Western diet as a trigger of Alzheimer's disease: From metabolic syndrome and systemic inflammation to neuroinflammation and neurodegeneration

High fat diet induces differential age- and gender-dependent changes in neuronal function in Drosophila linked to redox stress

The prevalence of neurodegenerative diseases, such as Alzheimer's and Parkinson's disease, is steadily increasing, thus posing significant challenges to global healthcare systems. Emerging evidence suggests that dietary habits, particularly consumption of high-fat diets, may play a pivotal role in the development and progression of neurodegenerative disorders. Moreover, several studies have shed light on the intricate communication between the gut and the brain, linking gut health with neuroinflammation and its involvement in neurodegenerative processes. This study aims to assess the effects of a high-fat dietary intake on various aspects of neuronal function during aging in a gender specific manner to help understand the potential contributions of diet to neuronal function. To investigate the effects of a high-fat diet, Drosophila melanogaster was used and exposed to a standard normal food diet (NF) and a high-fat diet (HF). Adults were grouped at 10 and 45 days of age in male and female flies reared under the same conditions starting the HF diet at 5 days of age with data showing differential gender- and HF diet-induced phenotypes. Malondialdehyde (MDA) levels were higher in males at 10 and 45 days (p < 0.05), caspase-3 expression increased at 45 days (p < 0.01) implicating apoptosis induction and a reduced climbing activity at 10 and 45 days was apparent in females only (p < 0.01). Adult lifespan under both dietary conditions was unchanged when reared at 18°C but odour-associated learning ability was reduced in larvae reared in a HF diet throughout their development (p < 0.05). This is the first study to characterise effects of a HF diet on neuronal phenotypes in an age- and gender-specific manner in a Drosophila model. Our findings suggest a HF diet induces differential effects of neuronal dysfunction with age and sex-specific outcomes, characterised by enhanced oxidative stress and cell death impacting on behaviour.

Role of Pyroptosis in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a serious chronic condition marked by persistent and recurrent intestinal ulcers. Although the exact cause of IBD remains unclear, it is generally accepted that a complex interaction among dietary factors, gut microbiota, and immune responses in genetically predisposed individuals contributes to its development. Pyroptosis, an inflammatory form of programmed cell death activated by inflammasomes, is marked by the rupture of cell membranes and the subsequent release of inflammatory mediators. Emerging evidence indicates that pyroptosis plays a crucial role in the pathogenesis of IBD. Moderate pyroptosis activation can enhance intestinal immune defenses, while excessive inflammasome activation can trigger an inflammatory cascade, resulting in increased damage to intestinal tissues. This article reviews the molecular mechanisms underlying pyroptosis and highlights its role in the onset and progression of IBD. Furthermore, We explore recent advancements in IBD treatment, focusing on small molecule compounds that specifically target and inhibit pyroptosis.

Traumatic brain injury from a peripheral axis perspective: Uncovering the roles of liver and adipose tissue in temperature regulation

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Most current treatments for TBI and other neurological disorders focus on the brain, often overlooking the significant contributions of peripheral organs to disease progression. Emerging evidence suggests that organs such as the liver and adipose tissue play crucial roles in TBI pathogenesis. The liver synthesizes lipids and proteins vital for brain function, while adipose tissue provides hormones and metabolites that influence brain activity. New research indicates that the liver and adipose tissue work in concert with the hypothalamus to regulate essential processes, such as body temperature, which become disrupted in TBI. Additionally, the brain-peripheral axis-a complex network of visceral nerve pathways, hormones, and metabolites-plays a bidirectional role in regulating brain plasticity and function. Understanding how TBI leads to dysregulation of the liver, adipose tissue, and other organs could unlock new therapeutic opportunities for treating TBI and related neurological disorders. The intricate autonomic network involving hypothalamic and enteric neurons, along with visceral nerve pathways and hormones, presents both pathological targets and therapeutic potential. We examine scientific evidence suggesting that correcting disturbances in systemic physiology could enhance the brain's capacity for healing. However, the interdependence of this autonomic network implies that treating dysfunction in one area may affect others. Therefore, we also explore the mechanisms by which diet and exercise can comprehensively impact the brain-peripheral axis, supporting the healing process. CHEMICAL COMPOUNDS: D-Fructose (PubChem CID 2723872); docosahexaenoic acid (PubChem CID 45934466); eicosapentaenoic acid (PubChem 5282847).

Acarbose ameliorates Western diet-induced metabolic and cognitive impairments in the 3xTg mouse model of Alzheimer's disease

Age is the greatest risk factor for Alzheimer's disease (AD) as well as for other disorders that increase the risk of AD such as diabetes and obesity. There is growing interest in determining if interventions that promote metabolic health can prevent or delay AD. Acarbose is an anti-diabetic drug that not only improves glucose homeostasis, but also extends the lifespan of wild-type mice. Here, we test the hypothesis that acarbose will not only preserve metabolic health, but also slow or prevent AD pathology and cognitive deficits in 3xTg mice, a model of AD, fed either a Control diet or a high-fat, high-sucrose Western diet (WD). We find that acarbose decreases the body weight and adiposity of WD-fed 3xTg mice, increasing energy expenditure while also stimulating food consumption, and improves glycemic control. Both male and female WD-fed 3xTg mice have worsened cognitive deficits than Control-fed mice, and these deficits are ameliorated by acarbose treatment. Molecular and histological analysis of tau and amyloid pathology identified sex-specific effects of acarbose which are uncoupled from the dramatic improvements in cognition in females, suggesting that the benefits of acarbose on AD may be largely driven by improved metabolic health. In conclusion, our results suggest that acarbose may be a promising intervention to prevent, delay, or even treat AD, especially in individuals consuming a WD.

A Mediterranean-style diet protects against cognitive and behavioral deficits, adiposity, and Alzheimer's disease-related markers, compared to a macronutrient-matched typical American diet in C57BL/6J mice

BackgroundResearch suggests that modifying risk factors may prevent or delay up to 40% of dementia cases, including Alzheimer's disease (AD). Thus, understanding the potential of healthful dietary patterns, like the Mediterranean diet (MD), in AD prevention is crucial. While supplementation of individual Mediterranean foods has demonstrated efficacy in reducing AD biomarkers and cognitive impairment in rodents, the effects of a comprehensive MD warrant further investigation. Additionally, while rodent studies often use a "Western diet" as a model for the typical American diet (TAD), these diets generally exceed the macronutrient densities of typical American consumption, particularly in fats and carbohydrates.ObjectiveTo better reflect human diets, we developed two diets for mice that more closely mirrored the macronutrient composition of the traditional MD or the TAD, each with matched macronutrient profiles (50% kcal from carbohydrates, 35% kcal from fat, 15% kcal from protein), and distinct food sources from Mediterranean regions or the U.S., respectively.MethodsMale C57BL/6J mice were randomly assigned to one diet (MD or TAD) at weaning (21 days of age), which they consumed for six months.ResultsCompared to the TAD, MD animals had lower body weight, abdominal and hepatic fat, serum TNF-α, and central Aβ1-42, while also exhibiting enhanced exploratory behavior, reduced anxiety-like behavior, and preserved spatial memory. The MD also protected against LPS-induced central inflammation and BDNF loss.ConclusionsThese findings suggest that a comprehensive MD provides protection against metabolic and AD-related markers in wildtype mice, despite matched caloric availability to the TAD.

Ultraprocessed Foods and Neuropsychiatric Outcomes: Putative Mechanisms

A body of evidence indicates an association between ultraprocessed foods (UPFs) and health outcomes. Most of it has been obtained through preclinical studies, although a number of observational studies substantiate how a high intake of these products increases the risk of neuropsychiatric disorders, and an increasing amount of dietary intervention studies confirm these findings. The aim of this narrative review is to describe some of the putative mechanisms involved in the deleterious effects of a high intake of UPFs on neuropsychiatric outcomes. A myriad of unhealthy actions may be associated with the consumption of UPFs, and some mechanisms are being discussed. They include UPFs' high caloric density; their high sugar, sodium, and additives content and low amounts of fiber; and a high palatability that induces overconsumption, acting as obesogens. Moreover, thermal treatment of these foods generates oxidative products such as glycotoxins, lipotoxins, and acrolein, all of which affect the brain. The chemical products act, directly or indirectly, on the gut microbiome and affect the gut-brain axis, causing neuroinflammation, oxidative stress, and neurodegeneration. UPFs also exert various epigenetic effects that affect mental health and might explain the intergenerational inheritance of neuropsychiatric disorders. A diet containing a high proportion of these foods has a low nutritional density, including bioactive protective agents such as antioxidant and anti-inflammatory compounds that promote eubiosis. The evidence shows that UPFs intake affects neuropsychiatric outcomes such as neurodegeneration, cognitive decline, dementia, and mood disorders and reinforces the need to promote a healthy dietary pattern throughout all life stages, thus interfering with the current commercial determinants of health.

Mitophagy in Alzheimer's disease and other metabolic disorders: A focus on mitochondrial-targeted therapeutics

Mitochondria, as central regulators of cellular processes such as energy production, apoptosis, and metabolic homeostasis, are essential to cellular function and health. The maintenance of mitochondrial integrity, especially through mitophagy-the selective removal of impaired mitochondria-is crucial for cellular homeostasis. Dysregulation of mitochondrial function, dynamics, and biogenesis is linked to neurodegenerative and metabolic diseases, notably Alzheimer's disease (AD), which is increasingly recognized as a metabolic disorder due to its shared pathophysiologic features: insulin resistance, oxidative stress, and chronic inflammation. In this review, we highlight recent advancements in pharmacological interventions, focusing on agents that modulate mitophagy, mitochondrial uncouplers that reduce oxidative phosphorylation, compounds that directly scavenge reactive oxygen species to alleviate oxidative stress, and molecules that ameliorate amyloid beta plaque accumulation and phosphorylated tau pathology. Additionally, we explore dietary and lifestyle interventions-MIND and ketogenic diets, caloric restriction, physical activity, hormone modulation, and stress management-that complement pharmacological approaches and support mitochondrial health. Our review underscores mitochondria's central role in the pathogenesis and potential treatment of neurodegenerative and metabolic diseases, particularly AD. By advocating for an integrated therapeutic model that combines pharmacological and lifestyle interventions, we propose a comprehensive approach aimed at mitigating mitochondrial dysfunction and improving clinical outcomes in these complex, interrelated diseases.

Exploring the association between urticaria subtypes, anxiety, and depression and potential role of gut microbiota

AIMS

In observational studies, the causal relationship between urticaria and the risk of psychiatric disorders (anxiety and depression) remains inconclusive. Furthermore, there is growing evidence that gut microbiota (GM) contributes to the pathogenesis of urticaria. This study aimed to assess the causal relationships between the genetically predicted urticaria subtypes and psychiatric disorders and further examined the role of GM in influencing the risk of these urticaria subtypes.

METHODS

We conducted a meta-analysis of observational studies identified from four databases to evaluate the associations between urticaria, anxiety, and depression over the past decade. In addition, we estimated the genetic correlation and causality between genetically predicted urticaria subtypes and psychiatric disorders using linkage disequilibrium score regression and Mendelian Randomization (MR) analyses. Finally, univariable two-sample MR and multivariable MR analyses were employed to evaluate the combined and independent effects of GM from two datasets on urticaria subtypes associated with psychiatric disorders.

RESULTS

Thirteen observational studies comprising 7321 participants were included in the meta-analysis. There was a positive association between urticaria and anxiety risk (n = 13, OR: 3.96; 95%CI: 2.90-5.41) as well as depression risk (n = 12, OR: 3.03; 95%CI: 2.30-4.01). The MR results indicated that idiopathic urticaria increased the risk of anxiety (OR = 1.14; 95%CI = 1.01-1.28; P = 3.31 × 10-2), while allergic urticaria increased the risk of major depressive disorder (OR = 1.07; 95%CI = 1.02-1.13; P = 6.65 × 10-3). Our analysis identified nineteen gut bacterial taxa that were causally associated with idiopathic and allergic urticaria. Notably, Intestinibacter and Victivallales were strongly associated with an increased risk of allergic urticaria, even after accounting for the effect of smoking or alcohol consumption in the multivariable MR analysis. FamilyXIIIAD3011group and Bacteroides vulgatus were found to exert protective roles in idiopathic urticaria.

CONCLUSIONS

The study provides evidence for the association between urticaria subtypes and psychiatric disorders, complementing existing observational studies. In addition, our study implies the involvement of gut microbiota in idiopathic and allergic urticaria. However, the specific mechanisms of bacterial action remain to be clarified.

Taking flight, the use of Drosophila melanogaster for neuroscience research in Uruguay

The Sociedad de Neurociencias del Uruguay is celebrating its 30th anniversary, sustained by more than a century of neuroscience research in the country. During this time, different approaches and experimental organisms have been incorporated to study diverse aspects of neurobiology. One of these experimental animals, successfully used in a variety of biological fields, is the fruit fly Drosophila melanogaster. Although Drosophila has been a model organism for neuroscience research worldwide for many decades, its use in Uruguay for that purpose is relatively new and just taking flight. In this special issue article, we will describe some of the research lines that are currently using Drosophila for neuroscience studies, questioning a wide range of issues including thermoreception, neurodegenerative diseases such as Parkinson's, screening of bioactive compounds with a neuroprotective effect, and gene/protein function during development of the nervous system. The consolidation of these research lines has been achieved due to unique features of D. melanogaster as an experimental model. We will review the advantages of using Drosophila to study neurobiology and describe some of its useful genetic tools. Advantages such as having powerful genetics, highly conserved disease pathways, a complete connectome, very low comparative costs, easy maintenance, and the support of a collaborative community allowing access to a vast toolkit, all make D. melanogaster an ideal model organism for neuroscientists in countries with low levels of investment in research and development. This review focuses on the strengths and description of useful techniques to study neurobiology using Drosophila, from the perspective of a Latin-American experience.

Intermittent fasting and neurodegenerative diseases: Molecular mechanisms and therapeutic potential

Neurodegenerative disorders are straining public health worldwide. During neurodegenerative disease progression, aberrant neuronal network activity, bioenergetic impairment, adaptive neural plasticity impairment, dysregulation of neuronal Ca2+ homeostasis, oxidative stress, and immune inflammation manifest as characteristic pathological changes in the cellular milieu of the brain. There is no drug for the treatment of neurodegenerative disorders, and therefore, strategies/treatments for the prevention or treatment of neurodegenerative disorders are urgently needed. Intermittent fasting (IF) is characterized as an eating pattern that alternates between periods of fasting and eating, requiring fasting durations that vary depending on the specific protocol implemented. During IF, depletion of liver glycogen stores leads to the production of ketone bodies from fatty acids derived from adipocytes, thereby inducing an altered metabolic state accompanied by cellular and molecular adaptive responses within neural networks in the brain. At the cellular level, adaptive responses can promote the generation of synapses and neurons. At the molecular level, IF triggers the activation of associated transcription factors, thereby eliciting the expression of protective proteins. Consequently, this regulatory process governs central and peripheral metabolism, oxidative stress, inflammation, mitochondrial function, autophagy, and the gut microbiota, all of which contribute to the amelioration of neurodegenerative disorders. Emerging evidence suggests that weight regulation significantly contributes to the neuroprotective effects of IF. By alleviating obesity-related factors such as blood-brain barrier dysfunction, neuroinflammation, and β-amyloid accumulation, IF enhances metabolic flexibility and insulin sensitivity, further supporting its potential in mitigating neurodegenerative disorders. The present review summarizes animal and human studies investigating the role and underlying mechanisms of IF in physiology and pathology, with an emphasis on its therapeutic potential. Furthermore, we provide an overview of the cellular and molecular mechanisms involved in regulating brain energy metabolism through IF, highlighting its potential applications in neurodegenerative disorders. Ultimately, our findings offer novel insights into the preventive and therapeutic applications of IF for neurodegenerative disorders.

The Detrimental Impact of Ultra-Processed Foods on the Human Gut Microbiome and Gut Barrier

Ultra-processed foods (UPFs) have become a widely consumed food category in modern diets. However, their impact on gut health is raising increasing concerns. This review investigates how UPFs impact the gut microbiome and gut barrier, emphasizing gut dysbiosis and increased gut permeability. UPFs, characterized by a high content of synthetic additives and emulsifiers, and low fiber content, are associated with a decrease in microbial diversity, lower levels of beneficial bacteria like Akkermansia muciniphila and Faecalibacterium prausnitzii, and an increase in pro-inflammatory microorganisms. These alterations in the microbial community contribute to persistent inflammation, which is associated with various chronic disorders including metabolic syndrome, irritable bowel syndrome, type 2 diabetes, and colorectal cancer. In addition, UPFs may alter the gut-brain axis, potentially affecting cognitive function and mental health. Dietary modifications incorporating fiber, fermented foods, and probiotics can help mitigate the effects of UPFs. Furthermore, the public needs stricter regulations for banning UPFs, along with well-defined food labels. Further studies are necessary to elucidate the mechanisms connecting UPFs to gut dysbiosis and systemic illnesses, thereby informing evidence-based dietary guidelines.

Role of Peripheral NLRP3 Inflammasome in Cognitive Impairments: Insights of Non-central Factors

Cognitive impairments are common clinical manifestation of Alzheimer's disease, vascular dementia, type 2 diabetes mellitus, and autoimmune diseases. Emerging evidence has suggested a strong correlation between peripheral chronic inflammation and cognitive impairments. For example, nearly 40% of individuals with inflammatory bowel disease also suffer from cognitive impairments. In this condition, NLRP3 inflammasome (NLRP3-I) generating pro-inflammatory cytokines like IL-1β serves as a significant effector, and its persistence exerts adverse effects to both periphery and the brain. Moreover, investigations on serum biomarkers of mild cognitive impairments have shown NLRP3-I components' upregulation, suggesting the involvement of peripheral inflammasome pathway in this disorder. Here, we systematically reviewed the current knowledge of NLRP3-I in inflammatory disease to uncover its potential role in bridging peripheral chronic inflammation and cognitive impairments. This review summarizes the molecular features and ignition process of NLRP3-I in inflammatory response. Meanwhile, various effects of NLRP3-I involved in peripheral inflammation-associated disease are also reviewed, especially its chronic disturbances to brain homeostasis and cognitive function through routes including gut-brain, liver-brain, and kidney-brain axes. In addition, current promising compounds and their targets relative to NLRP3-I are discussed in the context of cognitive impairments. Through the detailed investigation, this review highlights the critical role of peripheral NLRP3-I in the pathogenesis of cognitive disorders, and offers novel perspectives for developing effective therapeutic interventions for diseases associated with cognitive impairments. The present review outlines the current knowledge on the ignition of NLRP3-I in inflammatory disease and more importantly, emphasizes the role of peripheral NLRP3-I as a causal pathway in the development of cognitive disorders. Although major efforts to restrain cognitive decline are mainly focused on the central nervous system, it has become clear that disturbances from peripheral immune are closely associated with the dysfunctional brain. Therefore, attenuation of these inflammatory changes through inhibiting the NLRP3-I pathway in early inflammatory disease may reduce future risk of cognitive impairments, and in the meantime, considerations on such pathogenesis for combined drug therapy will be required in the clinical evaluation of cognitive disorders.

Mannuronate Oligosaccharides Ameliorate Experimental Colitis and Secondary Neurological Dysfunction by Manipulating the Gut-Brain Axis

Microbiota dysfunction induces intestinal disorders and neurological diseases. Mannuronate oligosaccharides (MAOS), a kind of alginate oligosaccharide (AOS), specifically exert efficacy in shaping gut microbiota and relieving cognitive impairment. However, the key regulatory factors involved, such as the specific strains and metabolites as well as their regulatory mechanisms, remain unclear at present. This research investigates how MAOS specifically impact the gut-brain axis in vivo and in vitro. The results showed that pretreatment with MAOS significantly ameliorated dextran sodium sulfate (DSS)-induced colitis and secondary nerve injury. This preventive mechanism operates through the regulation of serum DOPC abundance and the gut-brain axis, achieved by inhibiting the TLR4/MyD88/NF-κB pathway. These findings underscore the crucial role of dietary MAOS in the prevention of colitis and neurological disorders, providing a rationale for the application of MAOS in disease prevention and functional food ingredients.

Soymilk yogurt prepared using Pediococcus pentosaceus TOKAI 759m ameliorates cognitive function through gut microbiota modulation in high-fat diet mice

Recent studies have confirmed that obesity leads to neuroinflammation and cognitive decline. This study aimed to examine whether soymilk yogurt prepared using Pediococcus pentosaceus TOKAI 759m could prevent cognitive decline and neuroinflammation progression in mice fed a high-fat diet (HFD). C57BL/6NJcl male mice were grouped according to the following dietary interventions and monitored for 15 weeks: (1) normal control diet, (2) HFD, (3) HFD with soymilk (SM), (4) HFD with soymilk yogurt (SY), and (5) HFD with bacterial cells of the starter strain (BC). The levels of inflammatory cytokines in serum and hippocampus were measured. Compared to the HFD group, the SY group scored higher in the novel object recognition test and exhibited lower levels of Interleukin-6 (IL-6) and Tumor Necrosis Factor (TNF)-α in the hippocampus. However, the SM and BC groups did not show these significant changes. Proteomic analysis of the hippocampus revealed three enriched protein clusters in the SY group: synaptic proteins, glycolysis, and mitochondrial ATP formation. Fecal samples were also collected to measure the proportion of gut microbiota using 16S rRNA analysis. Interestingly, the proportion of butyrate-producing bacteria, such as Clostridium and Akkermansia, tended to be higher in the SY group than in the HFD group. An additional in vitro study revealed that the components of SY, such as daidzein, genistein, and adenine, could decrease inflammatory cytokine levels in microglial cells. In conclusion, soymilk yogurt prepared using P. pentosaceus TOKAI 759m may modulate gut microbiota and prevent neuroinflammation, thereby leading to a possible improvement in cognitive function.

Unlocking the Vitamin Puzzle: Investigating Levels in People With Alzheimer's Disease Versus Healthy Controls Through Systematic Review and Network Meta-Analysis

The progression of Alzheimer's disease (AD) is intricately tied to the impairment of neurons, crucial for neurological functions. Despite extensive research, the precise mechanism underlying AD development remains elusive due to its multifaceted aetiology. Vitamin deficiency has emerged as a notable contributor to AD onset and progression, exerting a significant influence on brain function. To explore this link, we conducted a thorough review using PubMed, Web of Science and MEDLINE databases to gather literature on average vitamin concentrations in people with AD and healthy controls. Applying frequentist network meta-analysis techniques, we calculated standardised mean differences (SMDs) in vitamin concentrations between AD and control groups, both directly and indirectly. Our analysis, based on 67 articles, revealed statistically significant findings for various vitamins. Notably, vitamin C displayed the most substantial difference in average concentration between AD and control groups, supported by a high p-score of 0.92. Other vitamins that showed significant differences included vitamin D, folate, vitamin E, vitamin A and vitamin B12. Moreover, by considering alternative reference groups of vitamins, we derived indirect estimates, which further emphasised the role of vitamins in AD pathology. The ranking of vitamins based on their discrepancy in concentration between AD and control groups underscored the importance of vitamin C, followed by vitamin D, vitamin E, folate, vitamin A and vitamin B12. In conclusion, our comprehensive analysis highlights the potential significance of vitamin levels in understanding AD pathology. This underscores avenues for further research and potential therapeutic interventions targeting vitamin deficiencies in people with AD, potentially offering new strategies for managing the disease. Trial Registration: CRD42023447203.

Pleiotrophin deletion prevents high-fat diet-induced cognitive impairment, glial responses, and alterations of the perineuronal nets in the hippocampus

Obesity and metabolic disorders, such as metabolic syndrome (MetS) facilitate the development of neurodegenerative diseases and cognitive decline. Persistent neuroinflammation plays an important role in this process. Pleiotrophin (PTN) is a cytokine that regulates energy metabolism and high-fat diet (HFD)-induced neuroinflammation, suggesting that PTN could play an important role in the connection between obesity and brain alterations, including cognitive decline. To test this hypothesis, we used an HFD-induced obesity model in Ptn genetically deficient mice (Ptn-/-). First, we confirmed that Ptn deletion prevents HFD-induced obesity. Our findings demonstrate that feeding wild-type (Ptn+/+) mice with HFD for 6 months results in short- and long-term memory loss in the novel object recognition task. Surprisingly, we did not observe any sign of cognitive impairment in Ptn-/- mice fed with HFD. In addition, we observed that HFD induced microglial responses, astrocyte depletion, and perineuronal nets (PNNs) alterations in Ptn+/+ mice, while these effects of HFD were mostly prevented in Ptn-/- mice. These results show a crucial role of PTN in metabolic responses and brain alterations induced by HFD and suggest the PTN signalling pathway as a promising therapeutic target for brain disorders associated with MetS.

Liraglutide and denatonium benzoate attenuate T2DM-induced metabolic, neurological, and testicular changes in rats: Targeting oxidative stress, inflammation, and BCRP transporter

Type 2 diabetes mellitus (T2DM) adversely affects various organs, including the brain and its blood barrier. In addition to the brain, hyperglycemia damages the testes. The testes possess blood-tissue barriers that share common characteristics and proteins with the blood-brain barrier (BBB), including breast cancer-resistant protein (BCRP). This study aimed to investigate the impact of uncontrolled DM on the brain and testes, with a specific focus on BCRP. Moreover, it examined the effects of liraglutide (Lira) and denatonium benzoate (DB), a bitter taste receptor agonist, on T2DM. Forty adult male rats were randomized into five groups: normal control, diabetic, diabetic + DB, diabetic + Lira, and diabetic + DB + Lira. T2DM was induced using fructose and streptozotocin (STZ). After eight weeks of treatment, rats were sacrificed, and samples of blood, semen, testes, and brain were collected to evaluate metabolic and semen parameters, oxidative stress, inflammatory markers, histological features of the brain and testes, and BCRP expression. DB and Lira, both individually and in combination, mitigated fructose/STZ-induced hyperglycemia and dyslipidemia. Additionally, they enhanced SOD activity and reduced MDA, TNFα, and IL-6 levels in the brain and testes, alongside improving sperm quality and serum levels of FSH, LH, and testosterone. Rats treated with DB, Lira, or DB + Lira demonstrated improved brain and testicular tissue architecture. BCRP expression was upregulated in the brains and testes of Lira- and DB + Lira-treated rats. These findings indicated that DB positively affects the metabolic profile of T2DM. Furthermore, Lira and DB provided protection against T2DM-induced brain and testicular damage.

Dietary Intake, Mediterranean and Nordic Diet Adherence in Alzheimer's Disease and Dementia: A Systematic Review

BACKGROUND/OBJECTIVES

Dementia is not a single disease but an umbrella term that encompasses a range of symptoms, such as memory loss and cognitive impairments, which are severe enough to disrupt daily life. One of the most common forms of dementia is Alzheimer's Disease (AD), a complex neurodegenerative condition influenced by both genetic and environmental factors. Recent research has highlighted diet as a potential modifiable risk factor for AD. Decades of research have explored the role of dietary patterns, including the Mediterranean Diet (MD) and its components, in neuroprotection and cognitive health. Systematic review examines studies investigating the impact of the Mediterranean Diet, Mediterranean-like diets, the Nordic Diet (ND), dietary intake patterns, and specific components such as extra virgin olive oil and rapeseed oil on cognitive function, disease onset, and progression in AD and dementia.

METHODS

A comprehensive search of PubMed, the Directory of Open Access Journals, and the Social Science Research Network was conducted independently by two reviewers using predefined search terms. The search period included studies from 2006 to 2024. Eligible studies meeting the inclusion criteria were systematically reviewed, yielding 88 studies: 85 focused on the MD and its relationship to AD and dementia, while only 3 investigated the ND.

RESULTS

The findings suggest that adherence to the Mediterranean and Nordic diets is generally associated with improved cognitive function and delayed cognitive decline and that adherence to both these diets can improve cognitive function. Some studies identified that higher legume consumption decreased dementia incidence, while fruits and vegetables, carbohydrates, and eggs lowered dementia prevalence. Most studies demonstrated that high MD or ND adherence was associated with better cognitive function and a lower risk of poor cognition in comparison to individuals with lower MD or ND adherence. However, some studies reported no significant benefits of the MD on cognitive outcomes, while two studies indicated that higher red meat consumption was linked to better cognitive function.

CONCLUSION

Despite promising trends, the evidence remains varying across studies, underscoring the need for further research to establish definitive associations between diet and cognitive function. These findings highlight the essential role of dietary interventions in the prevention and management of dementia and AD, therefore offering critical insights into the underlying mechanisms by which the diet may impact brain health.

The Association Between Metabolic Score for Visceral Fat and Cognitive Function Among Older Adults in the United States

BACKGROUND

Although several studies have demonstrated a link between obesity and cognitive function, the majority have primarily utilized body mass index (BMI) and waist circumference, ignoring the distribution of body fat. Evidence regarding the association of metabolic score for visceral fat (METS-VF), a proposed measurement for visceral adipose tissue (VAT), with cognitive function remains limited. We mainly aimed to investigate this association in older adults in the United States.

METHODOLOGY

Data were from the National Health and Nutrition Examination Survey (NHANES) 2011 to 2014. Weighted linear regression models were adopted to examine the association of METS-VF and cognitive function scores, with further exploration of these associations across different obesity subgroups. Smoothing curve analysis, along with threshold and saturation effect analysis, were conducted to explore potential non-linear relationships.

RESULTS

In the multivariable-adjusted model, participants in the highest quartile (Quartile 4) of METS-VF exhibited a β coefficient of -1.52 [95% CI (-2.43, -0.62)] for the CERAD score compared with those in the lowest quartile (Quartile 1). Threshold and saturation effect analysis revealed non-linear associations of METS-VF with DSST score and Z-score.

CONCLUSIONS

The findings of this study indicate that elevated METS-VF scores are inversely related to cognitive function, highlighting the importance of considering visceral fat distribution in cognitive health assessments.

Maternal Diet and Vulnerability to Cognitive Impairment in Adulthood: Possible Link with Alzheimer's Disease?

BACKGROUND

Aging is the main risk factor for developing cognitive impairments and associated neurodegenerative diseases. However, environmental factors, including nutritional health, are likely to promote or reduce cognitive impairments and neurodegenerative pathologies. An intricate relationship exists between maternal nutrition and adult eating behavior, metabolic phenotype, and cognitive abilities.

SUMMARY

The objective of the present review was to collect available data, suggesting a link between maternal overnutrition and the latter impairment of cognitive functions in the progeny, and to relate this relationship with Alzheimer's disease (AD). Indeed, cognitive impairments are major behavioral signs of AD. We first reviewed studies showing an association between unbalanced maternal diet and cognitive impairments in the progeny in humans and rodent models. Then we looked for cellular and molecular hallmarks which could constitute a breeding ground for AD in those models. With this end, we focused on synaptic dysfunction, altered neurogenesis, neuroinflammation, oxidative stress, and pathological protein aggregation. Finally, we proposed an indirect mechanism linking maternal unbalanced diet and progeny's vulnerability to cognitive impairments and neurodegeneration through promoting metabolic diseases. We also discussed the involvement of progeny's gut microbiota in the maternal diet-induced vulnerability to metabolic and neurodegenerative diseases.

KEY MESSAGES

Further investigations are needed to fully decipher how maternal diet programs the fetus and infant brain. Addressing this knowledge gap would pave the way to precise nutrition and personalized medicine to better handle cognitive impairments in adulthood.

Quantitative Blood Serum IVDr NMR Spectroscopy in Clinical Metabolomics of Cancer, Neurodegeneration, and Internal Medicine

Despite more than two decades of metabolomics having joined the "omics" scenery, to date only a few novel blood metabolite biomarkers have found their way into the clinic. This is changing now by massive large-scale population metabolic phenotyping for both healthy and disease cohorts. Here, nuclear magnetic resonance (NMR) spectroscopy is a method of choice, as typical blood serum markers can be easily quantified and by knowledge of precise reference concentrations, more and more NMR-amenable biomarkers are established, moving NMR from research to clinical application. Besides customized approaches, to date two major commercial platforms have evolved based on either 600 MHz (14.1 Tesla) or 500 MHz (11.7 Tesla) high-field NMR systems. This chapter provides an introduction into the field of quantitative in vitro diagnostics research (IVDr) NMR at 600 MHz and its application within clinical research of cancer, neurodegeneration, and internal medicine.

Leisure activity engagement attenuates the risks of cognitive impairment induced by unhealthy plant-based diets: a nationwide cohort study

OBJECTIVE

We intended to reveal the joint effects between LAE and uPDI on cognition in Chinese older adults.

METHODS

Data were collected from the Chinese Longitudinal Healthy Longevity Survey. In total, 10,617 individuals aged 65 years and above without cognitive impairment or dementia at baseline were enrolled in 2008 and followed up in 2011, 2014, and 2018. The uPDI and the scores of LAE were derived from survey responses, and both were categorized into three groups (low, intermediate, and high). Individuals with a Mini-Mental State Examination (MMSE) score lower than 18 were considered to have cognitive impairment. Cox proportional hazards models were employed to explore the joint association of uPDI and LAE on cognitive impairment, followed by restricted cubic spline (RCS) to observe the effects of the continuous-type variable of uPDI and the scores of LAE on the risk of cognitive impairment. Stratified analysis was applied to examine the association of LAE with cognitive impairment in uPDI groups (high uPDI vs. low uPDI).

RESULTS

Compared to participants maintained low scores of LAE and high uPDI, those who maintained high scores of LAE and low uPDI had a decreased risk of cognitive impairment (HR = 0.52, 95% CI, 0.43-0.62). The findings of the stratified analysis demonstrated that the protective effects of high scores of LAE on cognition was pronounced in individuals with low uPDI (HR = 0.61, 95% CI: 0.47-0.79) and those with high uPDI (HR = 0.63, 95% CI: 0.51-0.78).

CONCLUSIONS

In this cohort study, a higher score of uPDI, which indicated higher intake of salt-preserved vegetables, sugars, and refined grains, was associated with an increased risk of cognitive impairment, whereas this association may be mitigated by regular engagement in leisure activities.

Association between dietary inflammatory index score and incident dementia

INTRODUCTION

We evaluated whether higher Dietary Inflammatory Index (DII) scores were associated with increased incidence of all-cause dementia and Alzheimer's disease (AD) dementia over 22.3 years of follow-up in the community-based Framingham Heart Study Offspring cohort.

METHODS

One thousand four hundred eighty-seven participants (mean ± standard deviation, age in years 69 ± 6) completed food frequency questionnaires (FFQs) and had incident all-cause dementia and AD surveillance data available.

RESULTS

Two hundred forty-six participants developed all-cause dementia (including AD, n = 187) over a median follow-up time of 13.1 years. Higher DII scores, averaged across a maximum of three timepoints, were associated with an increased incidence of all-cause dementia and AD after adjustment for demographic, lifestyle, and clinical covariates (hazard ratio [HR] 1.21, 95% confidence interval [CI] 1.10-1.33, P < 0.001; HR 1.20, 95% CI: 1.07-1.34d, P = 0.001, respectively).

DISCUSSION

Higher DII scores were associated with a higher risk of incident all-cause dementia and AD. Although these promising findings need to be replicated and further validated, our results suggest that diets that correlate with low DII scores may prevent late-life dementia.

HIGHLIGHTS

Higher Dietary Inflammatory Index (DII) scores were associated with an increased incidence of all-cause dementia. Higher DII scores were associated with an increased incidence of Alzheimer's disease dementia. Diets that correlate with low DII scores may prevent late-life dementia.

Excessive Alcohol Use as a Risk Factor for Alzheimer's Disease: Epidemiological and Preclinical Evidence

Alcohol use has recently emerged as a modifiable risk factor for Alzheimer's disease (AD). However, the neurobiological mechanisms by which alcohol interacts with AD pathogenesis remain poorly understood. In this chapter, we review the epidemiological and preclinical support for the interaction between alcohol use and AD. We hypothesize that alcohol use increases the rate of accumulation of specific AD-relevant pathologies during the prodromal phase and exacerbates dementia onset and progression. We find that alcohol consumption rates are increasing in adolescence, middle age, and aging populations. In tandem, rates of AD are also on the rise, potentially as a result of this increased alcohol use throughout the lifespan. We then review the biological processes in common between alcohol use disorder and AD as a means to uncover potential mechanisms by which they interact; these include oxidative stress, neuroimmune function, metabolism, pathogenic tauopathy development and spread, and neuronal excitatory/inhibitory balance (EIB). Finally, we provide some forward-thinking suggestions we believe this field should consider. In particular, the inclusion of alcohol use assessments in longitudinal studies of AD and more preclinical studies on alcohol's impacts using better animal models of late-onset Alzheimer's disease (LOAD).

Long-Term High-Fat Diet Impairs AQP4-Mediated Glymphatic Clearance of Amyloid Beta

As a risk factor for Alzheimer's disease (AD), studies have demonstrated that long-term high-fat diet (HFD) could accelerate the deposition of amyloid beta (Aβ) in the brain. The glymphatic system plays a critical role in Aβ clearance from the brain. However, studies investigating the effects of long-term HFD on glymphatic function have reported paradoxical outcomes, and whether glymphatic dysfunction is involved in the disturbance of Aβ clearance in long-term HFD-fed mice has not been determined. In the present study, we injected fluorescently labeled Aβ into the hippocampus and found that Aβ clearance was decreased in HFD-fed mice. We found that long-term HFD-fed mice had decreased glymphatic function by injecting fluorescent tracers into the cisterna magna and corpus striatum. In long-term HFD-fed mice, aquaporin-4 (AQP4) polarization in the cortex was disrupted, and glymphatic clearance activity was positively correlated with the AQP4 polarization index. In HFD-fed mice, the disturbance of Aβ clearance from the hippocampus was exacerbated by TGN-020, a specific inhibitor of AQP4, whereas TGN-073, an enhancer of AQP4, ameliorated it. These findings suggest that long-term HFD disrupts Aβ clearance by inhibiting AQP4-mediated glymphatic function. The underlying mechanism may involve the disruption of AQP4 polarization.

Water Extract of Djulis Husk Exerts Protective Effect Against Metabolic Syndrome

Djulis (Chenopodium formosanum Koidz.) possesses various biological activities, including anti-oxidant, anti-hyperglycemic, anti-aging and hepatoprotective properties. Although djulis husk is typically considered agricultural waste, there is value in exploring ways to utilize it effectively. This study aimed to investigate the protective effects of the water extract of djulis husk (WDH) in rats with high-fructose-induced metabolic syndrome. The results showed that WDH significantly ameliorated the metabolic syndrome induced by a high-fructose diet in rats. Supplementation with low-dose WDH (0.5% of diet, w/w) significantly improved metabolic syndrome, including high blood pressure, hypertriglyceridemia, and insulin resistance. The protective effects of WDH against metabolic syndrome may be associated with increased expression of the genes encoding insulin receptor substrates-1 (IRS-1) and glucose transporter 4 (GLUT-4) in the epididymal fat. Thus, WDH is likely a functional food ingredient for the prevention of metabolic syndrome.

Evaluating sex-specific responses to western diet across the lifespan: impact on cardiac function and transcriptomic signatures in C57BL/6J mice at 530 and 640/750 days of age

BACKGROUND

Long-term consumption of Western Diet (WD) is a well-established risk factor for the development of cardiovascular disease (CVD); however, there is a paucity of studies on the long-term effects of WD on the pathophysiology of CVD and sex-specific responses.

METHODS

Our study aimed to investigate the sex-specific pathophysiological changes in left ventricular (LV) function using transthoracic echocardiography (ECHO) and LV tissue transcriptomics in WD-fed C57BL/6 J mice for 125 days, starting at the age of 300 through 425 days.

RESULTS

In female mice, consumption of the WD diet showed long-term effects on LV structure and possible development of HFpEF-like phenotype with compensatory cardiac structural changes later in life. In male mice, ECHO revealed the development of an HFrEF-like phenotype later in life without detectable structural alterations. The transcriptomic profile revealed a sex-associated dichotomy in LV structure and function. Specifically, at 530-day, WD-fed male mice exhibited differentially expressed genes (DEGs), which were overrepresented in pathways associated with endocrine function, signal transduction, and cardiomyopathies. At 750 days, WD-fed male mice exhibited dysregulation of several genes involved in various lipid, glucagon, and glutathione metabolic pathways. At 530 days, WD-fed female mice exhibited the most distinctive set of DEGs with an abundance of genes related to circadian rhythms. At 640 days, altered DEGs in WD-fed female mice were associated with cardiac energy metabolism and remodeling.

CONCLUSIONS

Our study demonstrated distinct sex-specific and age-associated differences in cardiac structure, function, and transcriptome signature between WD-fed male and female mice.

Foods, dietary patterns, and risk of vascular dementia: a systematic review

BACKGROUND

Vascular dementia (VaD) is the second most common cause of dementia globally and is associated with a significant economic and social burden. Diet could represent an important tractable risk factor for VaD. We synthesised current evidence on associations between consumption of specific foods or dietary patterns and VaD risk.

METHODS

Five databases were searched from inception to January 2024 for prospective cohort studies exploring associations between individual foods or dietary patterns and incident VaD.

RESULTS

Sixteen studies were included. Compared with low intake reference groups, higher fruit and vegetable intake, moderate alcoholic drink intake (1-3 drinks/day), higher tea and coffee intake, and following a plant-based dietary pattern were associated with lower VaD risk. Conversely, moderate fried fish intake (0.25-2 servings/week), higher ultra-processed food intake (especially intake of sweetened beverages) and higher processed meat intake (≥ 2 servings/week) were associated with increased VaD risk. Inconsistent findings were observed for other dietary exposures.

DISCUSSION

A healthy diet could lower VaD risk. However, evidence is characterised by a limited number of studies for specific dietary exposures. Further research is needed to inform personalised and population-based approaches to lower VaD risk.

Impact of Mast Cell Activation on Neurodegeneration: A Potential Role for Gut-Brain Axis and Helicobacter pylori Infection

BACKGROUND

The innate immune response aims to prevent pathogens from entering the organism and/or to facilitate pathogen clearance. Innate immune cells, such as macrophages, mast cells (MCs), natural killer cells and neutrophils, bear pattern recognition receptors and are thus able to recognize common molecular patterns, such as pathogen-associated molecular patterns (PAMPs), and damage-associated molecular patterns (DAMPs), the later occurring in the context of neuroinflammation. An inflammatory component in the pathology of otherwise "primary cerebrovascular and neurodegenerative" disease has recently been recognized and targeted as a means of therapeutic intervention. Activated MCs are multifunctional effector cells generated from hematopoietic stem cells that, together with dendritic cells, represent first-line immune defense mechanisms against pathogens and/or tissue destruction.

METHODS

This review aims to summarize evidence of MC implication in the pathogenesis of neurodegenerative diseases, namely, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, and multiple sclerosis.

RESULTS

In view of recent evidence that the gut-brain axis may be implicated in the pathogenesis of neurodegenerative diseases and the characterization of the neuroinflammatory component in the pathology of these diseases, this review also focuses on MCs as potential mediators in the gut-brain axis bi-directional communication and the possible role of Helicobacter pylori, a gastric pathogen known to alter the gut-brain axis homeostasis towards local and systemic pro-inflammatory responses.

CONCLUSION

As MCs and Helicobacter pylori infection may offer targets of intervention with potential therapeutic implications for neurodegenerative disease, more clinical and translational evidence is needed to elucidate this field.

Organic food consumption is positively associated with cognitive function among middle-aged and older adults: cross-sectional and longitudinal analyses

PURPOSE

Examine cross-sectional and longitudinal relationships between organic food consumption and cognitive function among older adults.

METHODS

In this study, 6077 participants were selected from the 2012 Health and Retirement Study (HRS) and the Health Care and Nutrition Study (HCNS) for cross-sectional analyses, and retaining 4882 individuals for longitudinal analyses. Organic food consumption was assessed using a Food Frequency Questionnaire and participants were categorized based on their organic dietary diversity score. Cognitive function was evaluated using the Langa-Weir classification. A multivariable linear analysis was used to investigate the associations between organic food consumption and cognitive function. Cox proportional hazards model examined the association between mild cognitive impairment (MCI) and organic food consumption.

RESULTS

Our findings revealed a positive association between the organic food consumption and cognitive function among older adults. However, the consumption of organic food was found to significantly reduce the risk of MCI only among females, with a hazard ratio of 0.80 (95% CI 0.65-0.98). Furthermore, both organic animal and plant food consumption were independently linked to a 27% and 20% reduction in the risk of incident MCI, respectively.

CONCLUSION

This research results underscores the cognitive benefits of organic diets, particularly in mitigating the risk of MCI among females. Recognizing the sex-specific nature of this association suggests the importance of considering gender perspectives in the formulation of dietary interventions aimed at cognitive health.

Single-cell transcriptome unveils unique transcriptomic signatures of human organ-specific endothelial cells

The heterogeneity of endothelial cells (ECs) across human tissues remains incompletely inventoried. We constructed an atlas of > 210,000 ECs derived from 38 regions across 24 human tissues. Our analysis reveals significant differences in transcriptome, phenotype, metabolism and transcriptional regulation among ECs from various tissues. Notably, arterial, venous, and lymphatic ECs shared more common markers in multiple tissues than capillary ECs, which exhibited higher heterogeneity. This diversity in capillary ECs suggests their greater potential as targets for drug development. ECs from different tissues and vascular beds were found to be associated with specific diseases. Importantly, tissue specificity of EC senescence is more determined by somatic site than by tissue type (e.g. subcutaneus adipose tissue and visceral adipose tissue). Additionally, sex-specific differences in brain EC senescence were observed. Our EC atlas offers valuble resoursce for identifying EC subclusters in single-cell datasets from body tissues or organoids, facilitating the screen of tissue-specific targeted therapies, and serving as a powerful tool for future discoveries.

New insight on the potential detrimental effect of metabolic syndrome on the Alzheimer disease neuropathology: Mechanistic role

The metabolic syndrome or syndrome X is a clustering of different components counting insulin resistance (IR), glucose intolerance, visceral obesity, hypertension and dyslipidemia. It has been shown that IR and dysregulation of insulin signalling play a critical role in the development of metabolic syndrome by initiating the pathophysiology of metabolic syndrome through induction of glucolipotoxicity, impairment of glucose disposal and triggering of pro-inflammatory response. Furthermore, metabolic syndrome unfavourably affects the cognitive function and the development of different neurodegenerative diseases such as Alzheimer disease (AD) by inducing oxidative stress, neuroinflammation and brain IR. These changes together with brain IR impair cerebrovascular reactivity leading to cognitive impairment. In addition, metabolic syndrome increases the risk for the development of AD. However, the central mechanisms by which metabolic syndrome amplify AD risk are not completely elucidated. Consequently, this narrative review aims to revise from published articles the association between metabolic syndrome and AD regarding cellular and subcellular pathways. In conclusion, metabolic syndrome is regarded as a potential risk factor for the induction of AD neuropathology by different signalling pathways such as initiation of brain IR, activation of inflammatory signalling pathways and neuroinflammation.

Chronic Obstructive Pulmonary Disease: The Role of Healthy and Unhealthy Dietary Patterns-A Comprehensive Review

Chronic obstructive pulmonary disease (COPD) is a progressive and irreversible disease affecting many people worldwide. Recent evidence suggests that diet and lifestyle play a vital role in COPD progression. We aimed to provide a comprehensive review of the effect of healthy and unhealthy dietary patterns on preventing and treating COPD. For this reason, Scopus, EMBASE, Web of Science, and PubMed were searched. Based on our findings, it appears that adhering to a healthy dietary pattern rich in vegetables, legumes, fruit, nuts, and whole grains may have advantageous impacts on preventing and treating COPD while following an unhealthy dietary pattern rich in red and processed meat, saturated fats, sweets, and sugary drinks affect COPD negatively. Adhering to Mediterranean, dietary approaches to stop hypertension (DASH), Prudent, Ketogenic, and High-protein diet may be related to a lower risk of COPD and improved pulmonary function. Conversely, Western and Ramadan Intermittent Fasting diets may elevate the prevalence of COPD. Proposing a nutritious diet that enhances pulmonary function could potentially be an effective approach to preventing and managing COPD. A comprehensive knowledge of the relationship between dietary factors and COPD can provide healthcare professionals with properly supported approaches to advise patients and empower individuals to make informed lifestyle decisions that are beneficial to improve their pulmonary health.

The triglyceride-glucose index and risk of cognitive impairment: a systematic review and meta-analysis with inclusion of two national databases

Background

To investigate the relationship between the triglyceride and glucose (TyG) index and cognitive impairment (CI).

Methods

Five authoritative databases were systematically searched for potentially relevant studies on 'TyG index' and 'CI' from inception to 27 April 2024. Two representative databases from the United Kingdom and United States were also included. We used the PICOS criteria to select available articles. All data was combined to compute Odd Ratios (ORs).

Results

15 studies were included in the meta-analysis (participants: 5604303). The pooled effect sizes demonstrate that individuals with a high TyG index exhibit a significantly elevated risk of CI compared to those with a low TyG index (OR = 2.16, 95%CI: 1.51; 3.08, p < 0.001). The subgroup analysis showed that inpatients with a high TyG index exhibited an increased risk of CI (OR = 4.56, 95%CI: 3.09; 6.74, p < 0.001). Furthermore, the risk of developing distinct types of CI differed significantly [CI: OR = 1.64, 95% CI: 1.29; 2.07, p < 0.001; Vascular Cognitive Impairment (VCI): OR = 5.39, 95% CI: 3.33; 8.70, p < 0.001].

Conclusion

A positive correlation exists between the TyG index and risk of CI, which has potential value in optimizing CI risk stratification among elderly people, especially those hospitalized.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023450336.

The Relationship Between Dietary Patterns, Cognition, and Cardiometabolic Health in Healthy, Older Adults

BACKGROUND

Healthy dietary patterns can support the maintenance of cognition and brain health in older age and are negatively associated with cardiometabolic risk. Cardiometabolic risk factors are similarly important for cognition and may play an important role in linking diet to cognition.

AIM

This study aimed to explore the relationship between dietary patterns and cognition and to determine whether cardiometabolic health markers moderate these relationships in older adulthood.

DESIGN

A cross-sectional analysis of observational data from the baseline of the ACTIVate study.

PARTICIPANTS

The cohort included 426 cognitively normal adults aged 60-70 years.

METHODS

The Australian Eating Survey (AES) Food Frequency Questionnaire was used to collect data on usual dietary intake, along with additional questions assessing intake of dietary oils. Principal component analysis (PCA) was applied to reduce the dimensionality of dietary data. Cardiometabolic risk was quantified using the metabolic syndrome severity score (MetSSS). Tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) were used to derive composite scores on four cognitive domains: processing speed, executive function, short-term memory, and long-term memory.

RESULTS

Three dietary patterns were identified using PCA: a plant-dominant diet, a Western-style diet, and a meat-dominant diet. After controlling for age, sex, total years of education, energy intake, and moderate-to-vigorous physical activity (MVPA), there was a small, negative association between the meat-dominant diets and long-term memory. Subsequent moderation analysis indicated that MetSSS significantly moderated this relationship.

CONCLUSIONS

Findings highlight the link between diet, cardiometabolic health, and cognitive function in older, cognitively healthy adults. However, longitudinal studies are needed to confirm observations and evaluate the dynamics of diet, cardiometabolic health, and cognitive function over time.

Gut Microbiota and Immune System Dynamics in Parkinson's and Alzheimer's Diseases

The gut microbiota, a diverse collection of microorganisms in the gastrointestinal tract, plays a critical role in regulating metabolic, immune, and cognitive functions. Disruptions in the composition of these microbial communities, termed dysbiosis, have been linked to various neurodegenerative diseases (NDs), such as Parkinson's disease (PD) and Alzheimer's disease (AD). One of the key pathological features of NDs is neuroinflammation, which involves the activation of microglia and peripheral immune cells. The gut microbiota modulates immune responses through the production of metabolites and interactions with immune cells, influencing the inflammatory processes within the central nervous system. This review explores the impact of gut dysbiosis on neuroinflammation, focusing on the roles of microglia, immune cells, and potential therapeutic strategies targeting the gut microbiota to alleviate neuroinflammatory processes in NDs.

The role of intestinal microbiota and metabolites in intestinal inflammation

With the imbalance of intestinal microbiota, the body will then face an inflammatory response, which has serious implications for human health. Bodily allergies, injury or pathogens infections can trigger or promote inflammation and alter the intestinal environment. Meanwhile, excessive changes in the intestinal environment cause the imbalance of microbial homeostasis, which leads to the proliferation and colonization of opportunistic pathogens, invasion of the body's immune system, and the intensification of inflammation. Some natural compounds and gut microbiota and metabolites can reduce inflammation; however, the details of how they interact with the gut immune system and reduce the gut inflammatory response still need to be fully understood. The review focuses on inflammation and intestinal microbiota imbalance caused by pathogens. The body reacts differently to different types of pathogenic bacteria, and the ingestion of pathogens leads to inflamed gastrointestinal tract disorders or intestinal inflammation. In this paper, unraveling the interactions between the inflammation, pathogenic bacteria, and intestinal microbiota based on inflammation caused by several common pathogens. Finally, we summarize the effects of intestinal metabolites and natural anti-inflammatory substances on inflammation to provide help for related research of intestinal inflammation caused by pathogenic bacteria.

Limosilactobacillus reuteri DSM 17938 relieves inflammation, endoplasmic reticulum stress, and autophagy in hippocampus of western diet-fed rats by modulation of systemic inflammation

The consumption of western diets, high in fats and sugars, is a crucial contributor to brain molecular alterations, cognitive dysfunction and neurodegenerative diseases. Therefore, a mandatory challenge is the individuation of strategies capable of preventing diet-induced impairment of brain physiology. A promising strategy might consist in the administration of probiotics that are known to influence brain function via the gut-brain axis. In this study, we explored whether Limosilactobacillus reuteri DSM 17938 (L. reuteri)-based approach can counteract diet-induced neuroinflammation, endoplasmic reticulum stress (ERS), and autophagy in hippocampus, an area involved in learning and memory, in rat fed a high fat and fructose diet. The western diet induced a microbiota reshaping, but L. reuteri neither modulated this change, nor the plasma levels of short-chain fatty acids. Interestingly, pro-inflammatory signaling pathway activation (increased NFkB phosphorylation, raised amounts of toll-like receptor-4, tumor necrosis factor-alpha, interleukin-6, GFAP, and Haptoglobin), as well as activation of ERS (increased PERK and eif2α phosphorylation, higher C/EBP-homologous protein amounts) and autophagy (increased beclin, P62-sequestosome-1, and LC3 II) was revealed in hippocampus of western diet fed rats. All these hippocampal alterations were prevented by L. reuteri administration, showing for the first time a neuroprotective role of this specific probiotic strain, mainly attributable to its ability to regulate western diet-induced metabolic endotoxemia and systemic inflammation, as decreased levels of lipopolysaccharide, plasma cytokines, and adipokines were also found. Therapeutic strategies based on the use of L. reuteri DSM17938 could be beneficial in reversing metabolic syndrome-mediated brain dysfunction and cognitive decline.

Nerolidol rescues hippocampal injury of diabetic rats through inhibiting NLRP3 inflammasome and regulation of MAPK/AKT pathway

Despite the observation of diabetes-induced brain tissue damage and impaired learning and memory, the underlying mechanism of damage remains elusive, and effective, targeted therapeutics are lacking. Notably, the NLRP3 inflammasome is highly expressed in the hippocampus of diabetic individuals. Nerolidol, a naturally occurring compound with anti-inflammatory and antioxidant properties, has been identified as a potential therapeutic option for metabolic disorders. However, the ameliorative capacity of nerolidol on diabetic hippocampal injury and its underlying mechanism remain unclear. Network pharmacology and molecular docking was used to predict the signaling pathways and therapeutic targets of nerolidol for the treatment of diabetes. Then established a diabetic rat model using streptozotocin (STZ) combined with a high-fat diet and nerolidol was administered. Morris water maze to assess spatial learning memory capacity. Hematoxylin and eosin and Nissl staining was used to detect neuronal damage in the diabetic hippocampus. Transmission electron microscopy was used to detect the extent of damage to mitochondria, endoplasmic reticulum (ER) and synapses. Immunofluorescence was used to detect GFAP, IBA1, and NLRP3 expression in the hippocampus. Western blot was used to detect apoptosis (Bcl-2, BAX, and Cleaved-Caspase-3); synapses (postsynaptic densifying protein 95, SYN1, and Synaptophysin); mitochondria (DRP1, OPA1, MFN1, and MFN2); ER (GRP78, ATF6, CHOP, and caspase-12); NLRP3 inflammasome (NLRP3, ASC, and caspase-1); inflammatory cytokines (IL-18, IL-1β, and TNF-α); AKT (P-AKT); and mitogen-activated protein kinase (MAPK) pathway (P-ERK, P-p38, and P-JNK) related protein expression. Network pharmacology showed that nerolidol's possible mechanisms for treating diabetes are the MAPK/AKT pathway and anti-inflammatory effects. Animal experiments demonstrated that nerolidol could improve blood glucose, blood lipids, and hippocampal neuronal damage in diabetic rats. Furthermore, nerolidol could improve synaptic, mitochondrial, and ER damage in the hippocampal ultrastructure of diabetic rats by potentially affecting synaptic, mitochondrial, and ER-related proteins. Further studies revealed that nerolidol decreased neuroinflammation, NLRP3 and inflammatory factor expression in hippocampal tissue while also decreasing MAPK pathway expression and enhancing AKT pathway expression. However, nerolidol improves hippocampal damage in diabetic rats cannot be shown to improve cognitive function. In conclusion, our study reveals for the first time that nerolidol can ameliorate hippocampal damage, neuroinflammation, synaptic, ER, and mitochondrial damage in diabetic rats. Furthermore, we suggest that nerolidol may inhibit NLRP3 inflammasome and affected the expression of MAPK and AKT. These findings provide a new experimental basis for the use of nerolidol to ameliorate diabetes-induced brain tissue damage and the associated disease.

Microglia and gut microbiota: A double-edged sword in Alzheimer's disease

The strong association between gut microbiota (GM) and brain functions such as mood, behaviour, and cognition has been well documented. Gut-brain axis is a unique bidirectional communication system between the gut and brain, in which gut microbes play essential role in maintaining various molecular and cellular processes. GM interacts with the brain through various pathways and processes including, metabolites, vagus nerve, HPA axis, endocrine system, and immune system to maintain brain homeostasis. GM dysbiosis, or an imbalance in GM, is associated with several neurological disorders, including anxiety, depression, and Alzheimer's disease (AD). Conversely, AD is sustained by microglia-mediated neuroinflammation and neurodegeneration. Further, GM and their products also affect microglia-mediated neuroinflammation and neurodegeneration. Despite the evidence connecting GM dysbiosis and AD progression, the involvement of GM in modulating microglia-mediated neuroinflammation in AD remains elusive. Importantly, deciphering the mechanism/s by which GM regulates microglia-dependent neuroinflammation may be helpful in devising potential therapeutic strategies to mitigate AD. Herein, we review the current evidence regarding the involvement of GM dysbiosis in microglia activation and neuroinflammation in AD. We also discuss the possible mechanisms through which GM influences the functioning of microglia and its implications for therapeutic intervention. Further, we explore the potential of microbiota-targeted interventions, such as prebiotics, probiotics, faecal microbiota transplantation, etc., as a novel therapeutic strategy to mitigate neuroinflammation and AD progression. By understanding and exploring the gut-brain axis, we aspire to revolutionize the treatment of neurodegenerative disorders, many of which share a common theme of microglia-mediated neuroinflammation and neurodegeneration.

Small molecule modulators of alpha-synuclein aggregation and toxicity: Pioneering an emerging arsenal against Parkinson's disease

Parkinson's disease (PD) is primarily characterized by loss of dopaminergic neurons in the substantia nigra pars compacta region of the brain and accumulation of aggregated forms of alpha-synuclein (α-Syn), an intrinsically disordered protein, in the form of Lewy Bodies and Lewy Neurites. Substantial evidences point to the aggregated/fibrillar forms of α-Syn as a central event in PD pathogenesis, underscoring the modulation of α-Syn aggregation as a promising strategy for PD treatment. Consequently, numerous anti-aggregation agents, spanning from small molecules to polymers, have been scrutinized for their potential to mitigate α-Syn aggregation and its associated toxicity. Among these, small molecule modulators like osmoprotectants, polyphenols, cellular metabolites, metals, and peptides have emerged as promising candidates with significant potential in PD management. This article offers a comprehensive overview of the effects of these small molecule modulators on the aggregation propensity and associated toxicity of α-Syn and its PD-associated mutants. It serves as a valuable resource for identifying and developing potent, non-invasive, non-toxic, and highly specific small molecule-based therapeutic arsenal for combating PD. Additionally, it raises pertinent questions aimed at guiding future research endeavours in the field of α-Syn aggregation remodelling.

Association between elevated systemic inflammatory markers and the risk of cognitive decline progression: a longitudinal study

BACKGROUND

Chronic systemic inflammation is linked to cognitive decline pathogenesis. This study investigates the association between systemic inflammation markers and cognitive decline progression in a clinical cohort.

METHODS

This prospective observational cohort study enrolled 295 participants. Cognitive decline progression was defined by an increase in clinical dementia rating (CDR) scores. The study examines the correlation between systemic inflammation markers, including systemic Inflammation Response Index (SIRI), systemic Immune-Inflammation Index (SII), prognostic Inflammatory and Nutritional Index (PIV), and cognitive impairment progression.

RESULTS

The presence of the APOE 4 allele and diabetes mellitus was associated with elevated PIV levels (P < 0.05). Additionally, AD patients had the highest SII levels, indicating increased inflammation compared to individuals with MCI and SCD (P < 0.05). After a mean follow-up of 17 months, 117 patients (51.31%) experienced cognitive decline progression. AD diagnosis, CDR, and SII were significant predictors of cognitive decline progression (All P < 0.05).

CONCLUSION

This study highlights the clinical significance of elevated systemic inflammation markers in identifying individuals at risk of cognitive decline. Addressing inflammation may offer a promising approach to improving cognitive health and mitigating age-related cognitive decline.

Dementia: Common Syndromes and Modifiable Risk and Protective Factors

Dementia is an umbrella term for multiple conditions that lead to progressive cognitive decline and impaired activities of daily living. Neuropsychological evaluation is essential for characterizing the distinct cognitive and behavioral profile that can aid in the diagnostic process and treatment planning for dementia. Modifiable risk factors for dementia such as nutrition, physical activity, sleep, cognitive and social engagement, and stress provide important avenues for prevention. Neurologists and other health care providers can help patients reduce their risk for dementia by providing them with education about modifiable factors and connecting them to resources to empower them to engage in brain-healthy behavior.

Physiopathological Roles of White Adiposity and Gut Functions in Neuroinflammation

White adipose tissue (WAT) and the gut are involved in the development of neuroinflammation when an organism detects any kind of injury, thereby triggering metainflammation. In fact, the autonomous nervous system innervates both tissues, although the complex role played by the integrated sympathetic, parasympathetic, and enteric nervous system functions have not been fully elucidated. Our aims were to investigate the participation of inflamed WAT and the gut in neuroinflammation. Firstly, we conducted an analysis into how inflamed peripheral WAT plays a key role in the triggering of metainflammation. Indeed, this included the impact of the development of local insulin resistance and its metabolic consequences, a serious hypothalamic dysfunction that promotes neurodegeneration. Then, we analyzed the gut-brain axis dysfunction involved in neuroinflammation by examining cell interactions, soluble factors, the sensing of microbes, and the role of dysbiosis-related mechanisms (intestinal microbiota and mucosal barriers) affecting brain functions. Finally, we targeted the physiological crosstalk between cells of the brain-WAT-gut axis that restores normal tissue homeostasis after injury. We concluded the following: because any injury can result not only in overall insulin resistance and dysbiosis, which in turn can impact upon the brain, but that a high-risk of the development of neuroinflammation-induced neurodegenerative disorder can also be triggered. Thus, it is imperative to avoid early metainflammation by applying appropriate preventive (e.g., lifestyle and diet) or pharmacological treatments to cope with allostasis and thus promote health homeostasis.

The Importance of Gut Microbiota on Choline Metabolism in Neurodegenerative Diseases

The gut microbiota is a complex ecosystem that influences digestion, immune response, metabolism, and has been linked to health and well-being. Choline is essential for neurotransmitters, lipid transport, cell-membrane signaling, methyl-group metabolism and is believed to have neuroprotective properties. It is found in two forms, water-soluble and lipid-soluble, and its metabolism is different. Long-term choline deficiency is associated with many diseases, and supplements are prescribed for improved health. Choline supplements can improve cognitive function in adults but not significantly. Choline is a precursor of phospholipids and an acetylcholine neurotransmitter precursor and can be generated de novo from phosphatidylcholine via phosphatidylethanolamine-N-methyltransferase and choline oxidase. Choline supplementation has been found to have a beneficial effect on patients with neurodegenerative diseases, such as Alzheimer's disease (AD), by increasing amyloid-β, thioflavin S, and tau hyper-phosphorylation. Choline supplementation has been shown to reduce amyloid-plaque load and develop spatial memory in an APP/PS1 mice model of AD. Choline is necessary for normative and improved function of brain pathways and can reduce amyloid-β deposition and microgliosis. Clinical research suggests that early neurodegenerative diseases (NDs) can benefit from a combination of choline supplements and the drugs currently used to treat NDs in order to improve memory performance and synaptic functioning.

Yeast β-glucan alleviates high-fat diet-induced Alzheimer's disease-like pathologies in rats via the gut-brain axis

Targeting the gut microbiota may be an emerging strategy for the prevention and treatment of Alzheimer's disease (AD). Macro-molecular yeast β-glucan (BG), derived from the yeast of Saccharomyces cerevisiae, regulates the gut microbiota. This study aimed to investigate the effect and mechanism of long-term BG in high-fat diet (HFD)-induced AD-like pathologies from the perspective of the gut microbiota. Here, we found that 80 weeks of BG treatment ameliorated HFD-induced cognitive dysfunction in rats. In the hippocampus, BG alleviated HFD-induced the activation of astrocytes, microglia, NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome pathway, and AD-like pathologies. BG modulated gut dysbiosis through increasing the levels of beneficial bacteria and short-chain fatty acids (SCFAs). BG also attenuated HFD-induced gut barrier impairment. Correlation analysis revealed a close relationship among microbiota, SCFAs, and AD-like pathologies. Furthermore, the fecal microbiota of BG-treated rats and SCFAs treatment mitigated AD-like pathologies via the NLRP3 inflammasome pathway in HFD-fed aged rats. These results suggested that long-term BG promotes the production of SCFAs derived from gut microbiota, which further inhibits NLRP3 inflammasome-mediated neuroinflammation, thereby alleviating HFD-induced AD-like pathologies in rats. BG may become a new strategy for targeting neurodegenerative diseases.

Brain energetics and glucose transport in metabolic diseases: role in neurodegeneration

OBJECTIVES

Neurons and glial cells are the main functional and structural elements of the brain, and the former depends on the latter for their nutritional, functional and structural organization, as well as for their energy maintenance.

METHODS

Glucose is the main metabolic source that fulfills energetic demands, either by direct anaplerosis or through its conversion to metabolic intermediates. Development of some neurodegenerative diseases have been related with modifications in the expression and/or function of glial glucose transporters, which might cause physiological and/or pathological disturbances of brain metabolism. In the present contribution, we summarized the experimental findings that describe the exquisite adjustment in expression and function of glial glucose transporters from physiologic to pathologic metabolism, and its relevance to neurodegenerative diseases.

RESULTS

A exhaustive literature review was done in order to gain insight into the role of brain energetics in neurodegenerative disease. This study made evident a critical involvement of glucose transporters and thus brain energetics in the development of neurodegenerative diseases.

DISCUSSION

An exquisite adjustment in the expression and function of glial glucose transporters from physiologic to pathologic metabolism is a biochemical signature of neurodegenerative diseases.

Diosmetin Ameliorates HFD-induced Cognitive Impairments via Inhibiting Metabolic Disorders, Mitochondrial Dysfunction and Neuroinflammation in Male SD Rats

Currently, accumulating evidence has indicated that overnutrition-associated obesity may result in not only metabolic dysregulations, but also cognitive impairments. This study aimed to investigate the protective effects of Diosmetin, a bioflavonoid compound with multiple biological functions, on cognitive deficits induced by a high fat diet (HFD) and the potential mechanisms. In the present study, oral administration of Diosmetin (25, 50 and 100 mg/kg) for 12 weeks significantly reduced the body weight, restored glucose tolerance and normalized lipid profiles in the serum and liver in HFD-induced obese rats. Diosmetin also significantly ameliorated depression-like behaviors and impaired spatial memory in multiple behavioral tests, including the open field test, elevated plus-maze and Morris water maze, which was in accordance with the decreased pathological changes and neuronal damage in different regions of hippocampus as suggested by H&E and Nissl staining. Notably, our results also indicated that Diosmetin could significantly improve mitochondrial dysfunction induced by HFD through upregulating genes involved in mitochondrial biogenesis and dynamics, increasing mitochondrial ATP levels and inhibiting oxidative stress. Moreover, the levels of key enzymes involved in the TCA cycle were also significantly increased upon Diosmetin treatment. Meanwhile, Diosmetin inhibited HFD-induced microglial overactivation and down-regulated inflammatory cytokines both in the serum and hippocampus. In conclusion, these results indicated that Diosmetin might be a novel nutritional intervention to prevent the occurrence and development of obesity-associated cognitive dysfunction via metabolic regulation and anti-inflammation.

Increased central obesity correlates with physical activity and food processing in recently diagnosed multiple sclerosis

BACKGROUND

Environmental and lifestyle factors are associated with an increased risk of Multiple Sclerosis (MS). Metabolic syndrome (MetS) contributes to systemic inflammation, which is associated with poorer MS disease evolution. We compared persons with MS (PwMS) and controls to assess metabolic and lifestyle parameters associated with MS.

METHODS

We pooled data from two prospective observational studies with the same eligibility criteria, matching PwMS and controls (1:2 ratio) by sex, age, and body mass index (BMI). We compared anthropometric, biological and lifestyle parameters, including sleep and physical activity.

RESULTS

We included 53 PwMS and 106 controls with a median age of 35 years and 79% of women. PwMS had low Expanded Disability Status Scale (median 1.5). Compared to controls, PwMS had increased waist-to-hip (p<0.001) and waist-to-height (p=0.007) ratios, and practiced less physical activity (p=0.03). In regression models, lifestyle factors with the strongest factor loadings to predict central obesity were processed food consumption, and vigorous physical activity.

DISCUSSION

Although both groups were matched by age, sex, and BMI, we found increased central obesity in PwMS. Even with minimal neurological impairment, PwMS practiced less physical activity. This suggests that improvement of lifestyle and metabolic parameters should be targeted in MS.