The nature of impairments of memory in patients with end-stage renal disease (ESRD)

Association between Cognitive Impairment and Malnutrition in Hemodialysis Patients: Two Sides of the Same Coin

Cognitive impairment and malnutrition are prevalent in patients on hemodialysis (HD), and they negatively affect the outcomes of HD patients. Evidence suggests that cognitive impairment and malnutrition may be associated, but clinical studies to assess this association in HD patients are lacking. The aim of this study was to evaluate the association between cognitive impairment evaluated by the Montreal Cognitive Assessment (MoCA) score and nutritional status evaluated by the malnutrition inflammation score (MIS) in HD patients. We enrolled 84 HD patients (44 males and 40 females; age: 75.8 years (63.5-82.7); HD vintage: 46.0 months (22.1-66.9)). The MISs identified 34 patients (40%) as malnourished; the MoCa scores identified 67 patients (80%) with mild cognitive impairment (MCI). Malnourished patients had a higher prevalence of MCI compared to well-nourished patients (85% vs. 70%; p = 0.014). MoCa score and MIS were negatively correlated (rho:-0.317; p < 0.01). Our data showed a high prevalence of MCI and malnutrition in HD patients. Low MoCA scores characterized patients with high MISs, and malnutrition was a risk factor for MCI. In conclusion, it is plausible that MCI and malnutrition are linked by common sociodemographic, clinical, and biochemical risk factors rather than by a pathophysiological mechanism.

Emotional and cognitive changes in chronic kidney disease

Chronic kidney disease (CKD) leads to cognitive impairment and emotional changes. However, the precise mechanism underlying the crosstalk between the kidneys and the nervous system is not fully understood. Inflammation and cerebrovascular disease can influence the development of depression in CKD. CKD is one of the strongest risk factors for cognitive impairment. Moreover, cognitive impairment occurs in CKD as patients experience the dysregulation of several brain functional domains due to damage caused to multiple cortical regions and to subcortical modulatory neurons. The differences in structural brain changes between CKD and non-CKD dementia may be attributable to the different mechanisms that occur in CKD. The kidney and brain have similar anatomical vascular systems, which may be susceptible to traditional risk factors. Vascular factors are assumed to be involved in the development of cognitive impairment in patients with CKD. Vascular injury induces white matter lesions, silent infarction, and microbleeds. Uremic toxins may also be directly related to cognitive impairment in CKD. Many uremic toxins, such as indoxyl sulfate, are likely to have an impact on the central nervous system. Further studies are required to identify therapeutic targets to prevent changes in the brain in patients with CKD.

Mechanisms of cognitive dysfunction in CKD

Cognitive impairment is an increasingly recognized major cause of chronic disability and is commonly found in patients with chronic kidney disease (CKD). Knowledge of the relationship between kidney dysfunction and impaired cognition may improve our understanding of other forms of cognitive dysfunction. Patients with CKD are at an increased risk (compared with the general population) of both dementia and its prodrome, mild cognitive impairment (MCI), which are characterized by deficits in executive functions, memory and attention. Brain imaging in patients with CKD has revealed damage to white matter in the prefrontal cortex and, in animal models, in the subcortical monoaminergic and cholinergic systems, accompanied by widespread macrovascular and microvascular damage. Unfortunately, current interventions that target cardiovascular risk factors (such as anti-hypertensive drugs, anti-platelet agents and statins) seem to have little or no effect on CKD-associated MCI, suggesting that the accumulation of uraemic neurotoxins may be more important than disturbed haemodynamic factors or lipid metabolism in MCI pathogenesis. Experimental models show that the brain monoaminergic system is susceptible to uraemic neurotoxins and that this system is responsible for the altered sleep pattern commonly observed in patients with CKD. Neural progenitor cells and the glymphatic system, which are important in Alzheimer disease pathogenesis, may also be involved in CKD-associated MCI. More detailed study of CKD-associated MCI is needed to fully understand its clinical relevance, underlying pathophysiology, possible means of early diagnosis and prevention, and whether there may be novel approaches and potential therapies with wider application to this and other forms of cognitive decline.

A potential barrier to adherence? Memory for future intentions is impaired in hemodialysis patients

INTRODUCTION

End-stage renal disease (ESRD) has been associated with a range of cognitive deficits, including impaired retrospective memory and attention. Prospective memory (PM) is memory for future intentions, such as remembering to take medication on time. Prospective memory has not been examined in any ESRD patients; yet, the implications upon diet and medication management could potentially have detrimental effects on patient welfare. This is the first study to examine PM in ESRD patients being treated with hemodialysis (HD).

METHODS

Hemodialysis patients (n = 18) were compared with age-matched and education-matched controls (n = 18) on a boardgame task that emulates a typical week of activities (i.e., grocery shopping, meetings with friends), requiring the participant to remember a series of upcoming tasks. Other measures were also examined, including general cognitive decline, measures of independent living, IQ, and mood.

FINDINGS

Patients recalled significantly fewer upcoming events than the control group, suggesting an impairment of PM. No significant relationship was found between PM performance and any other measures, suggesting the difference between groups is likely due to the effects of ESRD, HD treatment, or some associated comorbidity.

DISCUSSION

This is the first study to demonstrate a PM deficit in patients undergoing HD treatment. This finding contributes to the current knowledge of the cognitive profile of patients undergoing HD while also highlighting the implications that a PM deficit may have on patient quality of life. The finding may go some way to explaining variances in patients' ability to monitor and adhere to medication and dietary regimes and, ultimately, to live independently. The study also highlights the necessity of viewing treatment for ESRD as a holistic process to maximize patient well-being.

Understanding the impact of haemodialysis on UK National Health Service patients' well-being: A qualitative investigation

Aims and objectives

While haemodialysis is an effective treatment for end‐stage renal disease, the requirements and restrictions it imposes on patients can be onerous. The aim of this study was to obtain UK National Health Service patients’ perspectives on the challenges arising from haemodialysis with the intention of identifying potential improvements.

Background

Depression rates are particularly high in those with end‐stage renal disease; however, there is limited insight into the range of stressors associated with haemodialysis treatment within the National Health Service contributing to such high rates, particularly those of a cognitive or psychological nature.

Design

A qualitative approach was used to obtain rich, patient‐focused data; one‐to‐one semi‐structured interviews were conducted with twenty end‐stage renal disease at a UK National Health Service centre.

Methods

Patients were interviewed during a typical haemodialysis session. Thematic analysis was used to systematically interpret the data. Codes were created in an inductive and cyclical process using a constant comparative approach.

Results

Three themes emerged from the data: (i) fluctuations in cognitive/physical well‐being across the haemodialysis cycle, (ii) restrictions arising from the haemodialysis treatment schedule, (iii) emotional impact of haemodialysis on the self and others. The findings are limited to predominantly white, older patients (median = 74 years) within a National Health Service setting.

Conclusions

Several of the experiences reported by patients as challenging and distressing have so far been overlooked in the literature. A holistic‐based approach to treatment, acknowledging all aspects of a patient's well‐being, is essential if optimal quality of life is to be achieved by healthcare providers.

Relevance to clinical practice

The findings can be used to inform future interventions and guidelines aimed at improving patients’ treatment adherence and outcomes, for example, improved reliable access to mental health specialists.

Stereopsis in end-stage renal disease (ESRD)

We investigated an effect of end-stage renal disease (ESRD) on the visual system by measuring the ability of 21 patients to perceive depth in the random dot stereograms and circles of the Randot Test. To control for other factors which might influence performance on the tests of stereopsis, patients were compared with healthy controls matched for age, years of education, IQ, and general cognitive ability. Vernier acuity (thought to reflect mainly central processing) and Landolt acuity (more sensitive to retinal and optical abnormalities) were also measured, but the study did not include a formal ophthalmological examination. All controls could perceive depth in random dot stereograms, whereas 9/21 patients could not. Patients who could perceive depth had worse stereoacuity than did their matched controls. The patient group as a whole had worse Vernier and Landolt acuities than the controls. The stereoblind patient subgroup had similar Vernier acuity to the stereoscopic subgroup, but worse Landolt acuity, and was more likely to have peripheral vascular disease. We conclude that ESRD had affected structures both within the eye, and within the visual brain. However, the similarity of Vernier acuity and difference of Landolt acuity in the stereoblind and stereoscopic patient subgroups suggest that the differences in stereoscopic ability arise from abnormalities in the eyes rather than in the brain.