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

Unraveling of Molecular Mechanisms of Cognitive Frailty in Chronic Kidney Disease: How Exercise Makes a Difference

As our population ages, the medical challenges it faces become increasingly acute, with chronic kidney disease (CKD) becoming more prevalent among older adults. Frailty is alarmingly more common in CKD patients than in the general populace, putting the elderly at high risk of both physical and cognitive decline. CKD not only accelerates physical deterioration, but also heightens vascular dysfunction, calcification, arterial rigidity, systemic inflammation, oxidative stress, and cognitive impairment. Cognitive frailty, a distinct syndrome marked by cognitive deficits caused by physiological causes (excluding Alzheimer's and other dementias), is a critical concern. Although cognitive impairment has been well-studied, the molecular mechanisms driving cognitive frailty remain largely uncharted. Comprehensive interventions, including cutting-edge pharmaceuticals and lifestyle changes, are pivotal and effective, especially in the early stages of CKD. Recent research suggests that systematic exercise could counteract cognitive decline by improving brain blood flow, boosting neuroplasticity through the brain-derived neurotrophic factor (BDNF), and by triggering the release of neurotrophic factors such as insulin-like growth factor (IGF-1). This review delves into the molecular pathways of cognitive frailty in CKD, identifies key risk factors, and highlights therapeutic approaches, particularly the potent role of exercise in enhancing cognitive health.

Association between kidney measurements and cognitive performance in patients with ischemic stroke

BACKGROUND

Individuals with chronic kidney disease (CKD) are at a substantially higher risk for stroke, which may predispose individuals to cognitive impairment. However, the association of low estimated glomerular filtration rate (eGFR) and albuminuria with poorer cognitive performance in patients with stroke is not fully understood, and the current evidence for this association is contradictory. Our aim was to retrospectively investigate whether low eGFR and albuminuria, as indicated by the urine albumin-creatinine ratio (UACR), are independently or jointly associated with worse cognitive performance in patients with ischemic stroke.

METHODS

This retrospective study included 608 patients with acute ischemic stroke. Their UACR and eGFR values were obtained from inpatient medical records. Global cognitive function was assessed with the mini-mental state exam (MMSE) and Montreal Cognitive Assessment (MoCA) one month after hospital discharge. The relationship between renal measures and cognitive performance was assessed using univariate and multiple linear regression analyses. Potential confounders included age, gender, BMI, education, diabetes and hypertension history, NIHSS score, smoking and alcohol consumption status, serum total cholesterol, triglyceride, fasting glucose, uric acid, homocysteine, systolic blood pressure, and either eGFR or UACR.

RESULTS

Patients had an average age of 66.6±4.1 years, and 48% were females. Average eGFR and UACR were 88.4±12.9 ml/min/1.73m2 and 83.6±314.2 mg/g, respectively. The number of patients with eGFR ≥90, 60-89, and <60 ml/min/1.73 m2 was 371 (61%), 207 (34%), and 30 (5%), respectively, and the percentage of patients with UACR <30 mg/g, 30-300 mg/g, and >300 mg/g was 56%, 39%, and 5%, respectively. Multivariate adjusted models showed that eGFR was independently associated with MMSE (β = -0.4; 95% CI = -0.5,-0.4; p <0.001) and MoCA (β = -0.6; 95% CI = -0.7,-0.5; p <0.001). However, UACR was not significantly correlated with MMSE or MoCA.

CONCLUSION

In patients with ischemic stroke, reduced eGFR but not albuminuria was associated with lower cognitive performance. These results show that the eGFR decline could be an effective indicator of cognitive impairment after a stroke. Therefore, regular monitoring and early detection of mild renal dysfunction in patients with acute ischemic stroke might be needed.

Chronic kidney disease and functional impairment in a longitudinal study of older adults in China

OBJECTIVES

To examine the associations of chronic kidney disease (CKD) with dynamic functional impairment among older Chinese adults.

DESIGN

This was a prospective longitudinal study.

SETTING

Data were derived from the Chinese Longitudinal Healthy Longevity Study.

PARTICIPANTS

All adults aged ≥60 years were potentially eligible. This study included 2970 participants.

PRIMARY OUTCOME MEASURES

CKD was defined as an estimated glomerular filtration rate <60 mL/min/1.73 m2. Functional performances included instrumental activities of daily living (IADL) and basic activities of daily living (BADL), which were measured using six daily activities, including eating, dressing, transferring, using the toilet, bathing and continence, and eight daily activities, including visiting neighbours, shopping, cooking, washing clothes, walking 1 km, lifting 5 kg, crouching and standing up three times and taking public transportation, respectively.

RESULTS

This study included 2970 participants, including 988 (33.60%) participants with CKD. Participants with CKD had higher IADL scores than those without CKD (β=0.895, 95% CI: 0.761 to 1.029). Furthermore, there was a significant linear trend in the association of CKD severity with the IADL score (p<0.001). Similarly, CKD was significantly associated with higher BADL scores (β=0.067, 95% CI: 0.017 to 0.118). However, only participants with moderate and advanced CKD had a higher BADL score (β=0.088 and 0.152, 95% CI: 0.006 to 0.171 and 0.019 to 0.286, respectively).

CONCLUSIONS

CKD was associated with worse functional impairment. Furthermore, there was a significant linear trend in the association of the severity of CKD with the IADL score. However, only participants with moderate and advanced CKD had higher BADL scores.

Cognitive performance is associated with glomerular filtration rate in patients with chronic kidney disease: results from the CKD-REIN cohort

BACKGROUND

Chronic kidney disease (CKD) is associated with cognitive impairment in general population. We assessed the association between kidney and cognitive functions in patients with CKD and the influence of cardiovascular (CV) risk factors, and depression on this association.

METHODS

The CKD-Renal Epidemiology and Information Network cohort included 3033 patients with CKD stages 3-4, followed for 5 years. Cognitive function was assessed with the Mini-Mental State Examination (MMSE) and estimated glomerular filtration rate (eGFR) with the CKD-Epidemiology Collaboration equation-creatinin formula. Evolution of the MMSE score over time and its association with baseline eGFR were investigated with linear mixed models. We assessed the risk of incident cognitive outcome (hospitalisation or death with relevant International Classification of Disease-10 codes), with a Cox proportional hazard model.

RESULTS

The mean age was 66.8, the mean eGFR was 33 mL/min/1.73 m² and 387 patients (13.0%) had an MMSE score below 24 at baseline. A 10 mL/min/1.73 m² decrement of baseline eGFR was associated with a mean MMSE decrease of 0.12 (95% CI 0.04 to 0.19) after adjustment for demographic characteristics, depression, CV risk factors and disease; but baseline eGFR was not associated with MMSE temporal evolution. HR for cognitive outcome during follow-up (median 2.01 years) associated with a 10 mL/min/1.73 m² decrement of baseline eGFR was 1.35 (1.07, 1.70) (p=0.01) after adjustment.

CONCLUSIONS

In patients with CKD, lower eGFR was associated with worse cognitive performance and incident cognitive events, independently of demographics, CV risk factors and depression.

TRIAL REGISTRATION NUMBER

NCT03381950.

Caffeine intake improves the cognitive performance of patients with chronic kidney disease

Objective

Cognitive impairment is a common complication of chronic kidney disease (CKD). Caffeine intake has been reported to improve cognitive performance in several studies. However, whether the benefits of caffeine intake on cognitive function apply to patients with CKD remains unknown.

Methods

We performed a retrospective cross-sectional study based on the National Health and Nutrition Examination Survey (NHANES). The data of CKD subjects and non-CKD subjects from NHANES 2011−2014 were analyzed. Propensity score matching (PSM) was performed based on age, sex, diabetes, cancer, educational level, energy intake and protein intake to select subjects. The Consortium to Establish a Registry for Alzheimer’s Disease Word Learning Test (CERAD-WL), the CERAD Word List Recall Test (CERAD-DR), the Animal Fluency Test (AF) and the Digit Symbol Substitution Test (DSST) were used, whereby the occurrence of cognitive impairment was identified. Logistic regression models were performed to evaluate the association between caffeine intake and cognitive performance in CKD and non-CKD participants. Stratified analyses according to the stage of CKD and the urinary albumin/creatinine ratio levels were performed. Plot curves were then generalized to present a non-linear relationship, and the inflection point for each non-linear model was obtained by using a recursive algorithm.

Results

Cognitive impairment was more prevalent in CKD patients than in non-CKD subjects. For CKD patients, caffeine intake was associated with higher CERAD-WL, CERAD-DR, AF and DSST scores. For non-CKD subjects, caffeine intake was associated with higher DSST scores only. Subgroup analysis revealed that caffeine only benefited the cognitive function of patients with CKD stages 2 and 3. The analysis showed non-linear relationships of caffeine intake and cognitive function for both CKD and non-CKD subjects. The inflection point of caffeine intake for CKD patients was 279 mg/day.

Conclusion

The recommended dose of caffeine intake to improve the cognitive function of CKD patients is ≤279 mg/day.

Kidney Function and Risk of Physical and Cognitive Impairment in Older Persons with Type 2 Diabetes at an Outpatient Clinic with Geriatric Assessment Implementation

PURPOSE

Diabetes is associated with an increased risk of cognitive and physical functional decline that may impede disease self-management. By incorporating cognitive and physical function assessment, this study aimed to evaluate prevalence and factors associated with cognitive and physical dysfunction in older diabetic people.

METHODS

The cross-sectional study was performed from August 1, 2017 to November 30, 2018. The patients aged 65 years or older with type 2 diabetes mellitus were enrolled and the disease was routinely evaluated by blood hemoglobin A1c (A1C), blood pressure, lipids, and kidney function measured by estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine rate (UACR). Besides, cognitive dysfunction through Mini-mental State Examination (MMSE), and functional disabilities by Activities of Daily Living (ADL) questionnaire were assessed simultaneously.

RESULTS

Among 863 patients (48.3% men) with a median age of 72.0 years (interquartile range or IQR: 67.0-78.0 years), 159 (18.5%) had cognitive impairment assessed by MMSE, while 40 (4.6%) experienced at least one problem in ADL. With different A1C stratifications, it was shown that both MMSE and ADL scores were associated with glycemic control. Patients with impaired MMSE and ADL scores were older, had lower eGFR, lower blood pressure, and higher UACR levels. After adjustment of possible confounders, it was shown that age and eGFR predicted MMSE and ADL score impairment.

CONCLUSION

By incorporating physical and cognitive function screening program into routine care at a diabetes outpatient clinic, our study found that both cognitive and physical function impairment were common in older diabetic patients, and their relevant factors, including older age, and lower eGFR. It was recommended that in older individuals with diabetes, particularly those with risk factors, an additional assessment of cognitive and physical functions can be integrated into routine clinical process to provide more comprehensive management plans.