Subclinical vascular disease of the brain in dialysis patients

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.

Gait disorders in CKD patients: muscle wasting or cognitive impairment? A cross-sectional pilot study to investigate gait signatures in Stage 1-5 CKD patients

BACKGROUND

Instrumental gait analysis in nephrology is widely neglected, although patients with chronic kidney disease (CKD) show brain changes due to cerebrovascular disease and metabolic disorders that can potentially influence gait quality. Our study assesses the association between CKD stages and gait parameters, to understand the prevalent status of brain related gait parameters (i.e. variability) and of performance related parameters (i.e. gait speed, stride length). We hypothesize that gait changes are detectable already in early stages of CKD.

METHODS

Forty-five participants distributed in 5 CKD severity groups underwent an instrumental gait analysis via a triaxial accelerometer affixed to the lower trunk under single- and dual-task conditions. In addition to spatio-temporal parameters, variability and dual-task cost of gait were extracted. A battery of clinical assessments was conducted with the aim of helping to better explain the findings of the gait analysis. A correlation analysis was made to investigate a linear relation between gait parameters and CKD severity.

RESULTS

Statistically significant correlations (Pearson correlation coefficient) with CKD severity were found for gait speed (p < 0.01, r = -0.55, 95% CI [-0.73;-0.30]), stride length ( p < 0.01, r = -0.40, 95% CI [-0.62;-0.12]), step length (p < 0.01, r = -0.41, 95% CI [-0.63;-0.13], coefficient of variance (CV) of step length (p = 0.01, r = 0.36, 95% CI [0.08;0.59]), gait regularity (p < 0.01, r = -0.38, 95% CI [-0.61;-0.10]), dual-task cost of gait speed (p < 0.01, r = 0.40, 95% CI [0.13;0.62]) and dual-task cost of stride time (p = 0.03, r = 0.32, 95% CI [0.03;0.57]). Adjustment for age and gender confirmed all results except for gait regularity. With increasing severity of renal failure, Handgrip strength, Time for the Expanded Timed Get Up and Go test, executive functions, haemoglobin, and haematocrit, worsen.

CONCLUSIONS

The correlation of CKD severity with spatio-temporal parameters (performance indices mainly relatable to peripheral functionality) and with variability of gait (related to central factors) supported by the results of the clinical assessments, suggests that gait disturbance in CKD patients is not only due to metabolic factors that lead to muscle wasting, but also to brain changes that affect motor control. This suggests that the treatment of renal disease should include cognitive aspects in addition to metabolic and functional factors.

Neuropathy - Exponent of Accelerated Involution in Uremia: The Role of Carbamylation

Premature loss of functional integrity of the nervous system in chronic renal failure (CRF) as a consequence of persistent biological activities of the general uremic milieu is almost identical to its structural and functional involution during the process of physiological ageing, but disproportionate and independent of chronological age. In the hyperuremic status of CRF (urea - carbamide), forced carbamylation, as a non-enzymatic post-translational modification (NEPTM) of proteins and amino acids, by changing their biological properties and decreasing proteolysis capacity, represents pathogenetic potential of intensified molecular ageing and accelerated, pathological involution. Physiological predisposition and the exposure of neuropathy before complications of other organs and organ systems in CRF, due to the simultaneous and mutually pathogenetically related uremic lesion and the tissue and vascular segment of the nervous system, direct interest towards proteomic analytical techniques of quantification of carbamylated products as biomarkers of uremic neurotoxicity. Hypothetically, identical to the already established applications of other NEPTM products in practice, they have the potential of clinical methodology in the evaluation of uremic neuropathy and its contribution to the general prediction, but also to the change of the conventional CRF classification. In addition, the identification and therapeutic control of the substrate of accelerated involution, responsible for the amplification of not only neurological but also general degenerative processes in CRF, is attractive in the context of the well-known attitude towards aging.

Signatures of Gait Movement Variability in CKD Patients Scheduled for Hemodialysis Indicate Pathological Performance Before and After Hemodialysis: A Prospective, Observational Study

Background: The frailty status of hemodialysis patients is well-known, but the role of the therapy in the frailty process is not yet clear. Nowadays gait analysis in nephrology is neglected, although gait performance is known to be related to frailty and kidney function. We hypothesized that gait quality and physical activity level is already affected before, and does not change because of the start of hemodialysis.

Methods: Fourteen patients (72.3 ± 5.7 years old) in a pre-dialysis program underwent an instrumental gait analysis and their physical activity was monitored for a week. This protocol was repeated 3, 6, 12, and 24 months after the first hemodialysis session.

Results: At baseline, our sample showed a conservative gait with pathologic gait variability, high dual-task cost, and a sedentary lifestyle. No statistically significant change was found in any parameter in the analyzed period, but there was a tendency toward an improvement of gait quality and physical activity in the first year of treatment, and a decline in the second year.

Conclusion: Elderly patients in the pre-dialysis stage show a conservative gait, however variability was in a pathological range and did not change post-hemodialysis. This hints toward changes in the central nervous system due to the kidney disease. This finding suggests the importance of gait analysis in the early stages of renal disease in the diagnosis of changes in the nervous system due to kidney failure that affect gait. Early detection of these changes would potentially allow a prevention program tailored to this population to be developed.

Renal dysfunction is associated with decline of cognitive function in community-dwelling older adults: Korean frailty and aging cohort study

Background

Cognitive decline is common in older adults. Similarly, the prevalence of renal dysfunction is also increased in the elderly population. We conducted this study to clarify the relationship between renal dysfunction and decline of cognitive function in community-dwelling elderly population.

Methods

A cross-sectional analysis was performed using data from the Korean Frailty and Aging Cohort Study, a nationwide cohort study. Total 2847 (1333 men, 1514 women) eligible participants were enrolled for this study. The estimated glomerular filtration rate (eGFR, mL/min/1.73m²) was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. Global cognitive function was assessed with the Mini-mental State Examination-Korean version. Other domains of cognitive function were tested with the Consortium to Establish a Registry for Alzheimer’s disease and the Frontal Assessment Battery.

Results

The mean age of all participants was 76.0 ± 3.9 years and eGFR (all in mL/min/1.73 m²) was 77.5 ± 14.3. And the mean eGFR was 91.7 ± 3.2 in quartile 1, 84.9 ± 1.8 in quartile 2, 76.1 ± 3.7 in quartile 3, and 57.2 ± 10.8 in quartile 4. In baseline characteristics, participants with lower eGFR tend to have lower cognitive function scores than participant with higher eGFR. In linear regression analysis, eGFR was correlated with the word list memory (β = 0.53, P = 0.005), word list recall (β = 0.86, P < 0.001), and word list recognition (β = 0.43, P = 0.030) after adjustment of confounding variables. Moreover, after multivariate adjustment the association with cognitive impairment in quartile 2 was stronger (adjusted OR: 1.535, 95% CI: 1.111–2.120, P = 0.009), and the ORs of cognitive impairment were 1.501 (95% CI: 1.084–2.079, P = 0.014) in quartile 3 and 1.423 (95% CI: 1.022–1.983, P = 0.037) in quartile 4.

Conclusion

In older adults, the immediate, recent memory, and recognition domains were significantly related to renal function. Also, the mild renal dysfunction was independently associated with impairment of global cognitive function. These results suggest that the early stages of renal dysfunction could be an effective target to prevent worsening of cognitive impairment. Therefore, regular monitoring and early detection of mild renal dysfunction in elderly population might be needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-020-01862-8.

A Low Ankle-Brachial Index and High Brachial-Ankle Pulse Wave Velocity Are Associated with Poor Cognitive Function in Patients Undergoing Hemodialysis

Patients with end-stage renal disease (ESRD) have an increased risk of both impaired cognitive function and peripheral artery disease (PAD) than the general population. The association between PAD and dementia is recognized, but there are limited studies in patients with ESRD. The aim of this study was to evaluate the relationship between ankle-brachial index (ABI) and brachial-ankle pulse wave velocity (baPWV) and cognitive impairment in patients receiving hemodialysis (HD). We enrolled 136 prevalent HD patients (mean age 59.3 ± 10.5 years, 55.9% male). Cognitive performance was measured using the Montreal Cognitive Assessment (MoCA) and Cognitive Abilities Screening Instrument (CASI) by trained psychiatrists. Associations between the cognitive function and ABI and baPWV were assessed using multiple linear regression analysis. Compared with HD patients with ABI ≥ 0.9, patients with ABI < 0.9 had lower MoCA score (p = 0.027) and lower CASI score but did not achieve significant level (p = 0.056). In the multivariate stepwise linear regression analysis, ABI (per 0.1) was independently positively associated with the MoCA score (β coefficient = 0.62, p = 0.011) and the CASI score (β coefficient = 1.43, p = 0.026). There is a negative association between baPWV (per 100 cm/s) and CASI (β coefficient = −0.70, p = 0.009). In conclusion, a low ABI or high baPWV was associated with a lower cognitive function in HD patients.

Cognitive assessment in a predominantly Hispanic and Native American population in New Mexico and its association with kidney transplant wait-listing

The association between cognitive function and the likelihood of kidney transplant (KT) wait-listing, especially in minority populations, has not been clearly delineated. We performed a retrospective review of our pre-KT patients, who consist mainly of Hispanics and Native Americans, over a 16-month period. We collected data on baseline demographics and the Montreal Cognitive Assessment (MoCA) score, at the initial KT evaluation. We defined cognitive impairment as MoCA scores of <24. We constructed linear regression models to identify associations between baseline characteristics with MoCA scores and used Cox proportional hazards models to assess associations between MoCA score and KT wait-listing. During the study period, 154 patients completed the MoCA during their initial evaluation. Mean (standard deviation) MoCA scores were 23.9 (4.6), with 58 (38%) participants scoring <24. Advanced age, lower education and being on dialysis were associated with lower MoCA scores. For every one-point increase in MoCA, the likelihood of being wait-listed increased 1.10-fold (95% CI 1.01-1.19, P = .022). Being Native American and having kidney disease due to diabetes or hypertension were associated with longer time to wait-listing. Cognitive impairment was common in our pre-KT patients and was associated with a lower likelihood of KT wait-listing.

Does Chronic Kidney Disease-Induced Cognitive Impairment Affect Driving Safety?

PURPOSE OF REVIEW

One of the principal mechanisms by which illness can affect driving safety is by impairing cognition. Nevertheless, despite the substantial evidence demonstrating cognitive impairment in chronic kidney disease (CKD), little is known about the effects of CKD on driving safety.

OBJECTIVE

Investigate the current national medical guidelines and research literature with respect to CKD and driving safety.

SOURCES OF INFORMATION

Medline, CINAHL, PEDro, Scopus as of August 2017. The most up to date national driving guidelines and available information provided by the provincial and territorial ministries of transportation across Canada.

FINDINGS

Fives studies of driving fitness in patients with CKD have been published with minimal data available for patients at early stages of the disease. Amongst these studies, only two come from an era when modern end stage renal disease therapies were routinely provided. The first study demonstrated that 40% of 186 surveyed patients on hemodialysis felt uncomfortable driving and that 1/3 of patients were involved in motor vehicle collisions (MVC) since starting dialysis. Of the patients who felt comfortable driving, more than 75% were found to be at increased driving risk. The second study reported that 15% of patients on hemodialysis were involved in MVCs over a three year span and that the "Am I A Safe Driver" assessment tool by the American Medical Association may not capture all patients at high driving risk. Despite these alarming numbers, national guidelines place few driving restrictions on this patient population and only 3 of 11 available provincial or territorial driving forms include kidney disease as a category that physicians should consider when assessing medical fitness to drive.

LIMITATIONS

Our review is limited by the lack of randomized control studies evaluating the effects of CKD on driving safety.

IMPLICATIONS

Our review demonstrates that driving safety in this patient population remains poorly understood. The limited evidence that does exist, however, suggests that these patients are at substantial risk for unsafe driving. Future research is necessary to determine the impact of CKD-associated cognitive impairment on driving risk, and to parse out the contributions of CKD and its various treatments to driving impairment.

Dementia risk in renal dysfunction: A systematic review and meta-analysis of prospective studies

OBJECTIVE

Renal dysfunction has been linked with increased risk for cognitive impairment and dementia, but studies are conflicting. For that reason, the aim of the present systematic review and meta-analysis is to summarize the best available evidence on the prospective association between potential markers of renal dysfunction and development of cognitive impairment or dementia.

METHODS

Medline, Embase, and Cochrane Database of Systematic Reviews were searched for potential publications until August 1, 2016. Studies were eligible if they fulfilled the following criteria: population-based study, prospective design, ≥100 participants, aged ≥45 years, ≥1 year follow-up, and cognition/dementia outcomes. Where appropriate, random effects meta-analyses were conducted yielding pooled odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Twenty-two out of 8,494 abstracts fulfilled the eligibility criteria. Sufficient evidence was found for albuminuria, mixed results for estimated glomerular filtration rate (eGFR), insufficient support for cystatin C, and tentative evidence for serum creatinine and creatinine clearance. Meta-analyses of 5 studies representing 27,805 persons showed a 35% increased risk of cognitive impairment or dementia in those with albuminuria (OR 1.35, 95% CI 1.06-1.73, p = 0.015), whereas eGFR <60 mL/min/1.73 m² showed no significant association (OR 1.28, 95% CI 0.99-1.65, p = 0.063). No meta-analyses could be done for serum creatinine, creatinine clearance, or cystatin C.

CONCLUSIONS

The overall evidence for an association between renal dysfunction and cognitive impairment or dementia is modest. Evidence suggests that albuminuria is associated with higher odds of developing cognitive impairment or dementia.

Impact of Cognitive Function Change on Mortality in Renal Transplant and End-Stage Renal Disease Patients

BACKGROUND

Limited evidence from small-scale studies, mainly involving end-stage renal disease (ESRD) patients, suggests that kidney transplantation may improve cognitive function. We examined changes in cognitive function after a kidney transplant and its association with survival in advanced chronic kidney disease (CKD)/ESRD patients.

METHODS

In a prospective study design, cognitive performance of 90 patients (50.6 ± 13.1 years, 66.7% men, 27.8% blacks, 76% CKD stages 4-5) was assessed at the respective patients' residences using established neurocognitive tests.

RESULTS

Among the 90 patients, 44 received a kidney transplant (KTx group) while 46 did not (no-KTx group). After a mean follow-up of ∼19 months, there was no significant change in scores for majority of cognitive tests in either group. Older age, but not diabetes or renal function status (CKD vs. ESRD), was a determinant of poor follow-up cognitive performance. Additionally, poor attention/psychomotor speed and executive performance (as measured by Trails A and Stroop test, respectively) was associated with higher mortality over a mean follow-up of 4.7 years, even after adjustment for age, sex, diabetes, CKD or ESRD status and kidney transplant status.

CONCLUSION

Overall, cognitive function does not significantly improve after kidney transplant or significantly decline in non-transplanted, advanced CKD/ESRD patients. Poor attention, psychomotor speed and executive performance independent of transplant status were associated with higher mortality over time.

25-vitamin D, 1,25-vitamin D, parathyroid hormone, fibroblast growth factor-23 and cognitive function in men with advanced CKD: a veteran population

Abstract. Cognitive impairment is common in advanced chronic kidney disease (CKD), but little is known about its relation with abnormalities in mineral metabolism. Methods: The longitudinal association between plasma 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)2D), intact parathyroid hormone (iPTH), and fibroblast growth factor-23 (FGF-23) levels and cognitive function was assessed in 605 patients (67 ± 12 years) with advanced CKD not requiring dialysis (n = 247) or end-stage renal disease (ESRD; n = 358) who participated in the Homocysteine Study Cognitive Function Substudy (HOSTCOG)). Cognitive function was assessed using the Telephone Interview for Cognitive Status-modified (TICSm; mean follow-up 3.1 years) and associated with baseline mineral metabolite levels using linear regression analyses. Results: In unadjusted analyses, increasing log 1,25(OH)2D and decreasing log iPTH and FGF-23 levels were associated with worse cognitive status (p < 0.05). In fully adjusted multivariate analyses, the associations were no longer significant. Log 25(OH)D levels were not associated with cognitive function in unadjusted or adjusted analyses. Results were similar when analyzed by tertile or separately within CKD and ESRD groups. Conclusions: These results suggest that mineral metabolism dysregulation does not mediate the impairment in cognitive function common in advanced CKD.

Patient-reported cognitive functioning and daily functioning in chronic dialysis patients

Subjective cognitive impairment negatively affects daily functioning, health-related quality of life, and health care consumption, and is predictive of future cognitive decline in many patient populations. However, no subjective measures of multidimensional cognitive functioning have been evaluated for dialysis patients. Our purposes were to examine (1) the association between patient-reported (subjective) cognitive functioning and objective cognitive functioning and (2) the relationships between subjective and objective cognitive functioning and everyday functioning of dialysis patients. We used baseline data from an ongoing longitudinal observational study of trajectories in dialysis patients' multidimensional quality of life. One hundred thirty-five patients completed a telephone-based neuropsychological battery (Brief Test of Adult Cognition by Telephone, a measure of objective cognitive functioning), a measure of subjective cognitive functioning (Patient's Assessment of Own Functioning Inventory), and measures of everyday functioning (Activities of Daily Living [ADL] and Instrumental Activities of Daily Living [IADL] scales). After controlling for age and education, there was a modest correlation (r = 0.33, P > 0.001) between subjective and objective cognitive functioning. Multivariate logistic regression models showed subjective, but not objective, cognitive functioning was a significant predictor of both ADLs and IADLs. The findings suggest the potential clinical value of subjective measures of cognitive functioning, not to replace objective measures or diagnostic tests, but rather to optimize the meaningfulness of clinical assessment and management.

Decentralized cardiovascular autonomic control and cognitive deficits in persons with spinal cord injury

Spinal cord injury (SCI) results in motor and sensory impairments that can be identified with the American Spinal Injury Association (ASIA) Impairment Scale (AIS). Although, SCI may disrupt autonomic neural transmission, less is understood regarding the clinical impact of decentralized autonomic control. Cardiovascular regulation may be altered following SCI and the degree of impairment may or may not relate to the level of AIS injury classification. In general, persons with lesions above T1 present with bradycardia, hypotension, and orthostatic hypotension; functional changes which may interfere with rehabilitation efforts. Although many individuals with SCI above T1 remain overtly asymptomatic to hypotension, we have documented deficits in memory and attention processing speed in hypotensive individuals with SCI compared to a normotensive SCI cohort. Reduced resting cerebral blood flow (CBF) and diminished CBF responses to cognitive testing relate to test performance in hypotensive non-SCI, and preliminary evidence suggests a similar association in individuals with SCI. Persons with paraplegia below T7 generally present with a normal cardiovascular profile; however, our group and others have documented persistently elevated heart rate and increased arterial stiffness. In the non-SCI literature there is evidence supporting a link between increased arterial stiffness and cognitive deficits. Preliminary evidence suggests increased incidence of cognitive impairment in individuals with paraplegia, which we believe may relate to adverse cardiovascular changes. This report reviews relevant literature and discusses findings related to the possible association between decentralized cardiovascular autonomic control and cognitive dysfunction in persons with SCI.

Kidney Function and White Matter Disease in Young Stroke Patients

Background and Purpose—

Impaired kidney function is thought to be associated with small vessel disease, outcome, and mortality in the general stroke population. Data are limited regarding young patients. The aim of this study was to investigate the association of kidney function and white matter hyperintensities (WMHs) in young patients with first ischemic stroke.

Methods—

We analyzed 2500 young (18–55 years) patients with first-ever ischemic stroke from the prospective observational Stroke in Young Fabry Patients (SIFAP1) study with available MRI data on WMH. Of these, 2009 had available data concerning estimated glomerular filtration rate (eGFR). Kidney function was expressed as eGFR by the Modification of Diet in Renal Disease method. Deep WMHs on MRI were classified by the Fazekas score. Multivariate analysis was performed using a regression model with random effects.

Results—

Mean eGFR was 96.7 mL/min in those with WMH Grade 0 to 1 (none to mild), 90.7 mL/min in WMH Grade 2 (moderate), and 89 mL/min in WMH Grade 3 (severe). Univariate analysis revealed WMH to be associated with age ( P <0.001), hypertension ( P <0.001), cardiovascular disease ( P =0.015), overweight (body mass index >25 kg/m 2 ; P =0.013), current smoking ( P =0.044), and eGFR ( P =0.009). In multivariate analysis, age, hypertension, and eGFR remained associated with WMH severity.

Conclusions—

In young patients with acute ischemic stroke, lower eGFR values in the normal range are associated with the presence of moderate to severe WMH.

Clinical Trial Registration—

URL: http://clinicaltrials.gov . Unique Identifier: NCT00414583.

Chronic kidney disease and cognitive impairment: a systematic review and meta-analysis

BACKGROUND

Chronic kidney disease (CKD) has emerged as a possible new risk factor of cognitive impairment and dementia, but results of studies remain conflicting.

METHODS

A systematic literature research of electronic databases (MEDLINE, Cochrane Library and Goggle Scholar covering the period from 1980 to January 2012) and meta-analysis of relevant cross-sectional and longitudinal studies were conducted to assess the association of CKD and cognitive decline.

RESULTS

Most cross-sectional and longitudinal studies suggest an association between cognitive impairment and CKD. Meta-analysis of cross-sectional and longitudinal studies comprising 54,779 participants yielded an association of cognitive decline in patients with CKD compared with patients without CKD (OR 1.65, 95% CI 1.32-2.05; p < 0.001, and OR 1.39, 95% CI 1.15-1.68; p < 0.001, respectively).

CONCLUSION

This is the first meta-analysis assessing the impact of CKD on cognitive decline. Our results suggest CKD being a significant and independent somatic risk factor in the development of cognitive decline.

Increased presence of cognitive impairment in hemodialysis patients in the absence of neurological events

BACKGROUND/AIMS

Cognitive impairment (CI) is highly prevalent among hemodialysis (HD) patients and is associated with increased morbidity and mortality. The aim was to compare cognitive function in HD patients with no history of stroke or dementia and well-matched controls. Studies are required to determine the impact of HD and chronic kidney disease-specific risks on CI.

METHODS

76 outpatients (50 receiving outpatient HD and 26 with normal kidney function matched for age and comorbidity) underwent a cross-sectional observational study. HD patients were well dialyzed and had optimal hemoglobin levels. A battery of eight neuropsychological tests was used. Outcomes included assessment scores of neurocognitive testing and prevalence and subtype of CI.

RESULTS

Compared to controls, HD subjects had significantly lower composite scores for each tested cognitive domain. In each domain except memory, the percentage of subjects with impairment was significantly higher in HD subjects than controls. Differences between the groups were independent of vascular and dementia risk factors. 82% of HD subjects met criteria for CI versus 50% of controls. Non-amnestic subtype of CI was more prevalent in both groups.

CONCLUSION

Well-dialyzed HD patients with optimized hemoglobin levels and with no history of stroke or dementia performed significantly worse on multiple measures of cognition compared to controls. A higher prevalence of non-memory impairment may suggest an underlying vascular versus neurodegenerative mechanism. HD and chronic kidney disease-specific risk factors may contribute to early CI not readily detected by routine screening methods.

Cardiovascular disease and cognitive function in maintenance hemodialysis patients

BACKGROUND

Cardiovascular disease (CVD) and cognitive impairment are common in dialysis patients. Given the proposed role of microvascular disease on cognitive function, particularly cognitive domains that incorporate executive functions, we hypothesized that prevalent systemic CVD would be associated with worse cognitive performance in hemodialysis patients.

DESIGN

Cross-sectional cohort.

SETTING & PARTICIPANTS

200 maintenance hemodialysis patients without prior stroke from 5 Boston-area hemodialysis units.

PREDICTOR

CVD, defined as history of coronary disease or peripheral vascular disease.

OUTCOME

Performance on a detailed neurocognitive battery. Primary analyses quantified cognitive performance using principal components analysis to reduce cognitive tests to a processing speed/executive function domain and a memory domain. Multivariable linear regression models adjusted for age, sex, education, race, and other clinical and demographic characteristics.

RESULTS

Mean age of participants was 62 ± 18 (standard deviation) years and 75 (38%) had CVD. Individuals with CVD were older and more likely to be men, have diabetes, and be current or former smokers. In adjusted models, individuals with CVD performed 0.50 standard deviation worse (P < 0.001) on tests assessing processing speed/executive function, whereas there was no difference in performance on tests of memory. Similar results were seen assessing individual tests, with performance on the Block Design, Digit Symbol Coding, and Trail Making Tests A and B significantly associated with CVD in age-, sex-, education-, and race-adjusted analyses and approaching significance in fully adjusted models.

LIMITATIONS

CVD ascertainment dependent on patient recall and dialysis unit documentation. No brain imaging.

CONCLUSIONS

The presence of CVD is associated with worse cognitive performance on tests of processing speed and executive functioning in hemodialysis patients and identifies a high-risk population for greater difficulty with complex tasks.

Depression and cognitive function in maintenance hemodialysis patients

BACKGROUND

Both depression and cognitive impairment are common in hemodialysis patients, are associated with adverse clinical outcomes, and place an increased burden on health care resources.

STUDY DESIGN

Cross-sectional cohort.

SETTING & PARTICIPANTS

241 maintenance hemodialysis patients in the Boston, MA, area.

PREDICTOR

Depressive symptoms, defined as a Center for Epidemiological Studies Depression Scale (CES-D) score ≥16.

OUTCOME

Performance on a detailed neurocognitive battery.

RESULTS

Mean age was 63.8 years, 49.0% were women, 21.6% were African American, and median dialysis therapy duration was 13.8 months. There were 57 (23.7%) participants with significant depressive symptoms. In multivariable analysis adjusting for age, sex, education, and other comorbid conditions, participants with and without depressive symptoms performed similarly on the Mini-Mental State Examination (P = 0.4) and tests of memory. However, participants with greater depressive symptoms performed significantly worse on tests assessing processing speed, attention, and executive function, including Trail Making Test B (P = 0.02) and Digit-Symbol Coding (P = 0.01). Defining depression using a CES-D score ≥18 did not substantially change results.

LIMITATIONS

Cross-sectional design, absence of brain imaging.

CONCLUSIONS

Hemodialysis patients with a greater burden of depressive symptoms perform worse on tests of cognition related to processing speed and executive function. Further research is needed to assess the effects of treating depressive symptoms on cognitive performance in dialysis patients.

Metabolic and endocrine factors in mild cognitive impairment

Mild cognitive impairment (MCI) is a heterogeneous condition with cognitive changes between normal aging and dementia. Some forms of MCI are regarded as potential preclinical forms of dementia. The control of treatable somatic risk factors is of great relevance in patients with MCI, particularly as there is insufficient evidence for the efficacy of interventions targeting neurodegenerative processes, as used in manifest dementia. The etiology of MCI is varied including cerebrovascular risk factors and is also associated with metabolic and endocrine factors. Chronic kidney disease is a newly identified and independent risk factor for MCI. Testosterone substitution is useful if a low testosterone level is present but general screening for testosterone deficiency is not yet recommended. A relationship between MCI and vitamin D or subclinical thyroid dysfunction may exist, but the value of substitution is doubtful and requires large randomized placebo-controlled trials. Although an association between vitamin B12 deficiency or hyperhomocysteinemia and MCI is present, substitution of vitamin B12 or folate does not appear to prevent cognitive decline. Estrogen-only hormone replacement therapy may be considered only in younger postmenopausal women, but may have detrimental effects on cognitive function in older postmenopausal women. Other less familiar or unknown risk factors contributing to cognitive dysfunction should be identified as they are a potential target of prevention or intervention of MCI or dementia.

The evolving challenge of evaluating older renal transplant candidates

The demographic factor over age 65 years represents the fastest growing segment of the end-stage kidney disease, wait-listed for kidney transplant, and transplanted populations. As a result, transplant physicians are increasingly asked to evaluate candidacy in older patients. Relatively little attention has been paid to the unique aspects of the pretransplant evaluation in older persons. The natural tendency is to focus on individual comorbidities as isolated entities, such as a history of coronary heart disease, while ignoring factors more specific to the aging process itself. Assessment of the burden of comorbidity along with the application of standardized geriatric assessment tools, such as the measurement of physical and cognitive function, has the potential to refine the pretransplant evaluation process in older kidney transplant candidates.

Chronic kidney disease is associated with incident cognitive impairment in the elderly: the INVADE study

BACKGROUND

Limited data exist regarding the relationship between decreased renal function and cognitive impairment.

METHODS

A total of 3679 participants of the Intervention Project on Cerebrovascular Diseases and Dementia in the Community of Ebersberg (INVADE) composed the community-based cohort study. Measures of renal function were estimated using the Cockcroft-Gault equation and divided into normal, mild and moderate-to-severe impaired renal function (creatinine clearance >or=60, 45-59 and <45 mL/min/1.73 m(2), respectively). The main outcome measures were cognitive impairment at baseline and new cognitive impairment after a 2-year follow-up. Cognitive function was measured using the 6-Item Cognitive Impairment Test (6CIT). Multiple logistic regression analysis was used to assess the association between renal function and cognitive impairment.

RESULTS

At baseline, 396 participants (10.8%) had cognitive impairment. After the 2-year follow-up, 194 participants (6.2%) developed new cognitive impairment. The incidence of cognitive impairment across the groups with normal renal function, mild and moderate-to-severe kidney disease at baseline were 5.8, 9.9 and 21.5%, respectively. Multiple logistic regression analysis after adjustment for possible confounders including traditional cardiovascular risk factors showed a significant association for participants with moderate-to-severe kidney disease at baseline to develop new cognitive impairment after the 2-year follow-up [odds ratio: 2.14 (95% confidence interval: 1.18-3.87), P = 0.01].

CONCLUSIONS

In summary, moderate-to-severe impaired renal function is associated with incident cognitive impairment after 2 years in a large cohort of elderly subjects.

Cognitive function in chronic kidney disease

Chronic kidney disease (CKD) is a growing public health problem. The incidence of kidney failure is rising in all age groups but particularly in older adults. Individuals in all stages of CKD are at higher risk for development of cognitive impairment and this may be a major determinant in their quality of life. Furthermore, cognitive impairment is associated with an increased risk of death in dialysis patients. Cerebrovascular disease is a strong risk factor for development of cognitive impairment and vascular disease is a more likely cause of cognitive impairment than Alzheimer's disease in patients with CKD. Both traditional and nontraditional vascular risk factors are more common in CKD and dialysis patients may also be at risk for cognitive impairment via nonvascular risk factors and the hemodialysis procedure itself. Unfortunately, because risk factors for cognitive impairment in CKD have not been thoroughly ascertained, evaluation of potential treatments has been limited. Given the high prevalence of cognitive impairment in all stages of CKD, additional studies are needed to evaluate potential risk factors and treatments in this vulnerable population.

Cognitive impairment in the aging dialysis and chronic kidney disease populations: an occult burden

The high burden of cognitive impairment in hemodialysis and chronic kidney disease (CKD) patients has only recently become recognized. Up to 70% of hemodialysis patients aged 55 years and older have moderate to severe chronic cognitive impairment, yet it is largely undiagnosed. Recent studies describe the strong graded relation between estimated glomerular filtration rate and cognitive function in CKD patients. The process of conventional hemodialysis may induce recurrent episodes of acute cerebral ischemia, which, in turn, may contribute to acute decline in cognitive function during dialysis. Thus, the worst time to communicate with dialysis patients may be during the hemodialysis session. Both symptomatic and occult, subclinical ischemic cerebrovascular disease appears to play a large role in a proposed model of accelerated vascular cognitive impairment in these populations. Severe cognitive impairment or dementia among hemodialysis patients is associated with an approximately 2-fold increased risk of both mortality and dialysis withdrawal. Predialysis cognitive screening and adding dementia to the list of comorbidities on Form 2728 would provide critical information regarding the benefit versus risks of receiving dialysis. It could also improve quality of care and outcomes by raising clinicians' awareness of the potential effects of cognitive impairment on medication, fluid, and dietary compliance and the ability to make advance directive decisions among dialysis patients. Although much remains to be learned regarding the pathophysiology of cognitive impairment in kidney disease, the public health implications of this substantial burden are immediate.