D] utility scores and visual analog scale [VAS], respectively).

Methods:

Frailty status was reported as a binary variable: frail vs. nonfrail (prefrail and robust). Differences across baseline and 1-year groups were assessed using McNemar’s test or Wilcoxon signed-rank test, as appropriate. We assessed the differences between frail and nonfrail groups using the Mann–Whitney U test or chi-square test/Fisher’s exact test where appropriate.

Results:

Ninety-seven of the 100 patients had complete initial assessments. The median (interquartile range [IQR]) duration of dialysis at baseline was 35.5 (13.75-71.75 months). One year later, 22 had died, 10 refused assessments, and 3 had relocated. In comparison with baseline vs 1 year, the number of frail patients was 68.1% vs. 67.7%; prefrail 26.8% vs. 26.1%; robust 5.1% vs. 6.2%; MoCA ≥24, 69% vs. 64.5%; GDS score ≥ 2, 52.8% vs. 47.7%; median EQ-5D utility score 0.81 vs. 0.77; and median EQ-VAS 60 vs. 50. Similarly, in comparison with baseline vs. 1 year, the number of independent patients was 82% vs. 63%, independent with support 17% vs. 31%, and long-term care home 0% vs. 3.1%. Eighteen of the 22 patients (82%) who died were frail. At 1 year, the median (IQR) MoCA was 24 (19-25) vs. 25 (21-26; P = .039) and median (IQR) GDS was 2 (1-3) vs. 1(0-2; P = .034). Likewise, median (IQR) EQ-5D utility score was 0.78 (0.6-0.82) vs. 0.81 (0.78-0.85; P = .023). There were significant changes in self-care (27% vs. 0%), P = 0.006, and daily activities (68.2% vs. 38.1%), P = 0.021.

Limitations:

This is a single-center study, so direct inferences must be interpreted in the context of the demographics of the study population. Patients were undergoing dialysis for a median of 36 months before undergoing initial assessment.

Conclusions:

Frailty and prefrailty in our dialysis patients is near-ubiquitous and will need to be proactively addressed to improve subsequent health care outcomes.