Gastrointestinal Changes and Alzheimer's Disease

Identifying progression subphenotypes of Alzheimer's disease from large-scale electronic health records with machine learning

OBJECTIVE

Identification of clinically meaningful subphenotypes of disease progression can enhance the understanding of disease heterogeneity and underlying pathophysiology. In this study, we propose a machine learning framework to identify subphenotypes of Alzheimer's disease progression based on longitudinal real-world patient records.

METHODS

The framework, dynaPhenoM, extracts coherent clinical topics across patient visits and employs a time-aware latent class analysis to characterize subphenotypes. We validated dynaPhenoM using three patient databases with a total of 3952 AD patients across the United States, demonstrating its effectiveness in revealing mild cognitive impairment (MCI) progression to AD.

RESULTS

Our study identified five subphenotypes associated with distinct organ systems for disease progression from MCI to AD, including common subtypes across cohorts-respiratory, musculoskeletal, cardiovascular, and endocrine/metabolic-as well as a cohort-specific digestive subtype.

CONCLUSION

Our study unravels the complexity and heterogeneity of the progression from MCI to AD. These findings highlight disease progression heterogeneity and can inform both diagnostic and therapeutic strategies, thereby advancing precision medicine for Alzheimer's disease.

Differential Transcriptional Programs Reveal Modular Network Rearrangements Associated with Late-Onset Alzheimer's Disease

Alzheimer's disease (AD) is a complex, genetically heterogeneous disorder. The diverse phenotypes associated with AD result from interactions between genetic and environmental factors, influencing multiple biological pathways throughout disease progression. Network-based approaches offer a way to assess phenotype-specific states. In this study, we calculated key network metrics to characterize the network transcriptional structure and organization in LOAD, focusing on genes and pathways implicated in AD pathology within the dorsolateral prefrontal cortex (DLPFC). Our findings revealed disease-specific coexpression markers associated with diverse metabolic functions. Additionally, significant differences were observed at both the mesoscopic and local levels between AD and control networks, along with a restructuring of gene coexpression and biological functions into distinct transcriptional modules. These results show the molecular reorganization of the transcriptional program occurring in LOAD, highlighting specific adaptations that may contribute to or result from cellular responses to pathological stressors. Our findings may support the development of a unified model for the causal mechanisms of AD, suggesting that its diverse manifestations arise from multiple pathways working together to produce the disease's complex clinical patho-phenotype.

Impact of 16S rRNA on Intestinal Flora Alterations and Early Diagnosis in Early Alzheimer's Disease Patients

BACKGROUND

Alzheimer's Disease (AD), a complex clinical condition, relies on neuropsychological assessments for early diagnosis. Recently, the gut-brain axis has been recognized as crucial in AD development, with dysbiosis in gut microbiota implicated in disease progression. Utilizing 16S rRNA analysis provides comprehensive monitoring of gut microbiota, potentially revealing biological markers for Early Alzheimer's Disease (EAD). Therefore, this study aimed to investigate the diagnostic impact of 16S ribosomal RNA (rRNA) on changes in intestinal flora among EAD patients.

METHODS

This study analyzed stool samples from 50 AD patients and 50 healthy controls between June 2022 and June 2023. Based on the disease stage, patients were categorized into EAD (n = 14) and Late Alzheimer's Disease (LAD) groups (n = 36). The V3-V4 region was sequenced using 16S rRNA quantitative Polymerase Chain Reaction (qPCR) to compare the composition of gut microbiota and differences in abundance among the three experimental groups.

RESULTS

The abundance and diversity of gut microbiota significantly increased in EAD patients compared to the healthy control group. Furthermore, 39 genera showed considerable variations between EAD and LAD patients and healthy controls, with notable increases in the abundance of Bryantella, Gemmiger, Desulfovibrio, Collinsella, and Odoribacter among EAD patients. Additionally, significant differences were observed across the Desulfovibrioales and Verrucomicrobiales, which could help distinguish EAD patients (Area Under the Curve (AUC) range 0.854, 0.966, p < 0.05).

CONCLUSION

16S rRNA technology can be used to identify EAD patients, with the Desulfovibrioales and Verrucomicrobiales indicators serving as potential biological markers.

Gut bacteria: an etiological agent in human pathological conditions

Through complex interactions with the host's immune and physiological systems, gut bacteria play a critical role as etiological agents in a variety of human diseases, having an impact that extends beyond their mere presence and affects the onset, progression, and severity of the disease. Gaining a comprehensive understanding of these microbial interactions is crucial to improving our understanding of disease pathogenesis and creating tailored treatment methods. Correcting microbial imbalances may open new avenues for disease prevention and treatment approaches, according to preliminary data. The gut microbiota exerts an integral part in the pathogenesis of numerous health conditions, including metabolic, neurological, renal, cardiovascular, and gastrointestinal problems as well as COVID-19, according to recent studies. The crucial significance of the microbiome in disease pathogenesis is highlighted by this role, which is comparable to that of hereditary variables. This review investigates the etiological contributions of the gut microbiome to human diseases, its interactions with the host, and the development of prospective therapeutic approaches. To fully harness the benefits of gut microbiome dynamics for improving human health, future research should address existing methodological challenges and deepen our knowledge of microbial interactions.

Correlation between Alzheimer's Disease and Gastrointestinal Tract Disorders

Alzheimer's disease is the most common cause of dementia globally. The pathogenesis is multifactorial and includes deposition of amyloid-β in the central nervous system, presence of intraneuronal neurofibrillary tangles and a decreased amount of synapses. It remains uncertain what causes the progression of the disease. Nowadays, it is suggested that the brain is connected to the gastrointestinal tract, especially the enteric nervous system and gut microbiome. Studies have found a positive association between AD and gastrointestinal diseases such as periodontitis, Helicobacter pylori infection, inflammatory bowel disease and microbiome disorders. H. pylori and its metabolites can enter the CNS via the oropharyngeal olfactory pathway and may predispose to the onset and progression of AD. Periodontitis may cause systemic inflammation of low severity with high levels of pro-inflammatory cytokines and neutrophils. Moreover, lipopolysaccharide from oral bacteria accompanies beta-amyloid in plaques that form in the brain. Increased intestinal permeability in IBS leads to neuronal inflammation from transference. Chronic inflammation may lead to beta-amyloid plaque formation in the intestinal tract that spreads to the brain via the vagus nerve. The microbiome plays an important role in many bodily functions, such as nutrient absorption and vitamin production, but it is also an important factor in the development of many diseases, including Alzheimer's disease. Both the quantity and diversity of the microbiome change significantly in patients with AD and even in people in the preclinical stage of the disease, when symptoms are not yet present. The microbiome influences the functioning of the central nervous system through, among other things, the microbiota-gut-brain axis. Given the involvement of the microbiome in the pathogenesis of AD, antibiotic therapy, probiotics and prebiotics, and faecal transplantation are being considered as possible therapeutic options.

Contribution of CNS and extra-CNS infections to neurodegeneration: a narrative review

Central nervous system infections have been suggested as a possible cause for neurodegenerative diseases, particularly sporadic cases. They trigger neuroinflammation which is considered integrally involved in neurodegenerative processes. In this review, we will look at data linking a variety of viral, bacterial, fungal, and protozoan infections to Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis and unspecified dementia. This narrative review aims to bring together a broad range of data currently supporting the involvement of central nervous system infections in the development of neurodegenerative diseases. The idea that no single pathogen or pathogen group is responsible for neurodegenerative diseases will be discussed. Instead, we suggest that a wide range of susceptibility factors may make individuals differentially vulnerable to different infectious pathogens and subsequent pathologies.

Butyrate as a potential therapeutic agent for neurodegenerative disorders

Maintaining an optimum microbial community within the gastrointestinal tract is intricately linked to human metabolic, immune and brain health. Disturbance to these microbial populations perturbs the production of vital bioactive compounds synthesised by the gut microbiome, such as short-chain fatty acids (SCFAs). Of the SCFAs, butyrate is known to be a major source of energy for colonocytes and has valuable effects on the maintenance of intestinal epithelium and blood brain barrier integrity, gut motility and transit, anti-inflammatory effects, and autophagy induction. Inducing endogenous butyrate production is likely to be beneficial for gut-brain homeostasis and for optimal neuronal function. For these reasons, butyrate has gained interest as a potential therapy for not only metabolic and immunological disorders, but also conditions related to the brain, including neurodegenerative diseases. While direct and indirect sources of butyrate, including prebiotics, probiotics, butyrate pro-drugs and glucosidase inhibitors, offer a promising therapeutic avenue, their efficacy and dosage in neurodegenerative conditions remain largely unknown. Here, we review current literature on effects of butyrate relevant to neuronal function, the impact of butyrate in a range of neurodegenerative diseases and related treatments that may have potential for the treatment of neurodegenerative diseases.

In Silico Investigation of Suillin Derived from Suillus luteus Mushroom (Agaricomycetes) Targeting Acetylcholinesterase: Docking and Virtual Screening Study

This study integrates bioinformatics and computer-aided drug discovery to assess suillin's therapeutic potential, particularly its interaction with acetylcholinesterase (AChE). Alzheimer's disease presents profound challenges, necessitating effective treatments to mitigate cognitive decline and improve patients' quality of life. Although current medications offer symptomatic relief, they often entail adverse effects and do not address the underlying disease progression. Natural sources, such as macrofungi mushrooms, hold promise for novel drug discovery due to their bioactive compounds' diverse therapeutic properties. Suillin, derived from Suillus luteus mushrooms, shows promise as a mixed-type AChE inhibitor, crucial for maintaining acetylcholine levels in neurodegenerative disorders like Alzheimer's disease. Computational docking studies reveal suillin's distinctive interactions with AChE, suggesting potential modulation of enzyme function through various bonding mechanisms. The Molinspiration drug-likeness score further supports suillin's efficacy, indicating its suitability for enzyme inhibition. By combining computational and bioinformatics approaches, this study elucidates suillin's molecular interactions and underscores its potential as a therapeutic agent.

Radio-Anatomical Assessment of Cerebellum Volume in Individuals with Alzheimer's Disease

INTRODUCTION

Alzheimer's disease is a chronic brain disease that includes memory and language disorders. This disease, which is considered the most common cause of dementia worldwide, accounts for 60-80% of all dementia cases. Recent studies suggest that the cerebellum may play a role in cognitive functions as well as motor functions.

MATERIALS AND METHODS

The study was conducted on 40 Alzheimer's patients and 40 healthy individuals. In our study, volumetric evaluation of the cerebellum was performed.

RESULTS

As expected, significant differences were found in cerebellar volume reduction in AD patients compared to healthy controls. Significant volume increase was observed in some regions of the cerebellum in Alzheimer's patients compared to healthy individuals.

CONCLUSION

The findings supported the role of the cerebellum in cognitive functions. Volume reductions may assist clinicians in making an early diagnosis of AD.

Amyloid-β mediates intestinal dysfunction and enteric neurons loss in Alzheimer's disease transgenic mouse

Alzheimer's disease (AD) is traditionally considered as a brain disorder featured by amyloid-β (Aβ) deposition. The current study on whether pathological changes of AD extend to the enteric nervous system (ENS) is still in its infancy. In this study, we found enteric Aβ deposition, intestinal dysfunction, and colonic inflammation in the young APP/PS1 mice. Moreover, these mice exhibited cholinergic and nitrergic signaling pathways damages and enteric neuronal loss. Our data show that Aβ42 treatment remarkably affected the gene expression of cultured myenteric neurons and the spontaneous contraction of intestinal smooth muscles. The intra-colon administration of Aβ42 induced ENS dysfunction, brain gliosis, and β-amyloidosis-like changes in the wild-type mice. Our results suggest that ENS mirrors the neuropathology observed in AD brains, and intestinal pathological changes may represent the prodromal events, which contribute to brain pathology in AD. In summary, our findings provide new opportunities for AD early diagnosis and prevention.

Roles of traditional chinese medicine regulating neuroendocrinology on AD treatment

The incidence of sporadic Alzheimer's disease (AD) is increasing in recent years. Studies have shown that in addition to some genetic abnormalities, the majority of AD patients has a history of long-term exposure to risk factors. Neuroendocrine related risk factors have been proved to be strongly associated with AD. Long-term hormone disorder can have a direct detrimental effect on the brain by producing an AD-like pathology and result in cognitive decline by impairing neuronal metabolism, plasticity and survival. Traditional Chinese Medicine(TCM) may regulate the complex process of endocrine disorders, and improve metabolic abnormalities, as well as the resulting neuroinflammation and oxidative damage through a variety of pathways. TCM has unique therapeutic advantages in treating early intervention of AD-related neuroendocrine disorders and preventing cognitive decline. This paper reviewed the relationship between neuroendocrine and AD as well as the related TCM treatment and its mechanism. The advantages of TCM intervention on endocrine disorders and some pending problems was also discussed, and new insights for TCM treatment of dementia in the future was provided.