Correlation between gut microbiome and cognitive impairment in patients undergoing peritoneal dialysis

Nutrition, cognition and chronic kidney disease: A comprehensive review of interactions and interventions

BACKGROUND

Cognitive impairment is a prevalent complication in chronic kidney disease (CKD), ranging from mild deficits in early stages to more severe conditions, such as mild cognitive impairment and dementia in advanced stages. CKD patients exhibit reduced performance in memory, attention, language, visuospatial abilities and executive functions.

RESULTS AND DISCUSSION

Contributing factors include uraemic toxins, structural brain changes, blood-brain barrier dysfunction, anaemia and comorbidities like diabetes mellitus. Malnutrition, affecting nearly half of CKD patients, exacerbates cognitive decline through inflammation, oxidative stress and protein-energy wasting. Nutritional deficiencies, particularly in protein, vitamin D, B vitamins, omega-3 fatty acids and antioxidants, are linked to impaired cognition. Emerging evidence highlights the role of the gut-brain axis, with gut-derived uraemic toxins and microbiome alterations contributing to cognitive dysfunction. Processed foods and microplastics further compound risks by promoting inflammation and neurotoxicity. Dialysis and kidney transplantation offer opportunities for cognitive recovery, though challenges remain, particularly in haemodialysis patients. Nutritional interventions, including tailored protein intake, micronutrient supplementation and dietary counselling, are critical for mitigating cognitive decline. Addressing CKD comorbidities, such as anaemia and diabetes through targeted nutritional and pharmacological strategies, improves outcomes. Integrating psychological and social support enhances quality of life, given the high prevalence of anxiety and depression in CKD patients.

CONCLUSIONS

Future research should focus on personalized nutrition, gut microbiota modulation and routine cognitive assessments to optimise care. A holistic approach combining medical, nutritional and psychosocial strategies is essential for improving cognitive and overall health in CKD patients.

Genetic and circulating biomarkers of cognitive dysfunction and dementia in CKD

Chronic kidney disease (CKD) is commonly accompanied by cognitive dysfunction and dementia, which, in turn, increase the risk of hospitalization, cardiovascular events and death. Over the last 30 years, only four studies focused on genetic markers of cognitive impairment in CKD and kidney failure (KF), indicating a significant gap in research. These studies suggest potential genetic predispositions to cognitive decline in CKD patients but also underscore the necessity for more comprehensive studies. Seventeen reports have established connections between cognitive function and kidney disease markers such as estimated glomerular filtration rate (eGFR), Cystatin C and albuminuria. A rapid eGFR decline has been associated with cognitive deterioration and vascular dementia, and mild to moderate eGFR reductions with diminished executive function in elderly men. Various biomarkers have been associated to Alzheimer's disease or dementia in CKD and KF. These include amyloid beta and phosphorylated tau proteins, uremic toxins, gut microbiota, metabolic indicators, hypertension, endothelial dysfunction, vitamins and inflammation. However, the causal relevance of these associations remains unclear. Overall, the available evidence points to a complex interplay between the different biomarkers and cognitive health in CKD patients, underscoring the need for more research to elucidate these relationships.

Association of abdominal aortic calcification with cognitive impairment in peritoneal dialysis patients

BACKGROUND

Patients on peritoneal dialysis (PD) frequently have cognitive impairment, which is linked to a poor prognosis. The purpose of this study was to determine whether abdominal aortic calcification (AAC) may have an impact on PD patients' cognitive function.

METHODS

In this cross-sectional study of 110 PD patients, cognitive function was assessed using the Montreal Cognitive Assessment (MoCA), and AAC severity was quantified via lateral lumbar radiography (Kauppila method). Participants were stratified by AAC severity into high (HAAC; score ≥ 4) and low (LAAC; score < 4) groups.

RESULTS

Cognitive impairment (MoCA < 26) was present in 65.45% of patients. The HAAC group (71.8% of cohort) exhibited distinct metabolic profiles compared to LAAC: older age (63.2 ± 9.8 vs. 47.4 ± 12.1 years, P < 0.001), higher diabetes prevalence (68.4% vs. 22.6%, P < 0.001), elevated serum phosphorus (1.62 ± 0.45 vs. 1.30 ± 0.42 mmol/L, P < 0.001), and lower diastolic blood pressure (79.2 ± 10.8 vs. 86.6 ± 13.4 mmHg, P = 0.005). Notably, HAAC patients had reduced serum creatinine (898.4 ± 251.9 vs. 1190.7 ± 243.5 µmol/L, P < 0.001) and iPTH levels (142.5 vs. 218.0 pg/mL, P = 0.011), suggesting concurrent mineral bone disorder. Multivariate analysis identified AAC severity (OR = 1.28 per 1-point increase, 95%CI = 1.09-1.50) and age (OR = 1.12/year, 95%CI = 1.06-1.19) as independent predictors of cognitive impairment.

CONCLUSION

AAC severity demonstrates a strong, dose-dependent association with cognitive dysfunction in PD patients, independent of traditional risk factors. The combination of elevated phosphorus and suppressed iPTH in high-AAC patients highlights the potential role of mineral metabolism dysregulation in both vascular calcification and neurocognitive decline.

Probiotic interventions in peritoneal dialysis: A review of underlying mechanisms and therapeutic potentials

Peritoneal dialysis (PD) is a commonly used modality for kidney replacement therapy for patients with end-stage kidney disease (ESKD). PD offers many benefits, including home-based care, greater flexibility, and preservation of residual kidney function compared to in-center hemodialysis. Nonetheless, patients undergoing PD often face significant challenges, including systemic inflammation, PD-related peritonitis, metabolic disorders, and cardiovascular issues that can negatively affect their quality of life and treatment outcomes. Recent studies have demonstrated the crucial role of the gut microbiome in overall health and treatment results, supporting the hypothesis that probiotics may bring potential benefits to the general population of ESKD patients. However, specific data on probiotic use in PD patients are limited. This opinion review aims to summarize the current knowledge on the relationship between PD and the gut microbiome and offers a novel perspective by specifically exploring how probiotic interventions could improve the outcomes of PD treatment. The review also outlines some clinical data supporting the effectiveness of probiotics in patients undergoing PD and considers the difficulties and restrictions in their application. Based on the current knowledge gaps, this study seeks to explore future research directions and their implications for clinical practice.

Dyslipidemia in Peritoneal Dialysis: Implications for Peritoneal Membrane Function and Patient Outcomes

Dyslipidemia is a common metabolic complication in patients undergoing peritoneal dialysis (PD) and has traditionally been viewed primarily in terms of cardiovascular risk. Current guidelines do not recommend initiating lipid-lowering therapy in dialysis patients due to insufficient evidence of its benefits on cardiovascular mortality. However, the impact of dyslipidemia in PD patients may extend beyond cardiovascular concerns, influencing PD-related outcomes such as the peritoneal ultrafiltration rate, residual kidney function, PD technique survival, and overall mortality. This review challenges the traditional perspective by discussing dyslipidemia's potential role in PD-related complications, which may account for the observed link between dyslipidemia and increased all-cause mortality in PD patients. It explores the pathophysiology of dyslipidemia in PD, the molecular mechanisms linking dyslipidemia to peritoneal membrane dysfunction, and summarizes clinical evidence supporting this hypothesis. In addition, this paper examines the potential for therapeutic strategies to manage dyslipidemia to improve peritoneal membrane function and patient outcomes. The review calls for future research to investigate dyslipidemia as a potential contributor to peritoneal membrane dysfunction and to develop targeted interventions for PD patients.

Gut Microbiota in Patients Receiving Dialysis: A Review

The human gut microbiota constitutes a complex community of microorganisms residing within the gastrointestinal tract, encompassing a vast array of species that play crucial roles in health and disease. The disease processes involved in chronic kidney disease (CKD) and end-stage kidney disease (ESKD) are now increasingly established to result in dysregulation of gut microbiota composition and function. Gut microbiota dysbiosis has been associated with poor clinical outcomes and all-cause mortality in patients with ESKD, particularly individuals receiving dialysis. Prior studies highlighted various factors that affect gut microbiota dysbiosis in CKD and ESKD. These include, but are not limited to, uraemic toxin accumulation, chronic inflammation, immune dysfunction, medications, and dietary restrictions and nutritional status. There is a lack of studies at present that focus on the evaluation of gut microbiota dysbiosis in the context of dialysis. Knowledge on gut microbiota changes in this context is important for determining their impact on dialysis-specific and overall outcomes for this patient cohort. More importantly, evaluating gut microbiota composition can provide information into potential targets for therapeutic intervention. Identification of specific microbial signatures may result in further development of personalised treatments to improve patient outcomes and mitigate complications during dialysis. Optimising gut microbiota through various therapeutic approaches, including dietary adjustments, probiotics, prebiotics, medications, and faecal transplantation, have previously demonstrated potential in multiple medical conditions. It remains to be seen whether these therapeutic approaches are effective within the dialysis setting. Our review aims to evaluate evidence relating to alterations in the gut microbiota of patients undergoing dialysis. A growing body of evidence pointing to the complex yet significant relationship which surrounds gut microbiota and kidney health emphasises the importance of gut microbial balance to improve outcomes for individuals receiving dialysis.

Gut Microbiome Is Related to Cognitive Impairment in Peritoneal Dialysis Patients

Gut microbiota disturbances may influence cognitive function, increasing uremic toxins and inflammation in dialysis patients; therefore, we aimed to evaluate the association of the gut microbiota profile with cognitive impairment (CI) in patients on automated peritoneal dialysis (APD). In a cross-sectional study, cognitive function was evaluated using the Montreal Cognitive Assessment in 39 APD patients and classified as normal cognitive function and CI. The gut microbiota was analyzed using the 16S rRNA gene sequencing approach. All patients had clinical, biochemical and urea clearance evaluations. Eighty-two percent of patients were men, with a mean age of 47 ± 24 years and 11 (7-48) months on PD therapy; 64% had mild CI. Patients with CI were older (53 ± 16 vs. 38 ± 14, p = 0.006) and had a higher frequency of diabetes mellitus (56% vs. 21%, p = 0.04) and constipation (7% vs. 48%, p = 0.04) and lower creatinine concentrations (11.3 ± 3.7 vs. 14.9 ± 5.4, p = 0.02) compared to normal cognitive function patients. Patients with CI showed a preponderance of S24_7, Rikenellaceae, Odoribacteraceae, Odoribacter and Anaerotruncus, while patients without CI had a greater abundance of Dorea, Ruminococcus, Sutterella and Fusobacteria (LDA score (Log10) > 2.5; p < 0.05). After glucose and age adjustment, Odoribacter was still associated with CI. In conclusion, patients with CI had a different gut microbiota characterized by the higher abundance of indole-producing and mucin-fermenting bacteria compared to normal cognitive function patients.

A mediation analysis of the role of total free fatty acids on pertinence of gut microbiota composition and cognitive function in late life depression

BACKGROUND

Extensive evidence demonstrates correlations among gut microbiota, lipid metabolism and cognitive function. However, there is still a lack of researches in the field of late-life depression (LLD). This research targeted at investigating the relationship among gut microbiota, lipid metabolism indexes, such as total free fatty acids (FFAs), and cognitive functions in LLD.

METHODS

Twenty-nine LLD patients from the Cognitive Outcome Cohort Study of Depression in Elderly were included. Cognitive functions were estimated through the Chinese version of Montreal Cognitive Assessment (MoCA). Blood samples were collected to evaluate serum lipid metabolism parameters. Fecal samples were evaluated for gut microbiota determination via 16S rRNA sequencing. Spearman correlation, linear regression and mediation analysis were utilized to explore relationship among gut microbiota, lipid metabolism and cognitive function in LLD patients.

RESULTS

Spearman correlation analysis revealed significant correlations among Akkermansia abundance, total Free Fatty Acids (FFAs) and MoCA scores (P < 0.05). Multiple regression indicated Akkermansia and total FFAs significantly predicted MoCA scores (P < 0.05). Mediation analysis demonstrated that the correlation between decreased Akkermansia relative abundance and cognitive decline in LLD patients was partially mediated by total FFAs (Bootstrap 95%CI: 0.023-0.557), accounting for 43.0% of the relative effect.

CONCLUSION

These findings suggested a significant relationship between cognitive functions in LLD and Akkermansia, as well as total FFAs. Total FFAs partially mediated the relationship between Akkermansia and cognitive functions. These results contributed to understanding the gut microbial-host lipid metabolism axis in the cognitive function of LLD.

Abnormalities in gut virome signatures linked with cognitive impairment in older adults

Multiple emerging lines of evidence indicate that the microbiome contributes to aging and cognitive health. However, the roles of distinct microbial components, such as viruses (virome) and their interactions with bacteria (bacteriome), as well as their metabolic pathways (metabolome) in relation to aging and cognitive function, remain poorly understood. Here, we present proof-of-concept results from a pilot study using datasets (n = 176) from the Microbiome in Aging Gut and Brain (MiaGB) consortium, demonstrating that the human virome signature significantly differs across the aging continuum (60s vs. 70s vs. 80+ years of age) in older adults. We observed that the predominant virome signature was enriched with bacteriophages, which change considerably with aging continuum. Analyses of interactions between phages and the host bacteriome suggest that lytic or temperate relationships change distinctly across the aging continuum, as well as cognitive impairment. Interestingly, the phage-bacteriome-metabolome interactions develop unique patterns that are distinctly linked to aging and cognitive dysfunction in older adults. The phage-bacteriome interactions affect bacterial metabolic pathways, potentially impacting older adults' health, including the risk of cognitive decline and dementia. Further comprehension of these studies could provide opportunities to target the microbiome by developing phage therapies to improve aging and brain health in older adults.