Comparative Epidemiological Investigation of Alzheimer's Disease and Colorectal Cancer: The Possible Role of Gastrointestinal Conditions in the Pathogenesis of AD

Mendelian randomization and transcriptomic analysis reveal a positive cause-and-effect relationship between Alzheimer's disease and colorectal cancer

BACKGROUND

This study addresses the complex multifactorial causes of Alzheimer's disease (AD) and colorectal cancer (CRC), two significant public health issues. Despite previous research, the precise relationship between AD and CRC remains unclear. This study aimed to explore the potential causal relationship between AD and CRC using Mendelian randomization (MR) and to identify risk genes through colocalization and transcriptomic analyses.

METHOD

The study used a two-sample Mendelian randomization (MR) approach to investigate the causal effect of AD on CRC. Genome-wide association study (GWAS) summary statistics for AD and CRC were utilized. Colocalization analysis was conducted to identify risk genes associated with AD, which were then validated through transcriptomic analysis in CRC samples. The study used GWAS data from a cohort of European patients and applied several MR methods, including MR Egger, weighted median, and inverse-variance weighted approaches, to ensure robust findings.

RESULTS

The MR analysis revealed a significant positive causal relationship between AD and CRC, indicating that an increased genetic predisposition to AD is associated with a elevated risk of developing CRC. The colocalization analysis identified COLEC11 as a significant risk gene for AD, which also showed a strong positive correlation with clinical features and survival outcomes in CRC. Elevated COLEC11 expression was linked to advanced clinical stages, increased tumor mutational burden, microsatellite instability, and poorer overall survival in CRC patients.

CONCLUSIONS

This study provides evidence of a causal relationship between AD and CRC, suggesting that shared genetic and inflammatory pathways may underlie both conditions. The identification of COLEC11 as a potential link between AD and CRC offers new avenues for research and therapeutic interventions. These findings contribute to a deeper understanding of the interplay between neurodegenerative and oncologic diseases, highlighting the importance of exploring common pathogenic mechanisms.

Slow gut transit increases the risk of Alzheimer's disease: An integrated study of the bi-national cohort in South Korea and Japan and Alzheimer's disease model mice

INTRODUCTION

Although the association between Alzheimer's disease (AD) and constipation is controversial, its causality and underlying mechanisms remain unknown.

OBJECTIVES

To investigate the potential association between slow gut transit and AD using epidemiological data and a murine model.

METHODS

We conducted a bi-national cohort study in South Korea (discovery cohort, N=3,130,193) and Japan (validation cohort, N=4,379,285) during the pre-observation period to determine the previous diagnostic history (2009-2010) and the follow-up period (2011-2021). To evaluate the causality, we induced slow gut transit using loperamide in 5xFAD transgenic mice. Changes in amyloid-beta (Aβ) and other markers were examined using ELISA, qRT-PCR, RNA-seq, and behavioral tests.

RESULTS

Constipation was associated with an increased risk of AD in the discovery cohort (hazard ratio, 2.04; 95% confidence interval [CI], 2.01-2.07) and the validation cohort (hazard ratio; 2.82; 95% CI, 2.61-3.05). We found that loperamide induced slower gut transit in 5xFAD mice, increased Aβ and microglia levels in the brain, increased transcription of genes related to norepinephrine secretion and immune responses, and decreased the transcription of defense against bacteria in the colonic tissue.

CONCLUSION

Impaired gut transit may contribute to AD pathogenesis via the gut-brain axis, thus suggesting a cyclical relationship between intestinal barrier disruption and Aβ accumulation in the brain. We propose that gut transit or motility may be a modifiable lifestyle factor in the prevention of AD, and further clinical investigations are warranted.

Lactiplantibacillus plantarum HEAL9 attenuates cognitive impairment and progression of Alzheimer's disease and related bowel symptoms in SAMP8 mice by modulating microbiota-gut-inflammasome-brain axis

Background: Growing evidence highlights the relevance of the microbiota-gut-brain axis in Alzheimer's disease (AD). AD patients display gut dysbiosis, altered intestinal barrier and enteric inflammation that, besides bowel symptoms, can contribute to brain pathology. In this context, the modulation of gut microbiota is emerging as a therapeutical option to halt or slow down central pathology. Herein, we examined the effects of Lactiplantibacillus plantarum HEAL9 in a spontaneous mouse model of AD. Methods: Senescence-accelerated mouse prone 8 (SAMP8) mice and control SAMR1 mice were treated orally with HEAL9 1 × 109 CFU per mouse per day or placebo for two months to evaluate the effects of the probiotic during the earliest stages of AD, before the development of brain pathology. Cognitive impairment, in vivo and in vitro colonic motility, astrocyte and microglia reactive response, brain and colonic amyloid-β1-42 (Aβ1-42) levels, and inflammasome components activation (NLRP3, ASC, caspase-1 and interleukin-1β) were assessed. In addition, gut barrier alterations [circulating lipopolysaccharide-binding protein (LBP) levels] and acidic mucus were evaluated. Results: HEAL9 administration significantly attenuated cognitive impairment and counteracted colonic dysmotility in SAMP8 mice. Moreover, HEAL9 decreased astrogliosis and microgliosis, Aβ1-42 accumulation and inflammasome activation in colon and brain and normalized plasma LBP levels and colonic acidic mucus content. Conclusion: HEAL9 intake alleviated cognitive decline and normalized colonic motility in the prodromal phases of AD via the modulation of microbiota-gut-inflammasome-brain signalling. Thus, dietary supplementation with HEAL9 could be considered as a suitable therapeutical option for the treatment of AD and related intestinal symptoms in the early stages of the disease.

Oligosaccharides from black ginseng innovatively prepared by low-temperature steam-heating process ameliorate cognitive impairment in Alzheimer's disease mice via the Keap-1/Nrf2 pathway

BACKGROUND

Our objective in this study was to evaluate the effectiveness of oligosaccharides extracted from black ginseng (OSBG), innovatively prepared by a low-temperature steam-heating process, in the improvement of learning and memory impairment in mice, as well as the mechanism(s).

RESULTS

Eight carbohydrates involving isomaltose and maltotetraose were detected in black gensing; monosaccharide residues including mannose and rhamnose were also discovered. OSBG-treated mice showed significant amelioration in recognition and spatial memory deficits compared to the scopolamine group. OSBG could decrease acetylcholinesterase activity in a tissue-dependent fashion but not in a dose-dependent manner. Furthermore, in contrast, OSBG administration resulted in significant upregulation superoxide dismutase, glutathione, glutathione peroxidase (GPx), and Kelch-like ECH-associated protein 1, downregulation of malondialdehyde and nuclear factor erythroid 2-related factor 2 in the tissues. Finally, at the genus level, we observed that the OSBG interventions increased the relative abundance of probiotics (e.g., Barnesiella, Staphylococcus, Clostridium_XlVb) and decreased pernicious bacteria such as Eisenbergiella and Intestinimonas, compared to the Alzheimer's disease mouse model group. Herein, our results demonstrate that OSBG restores the composition of the scopolamine-induced intestinal microbiota in mice, providing homeostasis of gut microbiota and providing evidence for microbiota-regulated therapeutic potential.

CONCLUSION

Our results showed for the first time a clear role for OSBG in improving scopolamine-induced memory impairment by inhibiting cholinergic dysfunction in a tissue-dependent manner. Additionally, OSBG administration relieved oxidative stress by activating the Keap-1/Nrf2 pathway and modulating the gut microbiota. Collectively, OSBG may be a promising target for neuroprotective antioxidants for improving memory and cognition in Alzheimer's disease patients. © 2024 Society of Chemical Industry.

Exploring cognitive trajectories and their association with physical performance: evidence from the China Health and Retirement Longitudinal Study

OBJECTIVES

The long-term trends of cognitive function and its associations with physical performance remain unclear, particularly in Asian populations. The study objectives were to determine cognitive trajectories in middle-aged and elderly Chinese individuals, as well as to examine differences in physical performance across cognitive trajectory groups.

METHODS

Data were extracted from the China Health and Retirement Longitudinal Study. A total of 5,701 participants (47.7% male) with a mean age of 57.8 (standard deviation, 8.4) years at enrollment were included. A group-based trajectory model was used to identify cognitive trajectory groups for each sex. Grip strength, repeated chair stand, and standing balance tests were used to evaluate physical performance. An ordered logistic regression model was employed to analyze differences in physical performance across cognitive trajectory groups.

RESULTS

Three cognitive trajectory groups were identified for each sex: low, middle, and high. For both sexes, higher cognitive trajectory groups exhibited smaller declines with age. In the fully adjusted model, relative to the low trajectory group, the odds ratios (ORs) of better physical performance in the middle cognitive group were 1.37 (95% confidence interval [CI], 1.17 to 1.59; p<0.001) during follow-up and 1.40 (95% CI, 1.20 to 1.64; p<0.001) at the endpoint. The ORs in the high trajectory group were 1.94 (95% CI, 1.61 to 2.32; p<0.001) during follow-up and 2.04 (95% CI, 1.69 to 2.45; p<0.001) at the endpoint.

CONCLUSIONS

Cognitive function was better preserved in male participants and individuals with higher baseline cognitive function. A higher cognitive trajectory was associated with better physical performance over time.

5xFAD mice do not have myenteric amyloidosis, dysregulation of neuromuscular transmission or gastrointestinal dysmotility

BACKGROUND

Alterations in gastrointestinal (GI) function and the gut-brain axis are associated with progression and pathology of Alzheimer's Disease (AD). Studies in AD animal models show that changes in the gut microbiome and inflammatory markers can contribute to AD development in the central nervous system (CNS). Amyloid-beta (Aβ) accumulation is a major AD pathology causing synaptic dysfunction and neuronal death. Current knowledge of the pathophysiology of AD in enteric neurons is limited, and whether Aβ accumulation directly disrupts enteric neuron function is unknown.

METHODS

In 6-month-old 5xFAD (transgenic AD) and wildtype (WT) male and female mice, GI function was assessed by colonic transit in vivo; propulsive motility and GI smooth muscle contractions ex vivo; electrochemical detection of enteric nitric oxide release in vitro, and changes in myenteric neuromuscular transmission using smooth muscle intracellular recordings. Expression of Aβ in the brain and colonic myenteric plexus in these mice was determined by immunohistochemistry staining and ELISA assay.

KEY RESULTS

At 6 months, 5xFAD mice did not show significant changes in GI motility or synaptic neurotransmission in the small intestine or colon. 5xFAD mice, but not WT mice, showed abundant Aβ accumulation in the brain. Aβ accumulation was undetectable in the colonic myenteric plexus of 5xFAD mice.

CONCLUSIONS

5xFAD AD mice are not a robust model to study amyloidosis in the gut as these mice do not mimic myenteric neuronal dysfunction in AD patients with GI dysmotility. An AD animal model with enteric amyloidosis is required for further study.

Impact of constipation on progression of Alzheimer's disease: A retrospective study

BACKGROUND AND PURPOSE

In terms of the gut-brain axis, constipation has been considered to be an important factor of neurodegenerative diseases, although the exact mechanism is still controversial. Herein, we aimed to investigate the contribution of constipation to the progression of dementia in a retrospective study.

METHODS

Patients of Alzheimer's disease(AD) and amnestic mild cognitive impairment were consecutively screened between January 2015 and December 2020, and those of whom brain MRI and neuropsychological tests were performed twice were enrolled in this study. Participants were classified into with constipation (Cons[+], n = 20) and without constipation (Cons[-], n = 64) groups. Laboratory data at the first visit were used. Regression analysis was performed in MMSE, ADAS-Cog, and the volumes of hippocampus on MRI-MPRAGE images and deep white matter lesions (DWMLs) on MRI-FLAIR images obtained at two different time points.

RESULTS

The main finding was that the Cons[+] group showed 2.7 times faster decline in cognitive impairment compared with the Cons[-] group, that is, the liner coefficients of ADAS-Cog were 2.3544 points/year in the Cons[+] and 0.8592 points/year in the Cons[-] groups. Ancillary, changes of DWMLs showed significant correlation with the time span (p < 0.01), and the liner coefficients of DWMLs were 24.48 ml/year in the Cons[+] and 14.83 ml/year in the Cons[-] group, although annual rate of hippocampal atrophy was not different between the two groups. Moreover, serum homocysteine level at baseline was significantly higher in the Cons[+] group than Cons[-] group (14.6 ± 6.4 and 11.5 ± 4.2 nmol/ml, respectively: p = 0.03).

CONCLUSION

There is a significant correlation between constipation and faster progression of AD symptoms along with expansion of DWMLs.

Pathogenic tau recruits wild-type tau into brain inclusions and induces gut degeneration in transgenic SPAM mice

Pathological tau inclusions are neuropathologic hallmarks of many neurodegenerative diseases. We generated and characterized a transgenic mouse model expressing pathogenic human tau with S320F and P301S aggregating mutations (SPAM) at transgene levels below endogenous mouse tau protein levels. This mouse model develops a predictable temporal progression of tau pathology in the brain with biochemical and ultrastructural properties akin to authentic tau inclusions. Surprisingly, pathogenic human tau extensively recruited endogenous mouse tau into insoluble aggregates. Despite the early onset and rapid progressive nature of tau pathology, major neuroinflammatory and transcriptional changes were only detectable at later time points. Moreover, tau SPAM mice are the first model to develop loss of enteric neurons due to tau accumulation resulting in a lethal phenotype. With moderate transgene expression, rapidly progressing tau pathology, and a highly predictable lethal phenotype, the tau SPAM model reveals new associations of tau neurotoxicity in the brain and intestinal tract.

Prevalence of Constipation in Elderly and Its Association With Dementia and Mild Cognitive Impairment: A Cross-Sectional Study

Background

Constipation and dementia have similar epidemiological characteristics. Changes in intestinal flora and characteristics of the brain-gut axis play roles in the pathogeneses of the two diseases, suggesting that there may be a close connection between the two. Most of the studies on constipation in dementia patients have focused on the population with α-synucleinopathies [Parkinson’s disease dementia (PDD), dementia with Lewy bodies (DLB)]. Few studies have reported the prevalence of constipation in all-cause dementia and mild cognitive impairment (MCI) populations.

Objective

To assess the prevalence of constipation in patients with all-cause dementia and MCI subtypes and to explore the association between constipation with dementia and MCI subtypes.

Methods

From May 2019 to December 2019, we conducted a population-based cross-sectional survey. A total of 11,743 participants aged 65 or older from nine cities in China were surveyed. Participants underwent a series of clinical examinations and neuropsychological measurements. Constipation, dementia, MCI and MCI subtype were diagnosed according to established criteria through standard diagnostic procedures.

Results

The overall age- and sex-adjusted prevalence of constipation in individuals aged 65 years and older was 14.8% (95% CI, 14.6–15.0). The prevalence rates of constipation were19.2% (95% CI, 17.3–21.0), 19.1% (95% CI, 16.8–21.5), 14.4% (95% CI, 12.8–15.9), and 13.8% (95% CI, 13.0–14.6) in the dementia, non-amnestic (na)-MCI, amnestic (a)-MCI and normal cognition populations, respectively. Multivariate logistic regression analysis showed that higher prevalence of constipation was associated with dementia (p = 0.0.032, OR = 1.18, 95% CI: 1.02–1.38) and na-MCI (p = 0.003, OR = 1.30, 95% CI: 1.09–1.54).

Conclusion

The present study found a high prevalence of constipation in elderly individuals in China, and higher in patients with dementia and na-MCI.

MicroRNA-Target Interaction Regulatory Network in Alzheimer's Disease

Alzheimer’s Disease (AD) is a progressive neurodegenerative disorder and the most common cause of dementia; however, early diagnosis of the disease is challenging. Research suggests that biomarkers found in blood, such as microRNAs (miRNA), may be promising for AD diagnostics. Experimental data on miRNA–target interactions (MTI) associated with AD are scattered across databases and publications, thus making the identification of promising miRNA biomarkers for AD difficult. In response to this, a list of experimentally validated AD-associated MTIs was obtained from miRTarBase. Cytoscape was used to create a visual MTI network. STRING software was used for protein–protein interaction analysis and mirPath was used for pathway enrichment analysis. Several targets regulated by multiple miRNAs were identified, including: BACE1, APP, NCSTN, SP1, SIRT1, and PTEN. The miRNA with the highest numbers of interactions in the network were: miR-9, miR-16, miR-34a, miR-106a, miR-107, miR-125b, miR-146, and miR-181c. The analysis revealed seven subnetworks, representing disease modules which have a potential for further biomarker development. The obtained MTI network is not yet complete, and additional studies are needed for the comprehensive understanding of the AD-associated miRNA targetome.

Spermine protects aluminium chloride and iron-induced neurotoxicity in rat model of Alzheimer's disease via attenuation of tau phosphorylation, Amyloid-β (1-42) and NF-κB pathway

Alzheimer's disease (AD) is the most prevalent type of dementia, characterized by a gradual decline in cognitive and memory functions of the aged peoples. Long-term exposure to heavy metals (aluminium and iron) cause neurotoxicity by amyloid plaques accumulation, tau phosphorylation, increased oxidative stress, neuroinflammation, and cholinergic neurons degeneration, contributes to the development of AD-like symptoms. The present research work is designed to investigate the neuroprotective effect of spermine in aluminium chloride (AlCl₃), and iron (Fe) induced AD-like symptoms in rats. Rats were administered of AlCl₃ (100 mg/kg p.o.) alone and in combination with iron (120 μg/g, p.o.) for 28 days. Spermine (5 and 10 mg/kg) through intraperitoneal (i.p.) route was given for 14 days. The recognition and spatial memory impairment were tasted using Morris water maze (MWM), actophotometer, and Novel Object Recognition test (NORT). All the rats were sacrificed on day 29, brains were isolated, and tissue homogenate was used for neuroinflammatory, biochemical, neurotransmitters, metals concentration, and nuclear factor-kappa B (NF-κB) analysis. In the present study, AlCl₃ and iron administration elevated oxidative stress, cytokines release, dysbalanced neurotransmitters concentration, and biochemical changes. Rats treated with spermine dose-dependently improved the recognition and spatial memory, attenuated proinflammatory cytokine release, and restored neurotransmitters concentration and antioxidant enzymes. Spermine also mitigated the increased beta-amyloid (Aβ42), with downregulation of tau phosphorylation. Furthermore, spermine augmented the hippocampal levels of B cell leukaemia/lymphoma-2 (Bcl-2), diminished nuclear factor-kappa B (NF-κB) and caspase-3 (casp-3) expression. Moreover, spermine exhibited the neuroprotective effect through anti-inflammatory, antioxidant, neurotransmitters restoration, anti-apoptotic Aβ42 concentration.

Chronic colitis exacerbates NLRP3-dependent neuroinflammation and cognitive impairment in middle-aged brain

BACKGROUND

Neuroinflammation is a major driver of age-related brain degeneration and concomitant functional impairment. In patients with Alzheimer's disease, the most common form of age-related dementia, factors that enhance neuroinflammation may exacerbate disease progression, in part by impairing the glymphatic system responsible for clearance of pathogenic beta-amyloid. Inflammatory bowel diseases (IBDs) induce neuroinflammation and exacerbate cognitive impairment in the elderly. The NACHT-LRR and pyrin (PYD) domain-containing protein 3 (NLRP3) inflammasome has been implicated in neuroinflammation. Therefore, we examined if the NLRP3 inflammasome contributes to glymphatic dysfunction and cognitive impairment in an aging mouse model of IBD.

METHODS

Sixteen-month-old C57BL/6J and NLRP3 knockout (KO) mice received 1% wt/vol dextran sodium sulfate (DSS) in drinking water to model IBD. Colitis induction was confirmed by histopathology. Exploratory behavior was examined in the open field, associative memory by the novel-object recognition and Morris water maze tests, glymphatic clearance by in vivo two-photon imaging, and neuroinflammation by immunofluorescence and western blotting detection of inflammatory markers.

RESULTS

Administration of DSS induced colitis, impaired spatial and recognition memory, activated microglia, and increased A1-like astrocyte numbers. In addition, DSS treatment impaired glymphatic clearance, aggravated amyloid plaque accumulation, and induced neuronal loss in the cortex and hippocampus. These neurodegenerative responses were associated with increased NLRP3 inflammasome expression and accumulation of gut-derived T lymphocytes along meningeal lymphatic vessels. Conversely, NLRP3 depletion protected against cognitive dysfunction, neuroinflammation, and neurological damage induced by DSS.

CONCLUSIONS

Colitis can exacerbate age-related neuropathology, while suppression of NLRP3 inflammasome activity may protect against these deleterious effects of colitis.

The pleiotropic neuroprotective effects of resveratrol in cognitive decline and Alzheimer's disease pathology: From antioxidant to epigenetic therapy

While the elderly segment of the population continues growing in importance, neurodegenerative diseases increase exponentially. Lifestyle factors such as nutrition, exercise, and education, among others, influence ageing progression, throughout life. Notably, the Central Nervous System (CNS) can benefit from nutritional strategies and dietary interventions that prevent signs of senescence, such as cognitive decline or neurodegenerative diseases such as Alzheimer's disease and Parkinson's Disease. The dietary polyphenol Resveratrol (RV) possesses antioxidant and cytoprotective effects, producing neuroprotection in several organisms. The oxidative stress (OS) occurs because of Reactive oxygen species (ROS) accumulation that has been proposed to explain the cause of the ageing. One of the most harmful effects of ROS in the cell is DNA damage. Nevertheless, there is also evidence demonstrating that OS can produce other molecular changes such as mitochondrial dysfunction, inflammation, apoptosis, and epigenetic modifications, among others. Interestingly, the dietary polyphenol RV is a potent antioxidant and possesses pleiotropic actions, exerting its activity through various molecular pathways. In addition, recent evidence has shown that RV mediates epigenetic changes involved in ageing and the function of the CNS that persists across generations. Furthermore, it has been demonstrated that RV interacts with gut microbiota, showing modifications in bacterial composition associated with beneficial effects. In this review, we give a comprehensive overview of the main mechanisms of action of RV in different experimental models, including clinical trials and discuss how the interconnection of these molecular events could explain the neuroprotective effects induced by RV.

Constipation and Its Associated Factors among Patients with Dementia

Constipation is one of the most frequent non-motor problems in older adults. As constipation is commonly ignored by dementia patients, it is not usually reported on time. Constipation has a serious impact on the activity of daily living and quality of life in dementia patients. The relationships between constipation, demographic variables, and the nutritional status of patients with dementia remain unknown. This study aimed to assess the possible factors associated with constipation. This cross-sectional study was conducted at the Kaohsiung Chang Gung Memorial Hospital from January to November 2019. This hospital is a medical center and the main referral hospital of southern Taiwan, serving 3 million inhabitants. In total, 119 patients with dementia were evaluated using the Rome III diagnostic criteria for functional constipation. There were 30 patients with dementia included in the constipation group and 89 patients with dementia included in the no constipation group. Mini-Nutritional Assessment and 3-day diet diary records were employed. The clinical dementia rating score was used to evaluate the severity of dementia in patients of the outpatient clinic. Approximately 25.2% of dementia patients had constipation. Patients in the dementia with constipation group were older, had severer dementia, and displayed a lower water intake. After multivariable adjustment, low liquid consumption was the predictor of constipation among patients with dementia. The findings support the clinical recommendations to treat constipation with an increased liquid intake, but not exercise, in dementia patients.

Cause of death among patients with colorectal cancer: a population-based study in the United States

CRC (Colorectal cancer) is one of the most common causes of death worldwide and in the US (United States). In this study, we aim to perform a population-based analysis on the cause of death among patients with CRC in the US. A total of 834,510 CRC patients diagnosed between 1975 and 2016 in the US were selected from the SEER (Surveillance, Epidemiology, and End Results) program. Causes of death among CRC patients were characterized and SMRs (standardized mortality ratios) of death from non-cancer causes were calculated. Among all CRC patients included in this study, a total of 531,507 deaths were recorded, of which 51.3% were due to CRC, 10.3% were due to other cancers, and 38.4% were due to non-cancer causes. Recently, there has been a relative decrease in index-cancer deaths and an increase in non-cancer causes among CRC patients. The mortality risk from non-cancer rises with accumulating age and longer follow-up time. Cardiovascular diseases are the most prevalent non-cancer causes, accounting for 20.3% of all deaths among CRC patients. Compared with the general population, the mortality rate of non-cancer deaths among CRC patients is doubled (SMR, 2.02; 95% confidence interval, 2.01-2.03).

Discovery of Gut Bacteria Specific to Alzheimer's Associated Diseases is a Clue to Understanding Disease Etiology: Meta-Analysis of Population-Based Data on Human Gut Metagenomics and Metabolomics

Alzheimer's disease (AD)-associated sequence (ADAS) of cultured fecal bacteria was discovered in human gut targeted screening. This study provides important information to expand our current understanding of the structure/activity relationship of ADAS and putative inhibitors/activators that are potentially involved in ADAS appearance/disappearance. The NCBI database analysis revealed that ADAS presents at a large proportion in American Indian Oklahoman (C&A) with a high prevalence of obesity/diabetes and in colorectal cancer (CRC) patients from the US and China. An Oklahoman non-native group (NNI) showed no ADAS. Comparison of two large US populations reveals that ADAS is more frequent in individuals aged ≥66 and in females. Prevalence and levels of fecal metabolites are altered in the C&A and CRC groups versus controls. Biogenic amines (histamine, tryptamine, tyramine, phenylethylamine, cadaverine, putrescine, agmatine, spermidine) that present in food and are produced by gut microbiota are significantly higher in C&A (e.g., histamine/histidine 95-fold) versus NNI (histamine/histidine 16-fold). The majority of these bio-amines are cytotoxic at concentrations found in food. Inositol phosphate signaling implicated in AD is altered in C&A and CRC. Tryptamine stimulated accumulation of inositol phosphate. The seizure-eliciting tryptamine induced cytoplasmic vacuolization and vesiculation with cell fragmentation. Present additions of ADAS-carriers at different ages including infants led to an ADAS-comprising human sample size of 2,830 from 27 studies from four continents (North America, Australia, Asia, Europe). Levels of food-derived monoamine oxidase inhibitors and anti-bacterial compounds, the potential modulators of ADAS-bacteria growth and biogenic amine production, were altered in C&A versus NNI. ADAS is attributable to potentially modifiable risk factors of AD associated diseases.

Maillard Reaction Products and Phenolic Compounds from Roasted Peanut Flour Extracts Prevent Scopolamine-Induced Amnesia Via Cholinergic Modulation and Antioxidative Effects in Mice

Research on the beneficial effects of Maillard reaction products (MRPs) and phenolic compounds derived from roasted peanut flour on the nervous system remains insufficient. This study aimed to evaluate the effect of a 28-day oral administration of defatted peanut extract rich in MPRs and polyphenolic compounds on the cognitive impairments and oxidative injury induced by scopolamine in a mouse model. Light and dark extracts from peanut flour were prepared by heating peanuts at 187°C for two different times (8.6 and 12.7 min) and defatted using soxhlet apparatus. The mice were orally pretreated with either roasted defatted peanuts extracts (100 mg/kg) or donepezil (3 mg/kg) for 21 days. On day 19 and until day 28, mice were injected subcutaneously with water or scopolamine (1 mg/kg body weight) 15 min after roasted defatted peanuts extracts/water feeding. Mice were subsequently subjected to a battery of behavioral tests including open field locomotor activity assay, and Morris water maze test. Brain tissues were collected to measure acetylcholine, acetylcholinesterase, and oxidative parameters (glutathione and malondialdehyde). Roasted defatted peanuts (light and dark) (100 mg/kg) treatment significantly ameliorated cognitive performance and reversed the oxidative damage when compared with the scopolamine group. These data demonstrate the defatted peanuts extracts exert potent anti-amnesic effects via the modulation of cholinergic and antioxidant activities.

Inactive bowel movement and stroke are associated with increased risks of mild cognitive impairment among community-living Singapore elderly

Mild cognitive impairment (MCI), as a preclinical phase of dementia, provides an invaluable time window for intervention. Besides several proposed modifiable risk factors, the associations of MCI with dietary habits and bowel movement are not well clarified. We thus conducted a cross-sectional study of community-living Singapore elderly and focused on the relationship of clinically diagnosed MCI with dietary habits and bowel movement frequencies. The multiple logistic regression results showed that frequent (≥4 days per week) fruit consumption (P = 0.004), active (≥4 days per week) bowel movement within 10 minutes (P = 0.027), and years of schooling were negatively associated with MCI occurrence. In contrast, medical comorbidities including hypertension, stroke, and cataract/glaucoma were found to be risk factors. Furthermore, a Bayesian network model of causal inference detected five hypothesized causal-association paths leading to MCI, namely bowel movement, stroke, years of schooling via fruit consumption, hypertension via stroke and hypertension via cataract/glaucoma. The combination of the two direct factors (inactive bowel movement and stroke) reached a maximum conditional probability of 60.00% for MCI occurrence. Taken together, this study was the first to link bowel movement with MCI occurrence. In addition, it suggested five modifiable hypothesized causal-association paths to MCI.

Current insights on lipid nanocarrier-assisted drug delivery in the treatment of neurodegenerative diseases

The central nervous system (CNS) is vulnerable to pathologic processes that lead to the development of neurodegenerative disorders like Alzheimer's, Parkinson's and Huntington's diseases, Multiple sclerosis or Amyotrophic lateral sclerosis. These are chronic and progressive pathologies characterized by the loss of neurons and the formation of misfolded proteins. Additionally, neurodegenerative diseases are accompanied by a structural and functional dysfunction of the blood-brain barrier (BBB). Although serving as a protection for the CNS, the existence of physiological barriers, especially the BBB, limits the access of several therapeutic agents to the brain, constituting a major hindrance in neurotherapeutics advancement. In this regard, nanotechnology-based approaches have arisen as a promising strategy to not only improve drug targeting to the brain, but also to increase bioavailability. Lipid nanocarriers such as liposomes, solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), microemulsions and nanoemulsions, have already proven their potential for enhancing brain transport, crossing more easily into the CNS and allowing the administration of medicines that could benefit the treatment of neurological pathologies. Given the socioeconomic impact of such conditions and the advent of nanotechnology that inevitably leads to more effective and superior therapeutics for their management, it is imperative to constantly update on the current knowledge of these topics. Herein, we provide insight on the BBB and the pathophysiology of the main neurodegenerative disorders. Moreover, this review seeks to highlight the several approaches that can be used to improve the delivery of therapeutic agents to the CNS, while also offering an extensive overview of the latest efforts regarding the use of lipid-based nanocarriers in the management of neurodegenerative diseases.

Recent Advancements in Pathogenesis, Diagnostics and Treatment of Alzheimer's Disease

BACKGROUND

The only conclusive way to diagnose Alzheimer's is to carry out brain autopsy of the patient's brain tissue and ascertain whether the subject had Alzheimer's or any other form of dementia. However, due to the non-feasibility of such methods, to diagnose and conclude the conditions, medical practitioners use tests that examine a patient's mental ability.

OBJECTIVE

Accurate diagnosis at an early stage is the need of the hour for initiation of therapy. The cause for most Alzheimer's cases still remains unknown except where genetic distinctions have been observed. Thus, a standard drug regimen ensues in every Alzheimer's patient, irrespective of the cause, which may not always be beneficial in halting or reversing the disease progression. To provide a better life to such patients by suppressing existing symptoms, early diagnosis, curative therapy, site-specific delivery of drugs, and application of hyphenated methods like artificial intelligence need to be brought into the main field of Alzheimer's therapeutics.

METHODS

In this review, we have compiled existing hypotheses to explain the cause of the disease, and highlighted gene therapy, immunotherapy, peptidomimetics, metal chelators, probiotics and quantum dots as advancements in the existing strategies to manage Alzheimer's.

CONCLUSION

Biomarkers, brain-imaging, and theranostics, along with artificial intelligence, are understood to be the future of the management of Alzheimer's.

The analysis of miRNA expression profiling datasets reveals inverse microRNA patterns in glioblastoma and Alzheimer's disease

There is recent evidence to indicate the existence of an inverse association between the incidence of neurological disorders and cancer development. Concurrently, the transcriptional pathways responsible for the onset of glioblastoma multiforme (GBM) and Alzheimer's disease (AD) have been found to be mutually exclusive between the two pathologies. Despite advancements being made concerning the knowledge of the molecular mechanisms responsible for the development of GBM and AD, little is known about the identity of the microRNA (miRNAs or miRs) involved in the development and progression of these two pathologies and their possible inverse expression patterns. On these bases, the aim of the present study was to identify a set of miRNAs significantly de-regulated in both GBM and AD, and hence to determine whether the identified miRNAs exhibit an inverse association within the two pathologies. For this purpose, miRNA expression profiling datasets derived from the Gene Expression Omnibus (GEO) DataSets and relative to GBM and AD were used. Once the miRNAs significantly de-regulated in both pathologies were identified, DIANA-mirPath pathway prediction and STRING Gene Ontology enrichment analyses were performed to establish their functional roles in each of the pathologies. The results allowed the identification of a set of miRNAs found de-regulated in both GBM and AD, whose expression levels were inversely associated in the two pathologies. In particular, a strong negative association was observed between the expression levels of miRNAs in GBM compared to AD, suggesting that although the molecular pathways behind the development of these two pathologies are the same, they appear to be inversely regulated by miRNAs. Despite the identification of this set of miRNAs which may be used for diagnostic, prognostic and therapeutic purposes, further functional in vitro and in vivo evaluations are warranted in order to validate the diagnostic and therapeutic potential of the identified miRNAs, as well as their involvement in the development of GBM and AD.

The Gut-Brain Axis in Neurodegenerative Diseases and Relevance of the Canine Model: A Review

Identifying appropriate animal models is critical in developing translatable in vitro and in vivo systems for therapeutic drug development and investigating disease pathophysiology. These animal models should have direct biological and translational relevance to the underlying disease they are supposed to mimic. Aging dogs not only naturally develop a cognitive decline in many aspects including learning and memory deficits, but they also exhibit human-like individual variability in the aging process. Neurodegenerative processes that can be observed in both human and canine brains include the progressive accumulation of β-amyloid (Aβ) found as diffuse plaques in the prefrontal cortex (PFC), including the gyrus proreus (i.e., medial orbital PFC), as well as the hippocampus and the cerebral vasculature. Tau pathology, a marker of neurodegeneration and dementia progression, was also found in canine hippocampal synapses. Various epidemiological data show that human patients with neurodegenerative diseases have concurrent intestinal lesions, and histopathological changes in the gastrointestinal (GI) tract occurs decades before neurodegenerative changes. Gut microbiome alterations have also been reported in many neurodegenerative diseases including Alzheimer's (AD) and Parkinson's diseases, as well as inflammatory central nervous system (CNS) diseases. Interestingly, the dog gut microbiome more closely resembles human gut microbiome in composition and functional overlap compared to rodent models. This article reviews the physiology of the gut-brain axis (GBA) and its involvement with neurodegenerative diseases in humans. Additionally, we outline the advantages and weaknesses of current in vitro and in vivo models and discuss future research directions investigating major human neurodegenerative diseases such as AD and Parkinson's diseases using dogs.