Kidney Function, Kidney Function Decline, and the Risk of Dementia in Older Adults: A Registry-Based Study

Generalized framework for identifying meaningful heterogenous treatment effects in observational studies: A parametric data-adaptive G-computation approach

There has been a renewed interest in identifying heterogenous treatment effects (HTEs) to guide personalized medicine. The objective was to illustrate the use of a step-by-step transparent parametric data-adaptive approach (the generalized HTE approach) based on the G-computation algorithm to detect heterogenous subgroups and estimate meaningful conditional average treatment effects (CATE). The following seven steps implement the generalized HTE approach: Step 1: Select variables that satisfy the backdoor criterion and potential effect modifiers; Step 2: Specify a flexible saturated model including potential confounders and effect modifiers; Step 3: Apply a selection method to reduce overfitting; Step 4: Predict potential outcomes under treatment and no treatment; Step 5: Contrast the potential outcomes for each individual; Step 6: Fit cluster modeling to identify potential effect modifiers; Step 7: Estimate subgroup CATEs. We illustrated the use of this approach using simulated and real data. Our generalized HTE approach successfully identified HTEs and subgroups defined by all effect modifiers using simulated and real data. Our study illustrates that it is feasible to use a step-by-step parametric and transparent data-adaptive approach to detect effect modifiers and identify meaningful HTEs in an observational setting. This approach should be more appealing to epidemiologists interested in explanation.

Association of body weight and serum uric acid with Alzheimer's disease biomarkers and cognitive impairment

BACKGROUND

Given the limited effective treatments for Alzheimer's disease (AD), obesity and serum uric acid (SUA) levels which are considered modifiable risk factors for dementia are of interest. However, research indicates conflicting results.

OBJECTIVE

We aimed to further investigate the association of body weight (BW) and SUA with AD biomarkers and cognitive impairment.

METHODS

Clinical data were collected from 139 adults (mean age 66.9 years) with chronic cognitive impairment. Cerebrospinal fluid (CSF) biomarkers and PET imaging were used to assess amyloid-β (A) and Tau (T) tangles load, classifying participants into AT profiles based on the results. The association of BW and SUA with AT profiles was evaluated using multivariable logistic regression, and their relationship with cognitive function (Mini-Mental State Examination (MMSE) scores) were analyzed using multivariable linear regression.

RESULTS

Lower BW levels significantly influenced the presence of Aβ positive state (A+) (p = 0.007), while SUA levels did not (p = 0.263). Higher dementia proportion (p = 0.021), lighter BW (p = 0.019), and lower mean arterial pressure (MAP) levels (p = 0.025) were associated with AD pathological progress (A-T-→A+T-→A+T+), but SUA was not observed statistically significant. Among all participants regardless of Aβ state, high education levels (p < 0.001), high BW (p = 0.010), and high SUA (p=0.036) were associated with high MMSE scores, and high serum creatinine (p = 0.003) was associated with low MMSE scores.

CONCLUSIONS

Lower BW may accelerate AD pathology and cause cognitive impairment, while SUA is not linked to AD pathological progression but protects cognitive function.

The effect of creatinine level on amyloid-β and tau plasma concentrations in a cohort of Alzheimer's disease patients without kidney disease

BACKGROUND

Alzheimer's disease (AD) is pathologically characterized by the deposition of beta-amyloid and tau-protein. Blood biomarkers (BBM) might be employed for detecting these abnormal proteins in vivo. As the kidney is an important excretory organ, a decreased renal function might affect the clearance of BBM. In this study we aimed to assess the relationship between kidney function, the levels of BBM and cognitive impairment in a cohort of patients with a biological AD diagnosis without chronic kidney disease (CKD).

METHODS

This is a retrospective cohort study on AD patients. Data regarding medical history at diagnosis (T0) were retrieved, together with the Mini-Mental State Examination (MMSE) score at T0 and after 6 months (T1). Cerebrospinal fluid and blood samples were collected and concentrations of Aβ42, Aβ40, t-Tau, and p-Tau181 were determined using commercially available kits. Kidney function was estimated through the 2021-CKD-EPI equation. To assess the effects of creatinine on our parameters of interest, we grouped patients into two groups -creatinine level <0.8 mg/dl (LOW) or ≥0.8 mg/dl (HIGH).

RESULTS

The median MMSE score decreased significantly between the two timepoints. When we assessed for differences in the parameters of interest between subgroups, we found that only Aβ42 plasma level was significantly different in the HIGH vs LOW group.

CONCLUSION

We found out that only Aβ42 plasma levels are influenced by kidney function, while the other AD biomarkers are not affected by creatinine levels or eGFR. Our findings are consistent with the hypothesis of renal clearance of Aβ isoforms.

Quantifying Cognitive Function in Diabetes: Relationships Between AD8 Scores, HbA1c Levels, and Other Diabetic Comorbidities

BACKGROUND/OBJECTIVES

Dementia associated with diabetes mellitus (DM) has been well documented in the literature, but studies utilizing early screening tools to target populations with mild cognitive dysfunction remain limited. This study aimed to investigate early cognitive decline by studying the relationships between "Ascertain Dementia 8" (AD8) questionnaire scores and glycemic control, lipid profiles, estimated glomerular filtration rate (eGFR), and the complications of diabetes.

METHODS

This case-control, cross-sectional, observational study was conducted at a medical center and an affiliated regional hospital in southern Taiwan from 30 June 2021 to 30 June 2023. Patients diagnosed with type 2 diabetes mellitus aged ≥40 years were recruited. Their past medical history, biochemical data, and AD8 score were collected at the same time.

RESULTS

The patients with glycated hemoglobin (HbA1c) levels of ≥7% had a higher risk of cognitive impairment than those with HbA1c levels of <7% (p < 0.001). The participants whose eGFR was <60 mL/min/1.73 m2 had a higher mean AD8 score compared to those with an eGFR of ≥60 mL/min/1.73 m2 (p = 0.008). The patients with a medical history of peripheral artery disease and diabetic neuropathy were also associated with a higher mean AD8 score (p < 0.001 and p = 0.017, respectively).

CONCLUSIONS

By employing the AD8 questionnaire as a sensitive screening tool, our study suggests that early cognitive decline is significantly associated with poorer glycemic control, a lower glomerular filtration rate, peripheral artery disease, and diabetic neuropathy. Early detection of these risk factors may facilitate timely interventions and tailored treatment strategies to treat or prevent cognitive dysfunction.

Kidney replacement therapies in the older person: challenges to decide the best option

A multitude of challenges exist when supporting older adults in deciding on the optimal kidney replacement therapy (KRT), including frailty, comorbidity, cognitive impairment, dialysis modality, as well as local availability of services. The combination of these factors can determine treatment outcomes and quality of life (QoL), and as such the care of older people should be tailored to take these into account. Frailty in older people with chronic kidney disease (CKD) leads to higher rates of hospitalization, increased mortality, and a diminished QoL, while cognitive impairment, present in up to 50% of people with CKD, exacerbates these challenges and affects decision making. Dialysis, particularly haemodialysis, can accelerate physical and cognitive decline in frail older adults. Conversely, peritoneal dialysis (PD) presents a home-based alternative that may better support QoL, particularly for people wanting to prioritize treatment flexibility and independence. Assisted PD programmes have emerged as a valuable option for older people who cannot manage home-based care independently, improving access to KRT. Ultimately shared decision making should be employed when discussing KRT, incorporating patient goals, prognostic awareness, and QoL measures. There is also the emerging role of the geriatrician and the need for an integrated Comprehensive Geriatric Assessment. These elements support older adults to make informed choices that align with the individuals' values and health needs. In designing future health services to meet the needs of increasing numbers of older people, there needs to be increased access to assisted PD as well as multidisciplinary working to ensure patient-focused care surrounding KRT in older adults.

Cognitive impairment in CKD patients: a guidance document by the CONNECT network

Cognitive impairment is a prevalent and debilitating complication in patients with chronic kidney disease (CKD). This position paper, developed by the Cognitive Decline in Nephro-Neurology: European Cooperative Target network, provides guidance on the epidemiology, risk factors, pathophysiology, diagnosis and clinical management of CKD-related cognitive impairment. Cognitive impairment is significantly more common in CKD patients compared with the general population, particularly those undergoing haemodialysis. The development of cognitive impairment is influenced by a complex interplay of factors, including uraemic neurotoxins, electrolytes and acid-base disorders, anaemia, vascular damage, metabolic disturbances and comorbidities like diabetes and hypertension. Effective screening and diagnostic strategies are essential for early identification of cognitive impairment utilizing cognitive assessment tools, neuroimaging and circulating biomarkers. The impact of various drug classes, including antiplatelet therapy, oral anticoagulants, lipid-lowering treatments and antihypertensive drugs, on cognitive function is evaluated. Management strategies encompass pharmacological and non-pharmacological interventions, with recommendations for optimizing cognitive function while managing CKD-related complications. This guidance highlights the importance of addressing cognitive impairment in CKD patients through early detection, careful medication management and tailored therapeutic strategies to improve patient outcomes.

Exploring the Kidney-Brain Crosstalk: Biomarkers for Early Detection of Kidney Injury-Related Alzheimer's Disease

Background

The phenomenon of "kidney-brain crosstalk" has stimulated scholarly inquiry into the correlations between kidney injury (KI) and Alzheimer's disease (AD). Nonetheless, the precise interactions and shared mechanisms between KI and AD have yet to be fully investigated. The primary goal of this study was to investigate the link between KI and AD, with a specific focus on identifying diagnostic biomarkers for KI-related AD.

Methods

The first step of the present study was to use Mendelian randomization (MR) analysis to investigate the link between KI and AD, followed by verification of in vivo and in vitro experiments. Subsequently, bioinformatics and machine learning techniques were used to identify biomarkers for KI-associated ferroptosis-related genes (FRGs) in AD, which were validated in following experiments. Moreover, the relationship between hub biomarkers and immune infiltration was assessed using CIBERSORT, and the potential drugs or small molecules associated with the core biomarkers were identified via the DGIdb database.

Results

MR analysis showed that KI may be a risk factor for AD. Experiments showed that the combination of D-galactose and aluminum chloride was found to induce both KI and AD, with ferroptosis emerging as a bridge to facilitate crosstalk between KI and AD. Besides, we identified EGFR and RELA have significant diagnostic value. These biomarkers are associated with NK_cells_resting and B_cells_memory and could be targeted for intervention in KI-related AD by treating gefitinib and plumbagin.

Conclusion

Our study elucidates that ferroptosis may be an important pathway for kidney-brain crosstalk. Notably, gefitinib and plumbagin may be therapeutic candidates for intervening in KI-associated AD by targeting EGFR and RELA.

Alzheimer's disease: a comprehensive review of epidemiology, risk factors, symptoms diagnosis, management, caregiving, advanced treatments and associated challenges

Background

Alzheimer's disease (AD) is a chronic, progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and impaired reasoning. It is the leading cause of dementia in older adults, marked by the pathological accumulation of amyloid-beta plaques and neurofibrillary tangles. These pathological changes lead to widespread neuronal damage, significantly impacting daily functioning and quality of life.

Objective

This comprehensive review aims to explore various aspects of Alzheimer's disease, including its epidemiology, risk factors, clinical presentation, diagnostic advancements, management strategies, caregiving challenges, and emerging therapeutic interventions.

Methods

A systematic literature review was conducted across multiple electronic databases, including PubMed, MEDLINE, Cochrane Library, and Scopus, from their inception to May 2024. The search strategy incorporated a combination of keywords and Medical Subject Headings (MeSH) terms such as "Alzheimer's disease," "epidemiology," "risk factors," "symptoms," "diagnosis," "management," "caregiving," "treatment," and "novel therapies." Boolean operators (AND, OR) were used to refine the search, ensuring a comprehensive analysis of the existing literature on Alzheimer's disease.

Results

AD is significantly influenced by genetic predispositions, such as the apolipoprotein E (APOE) ε4 allele, along with modifiable environmental factors like diet, physical activity, and cognitive engagement. Diagnostic approaches have evolved with advances in neuroimaging techniques (MRI, PET), and biomarker analysis, allowing for earlier detection and intervention. The National Institute on Aging and the Alzheimer's Association have updated diagnostic criteria to include biomarker data, enhancing early diagnosis.

Conclusion

The management of AD includes pharmacological treatments, such as cholinesterase inhibitors and NMDA receptor antagonists, which provide symptomatic relief but do not slow disease progression. Emerging therapies, including amyloid-beta and tau-targeting treatments, gene therapy, and immunotherapy, offer potential for disease modification. The critical role of caregivers is underscored, as they face considerable emotional, physical, and financial burdens. Support programs, communication strategies, and educational interventions are essential for improving caregiving outcomes. While significant advancements have been made in understanding and managing AD, ongoing research is necessary to identify new therapeutic targets and enhance diagnostic and treatment strategies. A holistic approach, integrating clinical, genetic, and environmental factors, is essential for addressing the multifaceted challenges of Alzheimer's disease and improving outcomes for both patients and caregivers.

Establishing a machine learning dementia progression prediction model with multiple integrated data

OBJECTIVE

Dementia is a significant medical and social issue in most developed countries. Practical tools for predicting the progression of degenerative dementia are highly valuable. Machine learning (ML) methods facilitate the construction of effective models using real-world data, which may include missing values and various integrated datasets.

METHOD

This retrospective study analyzed data from 679 patients diagnosed with degenerative dementia at Fu Jen Catholic University Hospital, who were evaluated by neurologists, psychologists and followed for over two years. Predictive variables were categorized into demographic (D), clinical dementia rating (CDR), mini-mental state examination (MMSE), and laboratory data value (LV) groups. These categories were further integrated into three subgroups (D-CDR, D-CDR-MMSE, and D-CDR-MMSE-LV). We utilized the extreme gradient boosting (XGB) model to rank the importance of variables and identify the most effective feature combination via a step-wise approach.

RESULT

The D-CDR-MMSE-LV model combination showed robust performance with an excellent area under the receiver operating characteristic curve (AUC) and the highest sensitivity value (84.66). Employing both demographic and neuropsychiatric variables, our prediction model achieved an AUC of 83.74. By incorporating additional clinical information from laboratory data and applying our proposed feature selection strategy, we constructed a model based on eight variables that achieved an AUC of 85.12 using the XGB technique.

CONCLUSION

We established a machine-learning model to monitor the progression of dementia using a limited, real-world clinical dataset. The XGB technique identified eight critical variables across our integrated datasets, potentially providing clinicians with valuable guidance.

Does Dialysis Therapy Cause Cognitive Impairment in Older Adults? A Propensity Score Matching Retrospective Study From a Japanese Long-Term Care Insurance Certification Survey

This study explored the longitudinal connection between dialysis therapy in older adults and the incidence of cognitive impairment, and trends of general abilities. We conducted a retrospective propensity score matching (PSM) analysis of data from the care-needs certification survey in City A, Japan, spanning 2017 to 2021. Our sample comprised 11 443 initially cognitively intact older adults from the baseline year 2017. Among them, individuals had received dialysis therapy at baseline, and 216 individuals were included after PSM. The dialysis group had a significantly lower incidence of cognitive impairment during follow-up than the control group (P = 0.02). The competing risk of death was significantly higher in the dialysis group than in the control group (P < .001). Both groups showed a decline in their comprehensive ability over the time. There have been several reports of a negative association between dialysis and cognitive impairment, but more detailed investigation of the longitudinal relationship may be needed. Comprehensive support remains critical for both dialysis and non-dialysis older adults.

Impaired kidney function, cerebral small vessel disease and cognitive disorders: the Framingham Heart Study

BACKGROUND AND HYPOTHESIS

It remains unclear whether the relation of chronic kidney disease (CKD) with cognitive dysfunction is independent of blood pressure (BP). We evaluated kidney function in relation to premorbid BP measurements, cerebral small vessel disease (CSVD), and incident mild cognitive impairment (MCI) and dementia in Framingham Offspring Cohort participants.

METHODS

We included Framingham Offspring participants free of dementia, attending an examination during midlife (exam cycle 6, baseline) for ascertainment of kidney function status, with brain magnetic resonance imaging late in life (exam cycles 7-9), cognitive outcome data, and available interim hypertension and BP assessments. We related CKD (estimated glomerular filtration rate <60 ml/min/1.73 m2) and albuminuria (urine albumin-to-creatinine ratio ≥30 mg/g) to CSVD markers and cognitive outcomes using multivariable regression analyses.

RESULTS

Among 2604 participants (mean age 67.4 ± 9.2, 64% women, 7% had CKD, and 9% albuminuria), albuminuria was independently associated with covert infarcts [adjusted OR, 1.55 (1.00-2.38); P = 0.049] and incident MCI and dementia [adjusted hazard ratio (HR), 1.68 (1.18-2.41); P = 0.005 and 1.71, (1.11-2.64); P = 0.015, respectively]. CKD was not associated with CSVD markers but was associated with a higher risk of incident dementia [HR, 1.53 (1.02-2.29); P = 0.041]. While albuminuria was predictive of the Alzheimer's disease subtype [adjusted HR = 1.68, (1.03-2.74); P = 0.04), CKD was predictive of vascular dementia [adjusted HR, 2.78 (1.16-6.68); P = 0.023].

CONCLUSIONS

Kidney disease was associated with CSVD and cognitive disorders in asymptomatic community dwelling participants. The relation was independent of premorbid BP, suggesting that the link between kidney and brain disease may involve additional mechanisms beyond BP-related injury.

ATN blood biomarkers are related to digital cognitive assessment in type 1 diabetes

INTRODUCTION

Associations between amyloid-tau-neurodegeneration (ATN) plasma biomarkers and cognition have not been characterized in adults with type 1 diabetes (T1D).

METHODS

Using data from participants in the Glycemic Variability and Fluctuations in Cognitive Status in Adults with T1D (GluCog) study (N = 114), we evaluated associations between phosphorylated tau (pTau)181, pTau217, β-amyloid 42/40 ratio, glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) and self-administered digital cognitive tests, adjusting for age, sex, education, comorbidities (e.g., kidney disease), and glycemic indices.

RESULTS

Higher concentrations of pTau181 and GFAP were associated with slower responses on working memory tasks (pTau181: β = 0.261; p = 0.007; GFAP: β = 0.175, p = 0.036), and higher β-amyloid 42/40 ratio was associated with better vocabulary (β = 0.260, p = 0.009).

Discussion

Digital cognitive performance was associated with several ATN plasma biomarkers in T1D adults. Prospective studies are needed to understand the utility of these biomarkers in T1D.

Highlights

There is an increase in life expectancy for individuals with type 1 diabetes (T1D).Few studies investigate the relationship between T1D and neurodegeneration.We characterize the relation between ATN plasma biomarkers and cognitive function.Digital cognitive performance was associated with plasma biomarkers in T1D adults.

Increased Blood-Brain Barrier Permeability and Cognitive Impairment in Patients With ESKD

Introduction

Chronic kidney disease (CKD) is associated with an increased risk of cognitive impairment. This cognitive impairment is associated with an increased permeability of blood-brain barrier (BBB) in rodents with CKD, linked to activation of aryl hydrocarbon receptor (AhR) by indoxyl sulphate (IS). The objective of the BREIN study was to confirm the increased BBB permeability in humans with CKD.

Method

The BREIN comparative study (NCT04328415) prospectively included patients with end-stage kidney disease (ESKD) and controls healthy volunteers matched in age, sex, and level of education to a patient. In all participants, BBB permeability was quantified by brain 99mTc-DTPA SPECT/CT as a percentage of injected activity (% IA). A battery of neurocognitive tests was performed, and serum uremic toxins accumulation and AhR activation were assessed.

Results

Fifteen patients with ESKD and 14 healthy volunteers were analyzed. Patients with ESKD had higher BBB permeability compared to controls: 0.29 ± 0.07 versus 0.14 ± 0.06 %IA, P = 0.002. Patients with ESKD displayed lower Montreal Cognitive Assessment test (MoCA) score: 22.0 ± 5.0 versus 27.3 ± 2.8, P = 0.008; impaired short-term memory (doors test): 12.5 ± 3.4 versus 16.5 ± 3.4, P = 0.005; higher Beck depression score 8.1 ± 9.1 versus 2.7 ± 3.4, P = 0.046; and slightly more daily cognitive complaints: 42.5 ± 29.3 versus 29.8 ± 14.0 P = 0.060. Patients with ESKD displayed higher IS levels (86.1 ± 48.4 vs. 3.2 ± 1.7 μmol/l, P = 0.001) and AhR activating potential (37.7 ± 17.8% vs. 24.7 ± 10.4%, P = 0.027). BBB permeability was inversely correlated with MoCA score (r = -0.60, 95% confidence interval [-0.772 to -0.339], P = 0.001) in the overall population.

Conclusion

Patients with ESKD display an increased BBB permeability compared to matched healthy volunteers. Association with uremic toxins and cognitive impairment needs to be assessed in larger cohorts of patients.

The flavonoid fisetin reduces multiple physiological risk factors for dementia

Dementia is a growing problem around the globe as the world's population continues to age. Multiple studies have identified potentially modifiable risk factors for the development of dementia suggesting that addressing some or all of these risk factors might have a significant impact on the aging population worldwide. However, this is not always as straightforward as it seems since many of these risk factors are currently treated with drugs specific to the risk factor. Moreover, since people can have multiple risk factors, addressing each of them individually could be highly problematic as it would likely lead to negative outcomes associated with polypharmacy and, in the long term, could do significant harm. A potential alternative is to identify compounds that have shown efficacy against a number of these different risk factors. As discussed in this review, there is strong evidence that the flavonol fisetin is one such compound. In animal studies it has shown efficacy against many of the risk factors that have been associated with an increased risk of developing dementia and also exhibits direct neuroprotective effects. Thus, further human research on fisetin in the context of dementia risk factors is clearly warranted.

Causal Effects of Kidney Function and Chronic Kidney Disease on Alzheimer's Disease by Analyzing Large-Scale Genome-Wide Association Study Datasets

Background

Alzheimer's disease (AD) is the leading cause of dementia. Genetic components play an important role in AD and have been widely evaluated by genome-wide association studies (GWAS) and exome sequencing, and some common and rare genetic variants have been identified. In addition to genetic factors, environment factors have a role in AD. Growing evidence from observational studies linked impaired kidney function to cognitive impairment and AD; however, there are inconsistences in these findings.

Objective

To determine the causal effects of impaired kidney function and chronic kidney disease (CKD) on AD.

Methods

Mendelian randomization (MR) methods have been widely used to infer causal associations between exposure and outcome. Here, we conducted an MR study to investigate the causal effects of impaired kidney function and CKD on the risk of AD by analyzing large-scale GWAS datasets from FinnGen and CKD Genetics (CKDGen) Consortium.

Results

We found no significant but a suggestive effect of CKD on decreased risk of AD using inverse-variance weighted (IVW) (p = 8.46E-02) and simple mode (p = 7.60E-02) methods. We identified a statistically significant effect of the estimated glomerular filtration rate (eGFR) on increased risk of AD using IVW (p = 1.11E-02), weighted median regression (p = 5.60E-03), and weighted mode (p = 2.45E-02) methods.

Conclusions

Together, our findings indicate that high eGFR levels may increase the risk of AD. These findings need to be verified in future studies.

Risk of recurrent stroke and dementia following acute stroke by changes in kidney function: results from the Perindopril Protection Against Recurrent Stroke Study

BACKGROUND

Limited data exist on the relationship between declining kidney function and cardiovascular events, dementia, and mortality in patients with a history of stroke.Thus the aims of the study were to investigate functional relationships between dynamic kidney function change and cardiovascular outcomes, and clarify whether adding kidney parameters to conventional cardiovascular risk factors improves model discrimination.

METHODS

Post hoc analysis of the Perindopril Protection Against Recurrent Stroke Study (PROGRESS) clinical trial of blood pressure lowering for the secondary prevention of stroke. We examined the association between dynamic kidney function defined as percentage change (declines of >30%, and >0 to ≤30%, and increases of ≥0 to <30%, and ≥30%) in estimated glomerular filtration rate (eGFR) over 2 years and recurrent stroke, major cardiovascular events, dementia and all-cause death over the next 2 years using Cox proportional hazard models controlling for eGFR at registration and potential confounders. Restricted cubic splines were used to assess the functional relationships. C-statistics and Net Reclassification Improvement (NRI) at 2 years were used to assess model discrimination.

RESULTS

In 4591 patients followed for a mean of approximately 2 years, 254 (5.5%) developed recurrent stroke, 391 (8.5%) had a major cardiovascular event, 221 (4.8%) developed dementia, and 271 (5.9%) died. Reverse J-like or U-like relationships were observed for percent declines in eGFR and outcomes. Using declines in eGFR of >0 to ≤30% as a reference, increased risks were evident for a greater decline (>30%) in relation to recurrent stroke [adjusted hazard ratio 1.85, 95% confidence interval (CI) 1.20-2.85], major cardiovascular event (2.24, 1.62-3.10) and all-cause death (2.09, 1.39-3.15). A larger increase (≥30%) in eGFR was also associated with a greater risk of all-cause death (1.96, 1.14-3.37). Improvements in the C-statistic were found by adding baseline eGFR and percent change compared with a model with conventional cardiovascular risk factors alone, for major cardiovascular events, dementia, and all-cause mortality.

CONCLUSION

Declining kidney function following an incident cerebrovascular event is associated with additional risk of a major cardiovascular events, dementia, and 2-year mortality. However, a large increase in kidney function was also found to be associated with a higher risk of mortality.

Heterogeneous treatment effects of sodium-glucose cotransporter 2 inhibitors on risk of dementia in people with type 2 diabetes: A population-based cohort study

INTRODUCTION

Sodium-glucose cotransporter 2 (SGLT2) inhibitors exhibit potential benefits in reducing dementia risk, yet the optimal beneficiary subgroups remain uncertain.

METHODS

Individuals with type 2 diabetes (T2D) initiating either SGLT2 inhibitor or sulfonylurea were identified from OneFlorida+ Clinical Research Network (2016-2022). A doubly robust learning was deployed to estimate risk difference (RD) and 95% confidence interval (CI) of all-cause dementia.

RESULTS

Among 35,458 individuals with T2D, 1.8% in the SGLT2 inhibitor group and 4.7% in the sulfonylurea group developed all-cause dementia over a 3.2-year follow-up, yielding a lower risk for SGLT2 inhibitors (RD, -2.5%; 95% CI, -3.0% to -2.1%). Hispanic ethnicity and chronic kidney disease were identified as the two important variables to define four subgroups in which RD ranged from -4.3% (-5.5 to -3.2) to -0.9% (-1.9 to 0.2).

DISCUSSION

Compared to sulfonylureas, SGLT2 inhibitors were associated with a reduced risk of all-cause dementia, but the association varied among different subgroups.

HIGHLIGHTS

New users of sodium-glucose cotransporter 2 (SGLT2) inhibitors were significantly associated with a lower risk of all-cause dementia as compared to those of sulfonylureas. The association varied among different subgroups defined by Hispanic ethnicity and chronic kidney disease. A significantly lower risk of Alzheimer's disease and vascular dementia was observed among new users of SGLT2 inhibitors compared to those of sulfonylureas.

Alzheimer disease blood biomarkers: considerations for population-level use

In the past 5 years, we have witnessed the first approved Alzheimer disease (AD) disease-modifying therapy and the development of blood-based biomarkers (BBMs) to aid the diagnosis of AD. For many reasons, including accessibility, invasiveness and cost, BBMs are more acceptable and feasible for patients than a lumbar puncture (for cerebrospinal fluid collection) or neuroimaging. However, many questions remain regarding how best to utilize BBMs at the population level. In this Review, we outline the factors that warrant consideration for the widespread implementation and interpretation of AD BBMs. To set the scene, we review the current use of biomarkers, including BBMs, in AD. We go on to describe the characteristics of typical patients with cognitive impairment in primary care, who often differ from the patient populations used in AD BBM research studies. We also consider factors that might affect the interpretation of BBM tests, such as comorbidities, sex and race or ethnicity. We conclude by discussing broader issues such as ethics, patient and provider preference, incidental findings and dealing with indeterminate results and imperfect accuracy in implementing BBMs at the population level.

Risks of Dementia in a General Japanese Older Population With Preserved Ratio Impaired Spirometry: The Hisayama Study

BACKGROUND

Studies on the association between preserved ratio impaired spirometry (PRISm) and dementia are limited. Indeed, PRISm has often been overlooked or ignored as an index of lung function impairment. Therefore, we investigated the association of PRISm with the risk for the development of dementia in an older Japanese population.

METHODS

A total of 1,202 community-dwelling, older Japanese participants aged ≥65 years without dementia were followed up for a median of 5.0 years. Participants were categorized by spirometry as follows: normal spirometry (FEV1/FVC ≥0.70 and FEV1 ≥80% predicted), PRISm (≥0.70 and <80%), airflow limitation (AFL) Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 (<0.70 and ≥80%), and AFL GOLD 2 to 4 (<0.70 and <80%). Hazard ratios (HRs) and their 95% confidence intervals (CIs) were computed using a Cox proportional hazards model.

RESULTS

During the follow-up period, 122 participants developed dementia. The age- and sex-adjusted incidences of dementia in the participants with normal spirometry, PRISm, AFL GOLD 1, and AFL GOLD 2 to 4 were 20.5, 37.0, 18.4, and 28.6 per 1,000 person-years, respectively. Participants with PRISm had a higher risk of dementia (HR 2.04; 95% CI, 1.19-3.49) than those with normal spirometry after adjusting for confounders. Moreover, both reduced FEV1% predicted values and FVC% predicted values were associated with the risk of dementia.

CONCLUSION

PRISm was associated with an increased risk of dementia in a general older Japanese population.

Blood biomarkers of Alzheimer's disease in the community: Variation by chronic diseases and inflammatory status

INTRODUCTION

We explored the variations of blood biomarkers of Alzheimer's disease (AD) by chronic diseases and systemic inflammation.

METHODS

We explored the association of AD blood biomarkers with chronic diseases and systemic inflammation (interleukin-6 [IL-6]), in 2366 dementia-free participants of the Swedish National Study on Aging and Care-in Kungsholmen, using quantile regression models.

RESULTS

A greater number of co-occurring chronic diseases was associated with higher concentrations of phosphorylated-tau 181 (p-tau181), total-tau (t-tau), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) (p < 0.01). Anemia, kidney, cerebrovascular, and heart diseases were associated with variations in the levels of AD blood biomarkers. Participants in the highest (vs. lowest) interleukin-6 (IL-6) tertile had higher NfL concentration. Systemic inflammation amplified the associations between several chronic diseases and p-tau181, t-tau, NfL, and GFAP.

DISCUSSION

In the community, the concentration of AD blood biomarkers varies in relation to medical conditions and systemic inflammation. Recognizing these influences is crucial for the accurate interpretation and clinical implementation of blood biomarkers.

HIGHLIGHTS

Participants with a complex clinical profile (i.e., multiple co-occurring diseases or specific disease combinations) display elevated levels of AD blood-biomarkers. Anemia, heart, cerebrovascular, and kidney diseases are associated with variations is the levels of AD blood biomarkers in cognitively intact older adults. Systemic inflammation amplifies the association between several chronic diseases and AD blood biomarkers.

Alzheimer's disease cerebrospinal fluid biomarkers and kidney function in normal and cognitively impaired older adults

INTRODUCTION

Recent Alzheimer's disease (AD) clinical trials have used cerebrospinal fluid (CSF) biomarker levels for screening and enrollment. Preliminary evidence suggests that AD risk is related to impaired renal function. The impact of kidney function on commonly used AD biomarkers remains unknown.

METHODS

Participants in studies conducted at the Goizueta Alzheimer's Disease Research Center (N = 973) had measurements of serum creatinine and CSF AD biomarkers. General linear models and individual data were used to assess the relationships between biomarkers and eGFR.

RESULTS

Lower estimated glomerular filtration rate (eGFR) was associated with lower amyloid beta (Aβ)42/tau ratio (p < 0.0001) and Aβ42 (p = 0.002) and higher tau (p < 0.0001) and p-tau (p = 0.0002). The impact of eGFR on AD biomarker levels was more robust in individuals with cognitive impairment (all p-values were < 0.005).

DISCUSSION

The association between eGFR and CSF AD biomarkers has a significant impact that varies by cognitive status. Future studies exploring this impact on the pathogenesis of AD and related biomarkers are needed.

Highlights

There is a significant association between Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarkers and both estimated glomerular filtration rate (eGFR) and mild cognitive impairment (MCI).Kidney function influences CSF biomarker levels in individuals with normal cognitive function and those with MCI.The impact of kidney function on AD biomarker levels is more pronounced in individuals with cognitive impairment.The variation in CSF tau levels is independent of cardiovascular factors and is likely directly related to kidney function.Tau may have a possible role in both kidney and cognitive function.

Association of periodontal disease treatment with mortality in patients with dementia: a population-based retrospective cohort study (2002-2018)

Dementia is one of the leading causes of death worldwide. In this study, we analyzed the association of periodontal treatment with the risk of death in patients with dementia. The analyzed data were obtained by linking the National Health Insurance Corporation claims data between 2002 and 2018 to the Statistics Korea death registry. In total, 1,131,406 patients with dementia aged ≥ 65 years had undergone dental treatment during the study period. Time-dependent Cox proportional hazards model was performed. The mortality rate was approximately 10% among the patients with dementia. The 17-years cumulative survival rates for patients who received periodontal treatment and their untreated counterparts were 83.5% and 71.5%, respectively. The crude hazard ratio of the periodontal group was approximately twice as high as that of the non-periodontal group (1.99; P < 0.001). Furthermore, in the regression model that was adjusted for socio-demographic variables and systematic chronic diseases, the risk of death in the non-periodontal group was approximately 1.83 times higher than that of the periodontal group (P < 0.00). These findings suggest that preventive periodontal treatment may decrease mortality risk in older people with dementia.

Menopausal hormone therapy and risk for dementia in women with CKD: A nationwide observational cohort study

AIM

The risk for dementia is increased in postmenopausal women. The incidences of premature menopause and dementia have increased in patients with chronic kidney disease (CKD). The potential benefits of hormone replacement therapy (HRT) on cognitive function may be a more critical issue for patients with CKD.

METHODS

Women aged >40 years with or without HRT were identified using the 2009 National Health Screening Questionnaire. Women who were newly diagnosed with CKD between 2009 and 2013 were enrolled. HRT was used as an exposure variable, and participants were followed from the day CKD was diagnosed to December 2019. The hazard ratio (HR) for dementia was evaluated using Cox proportional hazards regression analysis.

RESULTS

We included 755 426 postmenopausal women with CKD. The median follow-up period was 7.3 (IQR, 5.8-8.7) years. All-cause dementia, Alzheimer's disease, and vascular dementia occurred in 107 848 (14.3%), 87 833 (11.6%), and 10 245 (1.4%) women, respectively. HRT was significantly associated with a lower risk for dementia in the adjusted Cox regression model (all-cause dementia: HR 0.80; 95% confidence interval [CI] 0.78-0.82; p < 0.001; Alzheimer's disease: HR 0.80; 95% CI 0.77-0.82; p < 0.001; vascular dementia: HR 0.80; 95% CI 0.74-0.87; p < 0.001).

CONCLUSIONS

HRT was significantly associated with a lower risk for CKD-related cognitive dysfunction in postmenopausal women. Prospective studies are needed to determine whether HRT lowers the risk for dementia in menopausal women with CKD.

Effects of Hepatorenal Function on Urinary Alzheimer-Associated Neuronal Thread Protein: A Laboratory-Based Cross-Sectional Study Among the Older Chinese Population

Background

Urinary Alzheimer-associated neuronal thread protein (AD7c-NTP) is a biomarker for the early diagnosis of Alzheimer's disease (AD). It remains unclear whether hepatorenal function affects the urinary AD7c-NTP level.

Objective

To evaluate the effects of hepatorenal function on urinary AD7c-NTP level.

Methods

We enrolled 453 participants aged 60-100 years. An automated chemistry analyzer was used to determine the indicators of serum hepatorenal function. Enzyme-linked immunosorbent assay was used to measure the urinary AD7c-NTP level.

Results

Spearman's correlation analysis showed a negative correlation between urinary AD7c-NTP levels and indicators of hepatorenal function, including albumin (r = -0.181, p < 0.001), albumin/globulin ratio (r = -0.224, p < 0.001), cholinesterase (r = -0.094, p = 0.046), total carbon dioxide (r = -0.102, p = 0.030), and glomerular filtration rate (r = -0.260, p < 0.001), as well as a positive correlation with globulin (r = 0.141, p = 0.003), aspartate transaminase (r = 0.186, p < 0.001), blood urine nitrogen (r = 0.210, p < 0.001), creatinine (r = 0.202, p < 0.001), uric acid (r = 0.229, p < 0.001), and cystatin C (r = 0.265, p < 0.001). The least absolute shrinkage and selection operator (LASSO) regression analysis and multiple linear regression model analyses showed that the statistically significant hepatorenal indicators for predicting AD7c-NTP were A/G (p = 0.007), AST (p = 0.002), BUN (p = 0.019), and UA (p = 0.003).

Conclusions

The effects of hepatorenal indicators should be considered when using urinary AD7c-NTP levels in clinical settings.

Unlocking the role of the B7-H4 polymorphism in psoriasis: Insights into methotrexate treatment outcomes: A prospective cohort study

B7-H4 is a recently discovered member of B7 family that negatively regulates T-cell immunity, specifically Th1 and Th17 cell responses. However, its role in the pathogenesis of psoriasis has yet to be determined. This study aims to investigate the effect of B7-H4 polymorphism on the efficacy of methotrexate (MTX) and its mechanism in psoriasis. Four single nucleotide polymorphisms of B7-H4 were genotyped in 310 psoriatic patients who received 12-week MTX. The protein expression of B7-H4 in platelets was characterized using immunofluorescence staining, confocal laser scanning microscopy, and flow cytometry techniques. We found that GG genotype carriers of B7-H4 rs1935780 had a lower Psoriasis Area and Severity Index (PASI) 75 response rate and higher weight (p = 0.0245) and body mass index (p = 0.0185) than AA and AG genotype carriers. Multiple regression analysis showed that the PASI score at baseline (p = 0.01) and age at disease onset (p = 0.003) were positively correlated with PASI 75 response rate, while weight (p = 0.005) and the rs1935780 genotype (p = 0.003) were negatively associated with PASI 75 response rate. B7-H4 was expressed in the platelet plasma membrane and cytoplasm. Furthermore, the expression of B7-H4 protein in platelets was lower in good responders than in non-responders and was upregulated considerably after 12-week MTX or in vitro MTX stimulation in good responders. Collectively, these results demonstrate that psoriatic patients with GG genotype of B7-H4 rs1935780 had a poorer response to MTX. Low expression of B7-H4 protein in platelets correlated with better clinical outcomes of MTX in psoriasis.

Evaluating the effect of kidney function on brain volumes and dementia risk in the UK Biobank

OBJECTIVE

To investigate the association between kidney function with the risk of dementia and brain volumes.

METHODS

A total of 452,996 UK Biobank participants with calculated glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR) were included. We utilized Cox proportional hazards regression models and restricted cubic spline analyses to examine the relationships between kidney function and the risk of all-cause dementia (ACD), Alzheimer's disease (AD), and vascular dementia (VD). Additionally, we explored the correlations between kidney function and brain magnetic resonance indicators among 40,380 participants.

RESULTS

During a median follow-up of 12 years, 5,258 incident ACD cases were identified. The deterioration of kidney function was associated with an increased risk of ACD. When compared to eGFR ≥ 90 ml/min/1.73 m², the highest risk increase was evident for eGFRcre < 30 ml/min/1.73 m² (adjusted HR = 2.372, 95% CI: 1.444-3.897, P < 0.001), with eGFRcys showing greater significance (adjusted HR = 3.045, 95% CI: 2.212-4.191, P < 0.001), especially in relation to AD. Compared to the ACR level in the range of 3-30 mg/mmol, the category of > 30 mg/mmol was associated with an increased risk of ACD (adjusted HR = 1.720, 95% CI: 1.350-2.190, P < 0.001). Moreover, the decline in kidney function was associated with the total brain volume atrophy and reduction in certain subcortical areas.

CONCLUSIONS

Our study indicates that diminished kidney function, as evidenced by a drop in eGFR and aggravated proteinuria, elevates dementia risk. Associated brain structural changes further underpin this connection from a neuro-pathophysiological perspective.

Association of Kidney Function With Dementia and Structural Brain Differences: A Large Population-Based Cohort Study

BACKGROUND

The association between kidney function and dementia risk and the mechanisms underlying this relationship remain unclear.

METHODS

Within the UK Biobank, 191 970 dementia-free participants aged ≥60 (mean age: 64.1 ± 2.9 years) were followed for 16 years to detect incident dementia. Serum creatinine and Cystatin C were measured at baseline to calculate estimated glomerular filtration rate (eGFR, mL/min/1.73 m2). Kidney function was categorized as normal (eGFR ≥ 90), mildly impaired (60 ≤ eGFR < 90), or moderately to severely impaired (eGFR < 60). Dementia was assessed based on self-reported medical history and medical records. During the follow-up, a subsample of 12 637 participants underwent brain MRI scans. Volumes of total brain, gray matter, white matter, hippocampus, and white matter hyperintensities were assessed.

RESULTS

Over the follow-up, 5 327 (2.8%) participants developed dementia. Compared to normal kidney function, there was an increased risk of dementia with moderate to severely impaired kidney function (hazard ratio = 1.53, 95% confidence interval [CI]: 1.32-1.76) but not mildly impaired kidney function. In Laplace regression, dementia onset among people with moderate to severely impaired kidney function occurred 1.53 (95% CI: 0.98-2.08) years earlier than those with normal kidney function. Moderate to severely impaired kidney function was related to significantly lower gray matter volume (β = -0.11, 95% CI: -0.19 to -0.03), but not to other brain magnetic resonance imaging measures.

CONCLUSIONS

Impaired kidney function is associated with about 50% increased risk of dementia and anticipates dementia onset by more than 1.5 years. Brain neurodegeneration may underlie the kidney function-dementia association.

Comparing Symmetric Dimethylarginine and Amyloid-β42 as Predictors of Alzheimer's Disease Development

Background

Physicians may soon be able to diagnose Alzheimer's disease (AD) in its early stages using fluid biomarkers like amyloid. However, it is acknowledged that additional biomarkers need to be characterized which would facilitate earlier monitoring of AD pathogenesis.

Objective

To determine if a potential novel inflammation biomarker for AD, symmetric dimethylarginine, has utility as a baseline serum biomarker for discriminating prodromal AD from cognitively unimpaired controls in comparison to cerebrospinal fluid amyloid-β42 (Aβ42).

Methods

Data including demographics, magnetic resonance imaging and fluorodeoxyglucose-positron emission tomography scans, Mini-Mental State Examination and Functional Activities Questionnaire scores, and biomarker concentrations were obtained from the Alzheimer's Disease Neuroimaging Initiative for a total of 146 prodromal AD participants and 108 cognitively unimpaired controls.

Results

Aβ42 (p = 0.65) and symmetric dimethylarginine (p = 0.45) were unable to predict age-matched cognitively unimpaired controls and prodromal AD participants. Aβ42 was negatively associated with regional brain atrophy and hypometabolism as well as cognitive and functional decline in cognitively unimpaired control participants (p < 0.05) that generally decreased in time. There were no significant associations between Aβ42 and symmetric dimethylarginine with imaging or neurocognitive biomarkers in prodromal AD patients.

Conclusions

Correlations were smaller between Aβ42 and neuropathological biomarkers over time and were absent in prodromal AD participants, suggesting a plateau effect dependent on age and disease stage. Evidence supporting symmetric dimethylarginine as a novel biomarker for AD as a single measurement was not found.

Kidney shape statistical analysis: associations with disease and anthropometric factors

BACKGROUND

Organ measurements derived from magnetic resonance imaging (MRI) have the potential to enhance our understanding of the precise phenotypic variations underlying many clinical conditions.

METHODS

We applied morphometric methods to study the kidneys by constructing surface meshes from kidney segmentations from abdominal MRI data in 38,868 participants in the UK Biobank. Using mesh-based analysis techniques based on statistical parametric maps (SPMs), we were able to detect variations in specific regions of the kidney and associate those with anthropometric traits as well as disease states including chronic kidney disease (CKD), type-2 diabetes (T2D), and hypertension. Statistical shape analysis (SSA) based on principal component analysis was also used within the disease population and the principal component scores were used to assess the risk of disease events.

RESULTS

We show that CKD, T2D and hypertension were associated with kidney shape. Age was associated with kidney shape consistently across disease groups. Body mass index (BMI) and waist-to-hip ratio (WHR) were also associated with kidney shape for the participants with T2D. Using SSA, we were able to capture kidney shape variations, relative to size, angle, straightness, width, length, and thickness of the kidneys, within disease populations. We identified significant associations between both left and right kidney length and width and incidence of CKD (hazard ratio (HR): 0.74, 95% CI: 0.61-0.90, p < 0.05, in the left kidney; HR: 0.76, 95% CI: 0.63-0.92, p < 0.05, in the right kidney) and hypertension (HR: 1.16, 95% CI: 1.03-1.29, p < 0.05, in the left kidney; HR: 0.87, 95% CI: 0.79-0.96, p < 0.05, in the right kidney).

CONCLUSIONS

The results suggest that shape-based analysis of the kidneys can augment studies aiming at the better categorisation of pathologies associated with chronic kidney conditions.

Control Level of Type 2 Diabetes Mellitus in the Elderly Is Associated with Polypharmacy, Accompanied Comorbidities, and Various Increased Risks According to the Beers Criteria

Comorbidity rates in the geriatric population have increased because of rising life expectancy; thus, patients have had to use more medications. Type 2 diabetes mellitus, one of the most common diseases, may influence the number of drugs used in geriatric patients. The present study was designed to investigate the association between the level of type 2 DM and polypharmacy. Fifty patients with type 2 diabetes over the age of 65 were included according to the inclusion criteria; 23 were well-controlled and 27 had poorly controlled diabetes. The groups were similar in terms of age, sex, WBC, Hb, Plt, AST, ALT, serum creatinine, fasting glucose, and eGFR levels. Patients with HbA1c values above 7.5 were classified as poorly controlled diabetes patients, and those below were considered well-controlled diabetes patients and were evaluated for inappropriate medication use. The number of medications used daily by the cases (p < 0.001), the number of concomitant diseases (p = 0.001), and the number of increased risks according to the Beers Criteria (p = 0.02) were observed to be high in poorly controlled type 2 diabetes mellitus subjects. HbA1c levels were related to the number of medications (r = 0.4, p = 0.004), comorbidities (r = 0.28, p = 0.04), and the number of increased risks according to the Beers Criteria (r = 0.31, p = 0.014). In conclusion, the number of medications used in patients with poorly controlled type 2 diabetes mellitus was found to be more elevated than in individuals with well-controlled type 2 diabetes mellitus. The HbA1c values varied among patients regarding polypharmacy, comorbidities, and increased risks according to the Beers Criteria.

Understanding Cognitive Deficits in People with High Blood Pressure

High blood pressure is associated with an elevated risk of dementia. However, much less is known about how high blood pressure is related to cognitive deficits in domains including episodic memory, semantic verbal fluency, fluid reasoning, and numerical ability. By analyzing data from 337 participants (57.39% female) with a history of clinical high blood pressure diagnosis with a mean age of 48.78 ± 17.06 years and 26,707 healthy controls (58.75% female) with a mean age of 45.30 ± 15.92 years using a predictive normative modeling approach and one-sample t-tests, the current study found that people with high blood pressure have impaired immediate (t(259) = -4.71, p < 0.01, Cohen's d = -0.08, 95% C.I. [-0.11, -0.05]) and delayed word recall (t(259) = -7.21, p < 0.01, Cohen's d = -0.11, 95% C.I. [-0.15, -0.08]) performance. Moreover, people with high blood pressure also exhibited impaired performance in the animal naming task (t(259) = -6.61, p < 0.0001, Cohen's d = -0.11, 95% C.I. [-0.15, -0.08]), and number series (t(259) = -4.76, p < 0.01, Cohen's d = -0.08, 95% C.I. [-0.11, -0.05]) and numeracy tasks (t(259) = -4.16, p < 0.01, Cohen's d = -0.06, 95% C.I. [-0.09, -0.03]) after controlling for demographic characteristics. Clinicians and health professionals should consider including these tasks as part of the neuropsychological assessment for people with high blood pressure, to detect their cognitive deficits. Moreover, they should also come up with ways to improve cognitive performance in people with high blood pressure.

Biomarkers of aging in frailty and age-associated disorders: State of the art and future perspective

According to the Geroscience concept that organismal aging and age-associated diseases share the same basic molecular mechanisms, the identification of biomarkers of age that can efficiently classify people as biologically older (or younger) than their chronological (i.e. calendar) age is becoming of paramount importance. These people will be in fact at higher (or lower) risk for many different age-associated diseases, including cardiovascular diseases, neurodegeneration, cancer, etc. In turn, patients suffering from these diseases are biologically older than healthy age-matched individuals. Many biomarkers that correlate with age have been described so far. The aim of the present review is to discuss the usefulness of some of these biomarkers (especially soluble, circulating ones) in order to identify frail patients, possibly before the appearance of clinical symptoms, as well as patients at risk for age-associated diseases. An overview of selected biomarkers will be discussed in this regard, in particular we will focus on biomarkers related to metabolic stress response, inflammation, and cell death (in particular in neurodegeneration), all phenomena connected to inflammaging (chronic, low-grade, age-associated inflammation). In the second part of the review, next-generation markers such as extracellular vesicles and their cargos, epigenetic markers and gut microbiota composition, will be discussed. Since recent progresses in omics techniques have allowed an exponential increase in the production of laboratory data also in the field of biomarkers of age, making it difficult to extract biological meaning from the huge mass of available data, Artificial Intelligence (AI) approaches will be discussed as an increasingly important strategy for extracting knowledge from raw data and providing practitioners with actionable information to treat patients.

Chronic kidney disease causes blood-brain barrier breakdown via urea-activated matrix metalloproteinase-2 and insolubility of tau protein

Chronic kidney disease (CKD) causes cognitive impairment and contributes to the overall global burden of dementia. However, mechanisms through which the kidneys and brain communicate are not fully understood. We established a CKD mouse model through adenine-induced tubulointerstitial fibrosis. Novel object recognition tests indicated that CKD decreased recognition memory. Sarkosyl-insoluble-proteomic analyses of the CKD mouse hippocampus revealed an accumulation of insoluble MAPT (microtubule-associated protein tau) and RNA-binding proteins such as small nuclear ribonucleoprotein U1 subunit 70 (SNRNP70). Additionally, there was an accumulation of Immunoglobulin G (IgG), indicating blood-brain barrier (BBB) breakdown. We identified that expressions of essential tight-junction protein claudin-5 and adherens-junction protein platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) were decreased in the brain endothelial cells of CKD mice. We determined urea as a major uremic solute that dose dependently decreased both claudin-5 and PECAM-1 expression in the mouse brain endothelial cell line bEnd.3 cells. Gelatin zymography indicated that the serum of CKD mice activated matrix metalloproteinase-2 (MMP2), while marimastat ameliorated the reduction of claudin-5 expression by urea in bEnd.3 cells. This study established a brain proteomic signature of CKD indicating BBB breakdown and insolubility of tau protein, which are pathologically linked to Alzheimer's disease. Urea-mediated activation of MMP2 was partly responsible for BBB breakdown in CKD.

Associations of Blood and Cerebrospinal Fluid Aβ and tau Levels with Renal Function

Amyloid β (Aβ) and tau play pivotal roles in the pathogenesis of Alzheimer's disease (AD). Previous studies have shown that brain-derived Aβ and tau can be cleared through transport into the periphery, and the kidneys may be vital organs involved in the clearance of Aβ and tau. However, the effects of deficiency in the clearance of Aβ and tau by the kidneys on brain AD-type pathologies in humans remain largely unknown. In this study, we first recruited 41 patients with chronic kidney disease (CKD) and 40 age- and sex-matched controls with normal renal function to analyze the associations of the estimated glomerular filtration rate (eGFR) with plasma Aβ and tau levels. To analyze the associations of eGFR with cerebrospinal fluid (CSF) AD biomarkers, we recruited 42 cognitively normal CKD patients and 150 cognitively normal controls with CSF samples. Compared with controls with normal renal function, CKD patients had higher plasma levels of Aβ40, Aβ42 and total tau (T-tau), lower CSF levels of Aβ40 and Aβ42 and higher levels of CSF T-tau/Aβ42 and phosphorylated tau (P-tau)/Aβ42. Plasma Aβ40, Aβ42, and T-tau levels were negatively correlated with eGFR. In addition, eGFR was negatively correlated with CSF levels of T-tau, T-tau/Aβ42, and P-tau/Aβ42 but positively correlated with Mini-Mental State Examination (MMSE) scores. Thus, this study showed that the decline in renal function was correlated with abnormal AD biomarkers and cognitive decline, which provides human evidence that renal function may be involved in the pathogenesis of AD.

Kidney function, albuminuria, and their modification by genetic factors and risk of incident dementia in UK Biobank

BACKGROUND

Associations between kidney function and dementia risk are inconclusive. Chronic kidney disease (CKD) severity is determined by levels of both estimated glomerular filtration rate (eGFR) and the urine albumin to creatinine ratio (ACR). However, whether there is a graded increase in dementia risk for worse eGFR in each ACR category is unclear. Also, whether genetic risk for dementia impacts the associations is unknown. The current study aims to investigate the associations between eGFR and albuminuria with dementia risk both individually and jointly, whether the associations vary by different follow-up periods, and whether genetic factors modified the associations.

METHODS

In 202,702 participants aged ≥ 60 years from the UK Biobank, Cox proportional-hazards models were used to examine the associations between eGFR and urine albumin creatinine ratio (ACR) with risk of incident dementia. GFR was estimated based on serum creatinine, cystatin C, or both. The models were restricted to different follow-up periods (< 5 years, 5-10 years, and ≥ 10 years) to investigate potential reverse causation.

RESULTS

Over 15 years of follow-up, 6,042 participants developed dementia. Decreased kidney function (eGFR < 60 ml/min/1.73m2) was associated with an increased risk of dementia (Hazard Ratio [HR] = 1.42, 95% Confidence Interval [CI] 1.28-1.58), compared to normal kidney function (≥ 90 ml/min/1.73m2). The strength of the association remained consistent when the models were restricted to different periods of follow-up. The HRs for incident dementia were 1.16 (95% CI 1.07-1.26) and 2.24 (95% CI 1.79-2.80) for moderate (3-30 mg/mmol) and severely increased ACR (≥ 30 mg/mmol) compared to normal ACR (< 3 mg/mmol). Dose-response associations were observed when combining eGFR and ACR, with those in the severest eGFR and ACR group having the greatest risk of dementia (HR = 4.70, 95% CI 2.34-9.43). APOE status significantly modified the association (p = 0.04), with stronger associations observed among participants with a lower genetic risk of dementia. There was no evidence of an interaction between kidney function and non-APOE polygenic risk of dementia with dementia risk (p = 0.42).

CONCLUSIONS

Kidney dysfunction and albuminuria were individually and jointly associated with higher dementia risk. The associations were greater amongst participants with a lower genetic risk of dementia based on APOE, but not non-APOE polygenic risk.

Exploring the Link between Chronic Kidney Disease and Alzheimer's Disease: A Longitudinal Follow-Up Study Using the Korean National Health Screening Cohort

Chronic kidney disease (CKD) and Alzheimer's disease (AD) are common chronic diseases in the elderly population. Although a relationship between CKD and the occurrence of AD has been proposed, previous research results have been disputed, and further investigation is necessary to confirm this relationship. In this longitudinal follow-up study, we examined data from the Korean National Health Insurance Service-Health Screening Cohort, consisting of 15,756 individuals with CKD and 63,024 matched controls aged ≥40 years who received health check-ups between 2002 and 2019. Overlap-weighted Cox proportional hazard regression models were exploited to calculate hazard ratios (HRs) for the association between CKD and AD. During the monitoring period, individuals with CKD had a greater incidence of AD than those without CKD (15.80 versus 12.40 per 1000 person years). After accounting for various factors, CKD was significantly associated with a 1.14-fold increased likelihood of developing AD, with a 95% confidence interval ranging from 1.08 to 1.20. In subgroup analysis, this relationship persisted irrespective of age (≥70 or <70), sex, income, smoking status, alcohol consumption, place of residence, or fasting blood glucose level. Additionally, the association between CKD and AD was still evident among patients who were overweight or obese, those with normal blood pressure or cholesterol levels, and those without any other health conditions or with a CCI score of ≥2. These results suggest that CKD could increase the probability of developing AD in the Korean adult population irrespective of demographic or lifestyle conditions. This may make it challenging to predict AD in patients with CKD, emphasizing the importance of frequent AD screening and management.

Risk of New-Onset Dementia in Patients with Chronic Kidney Disease on Statin Users: A Population-Based Cohort Study

Patients with chronic kidney disease (CKD) are at a higher risk for developing dementia than the general population. Clinical studies have investigated the effects of statin use on new-onset dementia (NOD) in patients with CKD; however, the findings are inconsistent. This study examines the association between the use of statins and NOD in patients with CKD. We conducted a nationwide retrospective cohort study using the Taiwan Health Insurance Review and Assessment Service database (2003-2016). The primary outcome assessed the risk of incident dementia by estimating the hazard ratios and 95% confidence intervals. Therefore, multiple Cox regression models were conducted to analyse the association between statin use and NOD in patients with CKD. There were 24,090 participants with statin use and 28,049 participants without statin use in patients with new-diagnosed CKD; the NOD event was 1390 and 1608, respectively. There was a trend of reduction association between statin users and NOD events after adjusted sex, age, comorbidities, and concurrent medication (adjusted HR 0.93, 95% CI 0.87 to 1.00) in the 14 years of the follow-up. Sensitivity test for the propensity score 1:1 matched analyses showed similar results (adjusted HR 0.91, 95% CI 0.81 to 1.02). The subgroup analysis also identified the use of statins as having a trend against developing NOD in patients with hypertension. In conclusion, statin therapy may effectively reduce the risk of NOD in patients with CKD. More studies are needed to credibly evaluate the effects of statin therapy on the prevention of NOD in patients with CKD.

The adjusted impact of different severities of acute exacerbations and medications on the risk of developing dementia in COPD patients

BACKGROUND

Although a relationship between chronic obstructive pulmonary disease (COPD) and dementia has been reported, the initial severity upon emergency department (ED) visits and the medications used have not been well evaluated as risk factors for increased dementia occurrence. We aimed to analyze the risks of dementia development over 5 years among patients with COPD compared to matched controls (primary) and the impact of different severities of acute exacerbations (AEs) of COPD and medications on the risk of dementia development among COPD patients (secondary).

METHOD

This study used the Taiwanese government deidentified health care database. We enrolled patients during the 10-year study period (January 1, 2000, to December 31, 2010), and each patient was followed up for 5 years. Once these patients received a diagnosis of dementia or died, they were no longer followed up. The study group included 51,318 patients who were diagnosed with COPD and 51,318 matched (in terms of age, sex, and the number of hospital visits) non-COPD patients from the remaining patients as the control group. Each patient was followed up for 5 years to analyze the risk of dementia with Cox regression analysis. Data on medications (antibiotics, bronchodilators, corticosteroids) and severity at the initial ED visit (ED treatment only, hospital admission, or ICU admission) were collected for both groups, as well as demographics and baseline comorbidities, which were considered confounding factors.

RESULTS

In the study and control groups, 1,025 (2.0%) and 423 (0.8%) patients suffered from dementia, respectively. The unadjusted HR for dementia was 2.51 (95% CI: 2.24-2.81) in the study group. Bronchodilator treatment was associated with the HRs, especially among those who received long-term (> 1 month) treatment (HR = 2.10, 95% CI: 1.91-2.45). Furthermore, among 3,451 AE of COPD patients who initially visited the ED, patients who required ICU admission (n = 164, 4.7%) had a higher risk of dementia occurrence (HR = 11.05, 95% CI: 7.77-15.71).

CONCLUSION

Bronchodilator administration might be associated with a decreased risk of dementia development. More importantly, patients who suffered AEs of COPD and initially visited the ED and required ICU admission had a higher risk of developing dementia.

Population-Based Mini-Mental State Examination Norms in Adults of Mexican Heritage in the Cameron County Hispanic Cohort

BACKGROUND

Accurately identifying cognitive changes in Mexican American (MA) adults using the Mini-Mental State Examination (MMSE) requires knowledge of population-based norms for the MMSE, a scale which has widespread use in research settings.

OBJECTIVE

To describe the distribution of MMSE scores in a large cohort of MA adults, assess the impact of MMSE requirements on their clinical trial eligibility, and explore which factors are most strongly associated with their MMSE scores.

METHODS

Visits between 2004-2021 in the Cameron County Hispanic Cohort were analyzed. Eligible participants were ≥18 years old and of Mexican descent. MMSE distributions before and after stratification by age and years of education (YOE) were assessed, as was the proportion of trial-aged (50-85- year-old) participants with MMSE <24, a minimum MMSE cutoff most frequently used in Alzheimer's disease (AD) clinical trials. As a secondary analysis, random forest models were constructed to estimate the relative association of the MMSE with potentially relevant variables.

RESULTS

The mean age of the sample set (n = 3,404) was 44.4 (SD, 16.0) years old and 64.5% female. Median MMSE was 28 (IQR, 28-29). The percentage of trial-aged participants (n = 1,267) with MMSE <24 was 18.6%; 54.3% among the subset with 0-4 YOE (n = 230). The five variables most associated with the MMSE in the study sample were education, age, exercise, C-reactive protein, and anxiety.

CONCLUSION

The minimum MMSE cutoffs in most phase III prodromal-to-mild AD trials would exclude a significant proportion of trial-aged participants in this MA cohort, including over half of those with 0-4 YOE.

The kidney-brain pathogenic axis in severe falciparum malaria

Severe falciparum malaria is a medical emergency and a leading cause of death and neurodisability in endemic areas. Common complications include acute kidney injury (AKI) and cerebral malaria, and recent studies have suggested links between kidney and brain dysfunction in Plasmodium falciparum infection. Here, we review these new findings and present the hypothesis of a pivotal pathogenic crosstalk between the kidneys and the brain in severe falciparum malaria. We highlight the evidence of a role for distant organ involvement in the development of cerebral malaria and subsequent neurocognitive impairment post-recovery, describe the challenges associated with current diagnostic shortcomings for both AKI and brain involvement in severe falciparum malaria, and explore novel potential therapeutic strategies.

CKD, Brain Atrophy, and White Matter Lesion Volume: The Japan Prospective Studies Collaboration for Aging and Dementia

Rationale & Objective

Chronic kidney disease, defined by albuminuria and/or reduced estimated glomerular filtration rate (eGFR), has been reported to be associated with brain atrophy and/or higher white matter lesion volume (WMLV), but there are few large-scale population-based studies assessing this issue. This study aimed to examine the associations between the urinary albumin-creatinine ratio (UACR) and eGFR levels and brain atrophy and WMLV in a large-scale community-dwelling older population of Japanese.

Study Design

Population-based cross-sectional study.

Setting & Participants

A total of 8,630 dementia-free community-dwelling Japanese aged greater than or equal to 65 years underwent brain magnetic resonance imaging scanning and screening examination of health status in 2016-2018.

Exposures

UACR and eGFR levels.

Outcomes

The total brain volume (TBV)-to-intracranial volume (ICV) ratio (TBV/ICV), the regional brain volume-to-TBV ratio, and the WMLV-to-ICV ratio (WMLV/ICV).

Analytical Approach

The associations of UACR and eGFR levels with the TBV/ICV, the regional brain volume-to-TBV ratio, and the WMLV/ICV were assessed by using an analysis of covariance.

Results

Higher UACR levels were significantly associated with lower TBV/ICV and higher geometric mean values of the WMLV/ICV (P for trend = 0.009 and <0.001, respectively). Lower eGFR levels were significantly associated with lower TBV/ICV, but not clearly associated with WMLV/ICV. In addition, higher UACR levels, but not lower eGFR, were significantly associated with lower temporal cortex volume-to-TBV ratio and lower hippocampal volume-to-TBV ratio.

Limitations

Cross-sectional study, misclassification of UACR or eGFR levels, generalizability to other ethnicities and younger populations, and residual confounding factors.

Conclusions

The present study demonstrated that higher UACR was associated with brain atrophy, especially in the temporal cortex and hippocampus, and with increased WMLV. These findings suggest that chronic kidney disease is involved in the progression of morphologic brain changes associated with cognitive impairment.

Associations Between Plasma Klotho with Renal Function and Cerebrospinal Fluid Amyloid-β Levels in Alzheimer's Disease: The Chongqing Ageing & Dementia Study

BACKGROUND

The kidney-brain crosstalk has been involved in Alzheimer's disease (AD) with the mechanism remaining unclear. The anti-aging factor Klotho was reported to attenuate both kidney injury and AD pathologies.

OBJECTIVE

To investigate whether plasma Klotho participated in kidney-brain crosstalk in AD.

METHODS

We enrolled 33 PiB-PET-positive AD patients and 33 amyloid-β (Aβ)-negative age- and sex-matched cognitively normal (CN) controls from the Chongqing Ageing & Dementia Study (CADS). The levels of plasma Klotho, Aβ, and tau in the cerebrospinal fluid (CSF) were measured by enzyme-linked immunosorbent assay.

RESULTS

We found higher plasma Klotho and lower estimated glomerular filtration rate (eGFR) levels in AD patients compared with CN. The eGFR were positively associated with Aβ 42, Aβ 40 levels in CSF and negatively associated with CSF T-tau levels. Plasma Klotho levels were both negatively correlated with CSF Aβ 42 and eGFR. Mediation analysis showed that plasma Klotho mediated 24.96% of the association between eGFR and CSF Aβ 42.

CONCLUSION

Renal function impacts brain Aβ metabolism via the kidney-brain crosstalk, in which the plasma klotho may be involved as a mediator. Targeting Klotho to regulate the kidney-brain crosstalk provides potential therapeutic approaches for AD.

Association of Kidney Function With Development of Alzheimer Disease and Other Dementias and Dementia-Related Blood Biomarkers

IMPORTANCE

Previous research has suggested an association of kidney function with risk of Alzheimer disease (AD) or other dementias and dementia-related blood biomarkers, but a distinct association remains unclear.

OBJECTIVE

To evaluate the association of kidney function with risk of diagnosis of incident AD or dementia within 17 years and with the blood biomarkers neurofilament light (NfL), phosphorylated tau181 (p-tau181), and glial fibrillary acidic protein (GFAP).

DESIGN, SETTING, AND PARTICIPANTS

In this prospective, population-based cohort study and nested case-control study, 9940 participants in Germany were enrolled between 2000 and 2002 by their general practitioners and followed up for up to 17 years. Participants were included if information on dementia status and creatinine/cystatin C measurements were available. A subsample of participants additionally had measurements of NfL, p-tau181, and GFAP obtained from blood samples. Statistical analysis was performed from January 3 to November 25, 2022.

EXPOSURES

Impaired kidney function, based on estimated glomerular filtration rate less than 60 mL/min/1.73 m2 according to the 2021 Chronic Kidney Disease Epidemiology Collaboration creatinine-cystatin C equation.

MAIN OUTCOMES AND MEASURES

All-cause dementia, AD, and vascular dementia diagnosis, as well as log-transformed levels of NfL, p-tau181, and GFAP in blood.

RESULTS

Of 6256 participants (3402 women [54.4%]; mean [SD] age at baseline, 61.7 [6.6] years), 510 received an all-cause dementia diagnosis within 17 years of baseline. The dementia-related blood biomarker nested case-control sample included 766 participants. After adjusting for age and sex, impaired kidney function at baseline was not associated with a higher risk of all-cause dementia (hazard ratio [HR], 0.95; 95% CI, 0.69-1.29), AD (HR, 0.94; 95% CI, 0.55-1.63), or vascular dementia diagnosis (HR, 1.06; 95% CI, 0.65-1.70) within 17 years. In the cross-sectional analysis, after adjusting for age and sex, impaired kidney function was significantly associated with NfL and p-tau181 levels in blood (NfL: β = 0.47 and P < .001; p-tau181: β = 0.21 and P = .003). After adjusting for age and sex, significant associations with GFAP levels were evident only among men (men: β = 0.31 and P = .006; women: β = -0.12 and P = .11).

CONCLUSIONS AND RELEVANCE

In this population-based study of community-dwelling adults, reduced kidney function was associated with increased levels of dementia-related blood biomarkers but not increased dementia risk. Kidney function might influence the accuracy of dementia-related blood biomarkers and should be considered in clinical translation.

Association between cholinesterase inhibitors and kidney function decline in patients with Alzheimer's dementia

Preclinical evidence shows that activation of the cholinergic anti-inflammatory pathway (CAP) may have direct and indirect beneficial effects on the kidney. Cholinesterase inhibitors (ChEIs) are specific Alzheimer's dementia (AD) therapies that block the action of cholinesterases and activate CAP. Here, we explored a plausible effect of ChEIs on slowing kidney function decline by comparing the risk of CKD progression among patients with newly diagnosed AD that initiated ChEI or not within 90 days. Using complete information of routine serum creatinine tests, we evaluated changes in estimated glomerular filtration rate (eGFR) and defined the outcome of chronic kidney disease (CKD) progression as the composite of an eGFR decline of over 30%, initiation of dialysis/transplant or death attributed to CKD. A secondary outcome was death. Inverse probability of treatment-weighted Cox regression was used to estimate hazard ratios. Among 11, 898 patients, 6,803 started on ChEIs and 5,095 did not. Mean age was 80 years (64% women) and the mean eGFR was 68 ml/min/1.73m². During a median 3.0 years of follow-up, and compared to non-use, ChEI use was associated with 18% lower risk of CKD progression (1,231 events, adjusted hazard ratio 0.82; 95% confidence interval 0.71-0.96) and a 21% lower risk of death (0.79; 0.72-0.86). Results were consistent across subgroups, ChEI subclasses and after accounting for competing risks. Thus, in patients with AD undergoing routine care, use of ChEI (vs no-use) was associated with lower risk of CKD progression.

Association Between Serum Cystatin C and Cognitive Decline Independently from Creatinine: Evidence from Two Nationally Representative Aging Cohorts

BACKGROUND

Studies on the association between cystatin C based estimated glomerular filtration rate (eGFRcys) and cognitive outcomes yielded inconsistent results.

OBJECTIVE

The present study aimed to examine the potential association of eGFRcys with subsequent cognitive decline rate.

METHODS

A total of 11,503 community-based participants were involved in our analyses, including 5,837 (aged 72.9±6.3; 58.6% women) in the Health and Retirement Study (HRS) from the US and 5,666 (aged 58.1±9.2; 49.0% women) in the China Health and Retirement Longitudinal Study (CHARLS). The association of eGFRcys with subsequent cognitive decline rate was evaluated by linear mixed models.

RESULTS

During 85,266 person-years of follow-up, both baseline elevated serum cystatin C (-0.048 standard deviation [SD]/year per mg/L; 95% confidence interval [CI], -0.060 to -0.036; p < 0.001) and decreased eGFRcys (0.026 SD/year per 30 mL/min/1.73m2; 95% CI, 0.020 to 0.032; p < 0.001) were associated with faster cognitive decline rate after full adjustment. Compared with those had eGFRcys ≥90 mL/min/1.73m2, participants with eGFRcys between 60 to 90 mL/min/1.73m2 (-0.012 SD/year; 95% CI, -0.020 to -0.004; p = 0.004) and those with eGFRcys <60 mL/min/1.73m2 (-0.048 SD/year; 95% CI, -0.058 to -0.039; p < 0.001) experienced statistically significantly faster cognitive decline after adjustment. The associations were independent from serum creatinine/eGFRcre (eGFR that was calculated from serum creatinine).

CONCLUSION

Decreased eGFRcys are significantly associated with faster cognitive decline after full adjustment, independently from serum creatinine/eGFRcre. Serum cystatin C might be a risk factor or a prodromal biomarker of cognitive decline.

Association of impaired kidney function with dementia and brain pathologies: A community-based cohort study

INTRODUCTION

The relationship between impaired kidney function (KF), dementia, and brain pathologies remains unclear.

METHODS

A total of 1354 dementia- and kidney disease-free participants including 895 with normal and 459 with impaired KF were followed from 2002 until 2020 (median [interquartile range]: 5 [2-9]) to detect incident dementia. KF was assessed at baseline and categorized as normal or impaired. Over the follow-up, 453 participants died and underwent autopsies for neuropathological assessment.

RESULTS

Compared to those with normal KF, the hazard ratios (95% confidence intervals [CIs]) of those with impaired KF was 1.48 (1.15, 1.90)/1.44 (1.10, 1.88) for dementia/Alzheimer's dementia. Furthermore, impaired KF was related to a significantly higher burden of cerebral amyloid angiopathy (CAA; odds ratio = 1.96, 95% CI: 1.17, 3.30), but not to other brain pathologies.

DISCUSSION

Impaired KF is associated with an increased risk of dementia and Alzheimer's dementia. CAA may underlie, in part, this association.

HIGHLIGHTS

Impaired kidney function (KF) was associated with higher dementia and Alzheimer's dementia risk. Impaired KF anticipated dementia and Alzheimer's dementia onset by more than 1.5 years. Impaired KF was significantly related to a higher burden of cerebral amyloid angiopathy (CAA) but not to other brain pathologies.

Kidney function and risk of dementia: Observational study, meta-analysis, and two-sample mendelian randomization study

Whether impaired kidney function is associated with increased risk of developing dementia is unclear. We investigated the association between estimated glomerular filtration rate (eGFR) and dementia. Using a triangulation approach, we performed (1) a prospective study in 90,369 Danes from the Copenhagen General Population Study (CGPS), (2) a meta-analysis in 468,699 Scandinavians (including CGPS) and (3) a two-sample Mendelian randomization study in 218,792-1,004,040 Europeans using summary data from largest publicly available genome wide association studies (GWASs). During up to 15 years of follow-up (CGPS), 2,468 individuals developed dementia. Age and sex standardized percentile of eGFR below versus above the median conferred a multifactorially adjusted hazard ratio of 1.09 (95% confidence interval: 1.01-1.18). In meta-analysis, random-effects risk of dementia was 1.14 (1.06-1.22) for mildly decreased eGFR (60-90 mL/min/1.73 m²), 1.31 (0.92-1.87) for moderately decreased eGFR (30-59 mL/min/1.73 m²) and 1.91 (1.21-3.01) for severely decreased eGFR (< 30 mL/min/1.73 m²), compared to reference eGFR (> 90 mL/min/1.73 m²). Using directly comparable eGFR measures (log[eGFR] scaled to one standard deviation, as well as eGFR below versus above 60 mL/min/1.73 m²), we found no association with risk of dementia in observational CGPS or in Mendelian randomization analyses. In conclusion, impaired kidney function was associated with modestly increased risk of developing dementia. This was not supported by causal, genetic analyses using a Mendelian randomization approach. However, future stronger genetic instruments for kidney function and larger GWASs with more dementia cases, particularly for the vascular dementia subtype, warrant a re-evaluation of the causal hypothesis.

Kidney function and prescribed dose in middle‐aged and older patients starting selective serotonin reuptake inhibitors

Purpose

To avoid adverse drug reactions, dose reductions are recommended when prescribing selective serotonin reuptake inhibitors (SSRIs) to patients with impaired kidney function. The extent of this practice in routine clinical care is however unknown. We aimed to evaluate the starting and maintenance SSRI doses prescribed to patients stratified by levels of kidney function in real‐world practice.

Methods

Using data from the Stockholm CREAtinine Measurements (SCREAM) project, we identified 101 409 new users of antidepressants (including 52 286 SSRI users) in the region of Stockholm during 2006–2019, who were ≥50 years of age and had a recent creatinine test taken in order to estimate glomerular filtration rate (eGFR). SSRI dose reduction was defined as a prescribed SSRI dose of ≤0.5 defined daily doses, according to current recommendations. We examined the associations between eGFR and reductions in initial dose and maintenance dose of SSRIs using logistic regression models.

Results

Overall, reductions in initial and maintenance dose were observed among 54.1% and 34.1% of new SSRI users. Nevertheless, about 40% of individuals with an eGFR <30 ml/min/1.73 m² were prescribed an SSRI without dose reduction. After adjusting for age and other covariates, lower eGFR was associated with moderately higher odds of dose reduction, for both initial and maintenance dose. Compared to individuals with an eGFR of 90–104 ml/min/1.73 m², the adjusted odds ratios for those with an eGFR <30 ml/min/1.73 m² were 1.18 (95% CI: 1.03, 1.36) for initial dose reduction, and 1.49 (1.29, 1.72) for maintenance dose reduction. Stratified analyses showed stronger associations between lower eGFR and SSRI dose reduction among individuals aged 50–64 years and in those receiving prescriptions from psychiatric care.

Conclusions

Lower kidney function was moderately associated with a reduced SSRI dose, independently of age. Prescribing SSRIs to middle‐aged and older patients should not only consider patients' age but also their kidney function.