Marginal vitamin A deficiency facilitates Alzheimer's pathogenesis

Impact of vitamin A on aged people's cognition and Alzheimer's disease progression in an animal model

The relation between vitamin A (VA) level and cognitive function and the underlying mechanisms have not been thoroughly investigated. Population-based cross-sectional and animal diet intervention studies were conducted to analyze the association between VA nutritional status and cognitive function and the underlying mechanisms. In the population-based study, information from 1817 adults aged 50 years and above was used for data analysis, and we found that subjects with plasma VA level greater than 0.539 μg/ml displayed a lower risk of mild cognitive impairment (MCI). In the animal experiment, VA metabolism was disrupted in Alzheimer's disease (AD) model mice, indicated by increased hepatic VA level and reduced retinol binding protein 4 (RBP4) level. AD model mice fed with low-VA diet showed worse nesting behavior, and cerebral pathologies, including increased Aβ generation, exacerbated neuroinflammation, and impaired brain glucose uptake and insulin signaling pathway. In conclusion, higher plasma VA level (≥ 0.539 μg/ml) might decrease the risk of MCI in the middle-aged and elderly individuals. Low VA nutritional status might disrupt brain glucose metabolism through regulating the insulin signaling pathway, promoting the senile plaque deposit and aggregating cerebral neuroinflammation, finally exacerbating the pathology of AD.

Prenatal Exposure To Valproic Acid Induces Increased Autism-Like Behaviors and Impairment of Learning and Memory Functions in Rat Offspring by Upregulating ADAM10 Expression

Autism spectrum disorder (ASD) involves a complex neurodevelopmental pathogenesis. A disintegrin and metalloproteinase 10 (ADAM10) plays a crucial role in embryonic brain development and neural network stability. This study aimed to investigate the influence of ADAM10 on excitation/inhibition (E/I) balance, autism-like behaviors, and learning and memory dysfunction in rats prenatally exposed to valproic acid (VPA) and determine potential intervention strategies. The VPA-exposed group exhibited increased levels of ADAM10 and secreted amyloid precursor protein-α (sAPPα). Moreover, overexpression of glutamate decarboxylase 1 and N-methyl-D-aspartate receptors was observed. High-performance liquid chromatography-mass spectrometry revealed elevated levels of glutamate, glutamine, and γ-aminobutyric acid, as well as an E/I imbalance in the VPA group. Additionally, narrower synaptic clefts as well as increased postsynaptic density and synaptic vesicles were observed. Remarkably, intraperitoneal administration of ADAM10 inhibitor during the critical period of synaptic development significantly improved ASD-like behavior and learning and memory function in VPA-exposed rats. This intervention effectively reduced abnormally high sAPPα levels in the prefrontal cortex and corrected abnormal E/I balance. Thus, inhibiting ADAM10 overexpression may improve the E/I imbalance, alleviate core symptoms of ASD, and improve learning and memory dysfunction. The use of ADAM10 inhibitor represents a potential therapeutic strategy for treating ASD patients with intellectual disabilities.

Association of whole blood multi-micronutrients with mild cognitive impairment in Chinese older adults: a matched case-control study

PURPOSE

Adequate micronutrients play a crucial role in cognitive health. Identifying relevant micronutrients and constructing risk prediction models can guide the prevention of mild cognitive impairment (MCI) in older adults. This study aimed to assess the associations of MCI with whole blood micronutrient levels and develop a nomogram for personalized MCI risk prediction in older adults.

METHODS

In the matched case-control study, 100 MCI patients and 100 matched controls by age, sex and education from Baodi District, Tianjin, China were recruited. MCI was determined by a modified version of the Petersen criteria. Whole blood levels of 9 vitamins and 5 minerals were measured using the dried blood spot technique. Weighted quantile sum regression was employed to identify the most significant micronutrients associated with cognitive function. Receiver operating characteristic (ROC) curves were constructed, and a nomogram for predicting MCI risk was developed.

RESULTS

High levels of vitamins (vitamin A, vitamin B2, vitamin B6, vitamin B9) and minerals (magnesium, selenium) were significantly associated with lower MCI prevalence, in which vitamin B2, vitamin B9 and selenium were ranked as the most significant contributors to cognitive function. The ROC curves for vitamin B2 and vitamin B9 (area under the curve = 0.855) have superior diagnostic accuracy compared to individual assessments (p < 0.05). Based on these findings, a nomogram was developed using these two micronutrients to predict MCI risk.

CONCLUSION

The nomogram based on vitamin B2 and vitamin B9 can be effectively used to detect MCI early and guide preventive strategies in older adults.

Mechanistic insights into retinoic-acid treatment for autism in the improvement of social behavior: Evidence from a multi omics study in rats

BACKGROUND

Autism spectrum disorder (ASD) is a lifelong condition. It is characterized by complex etiologies, including disruptions in exogenous retinoic acid (RA) signaling, which may serve as an environmental risk factor. Targeting the RA pathway presents a promising therapeutic avenue, though the precise mechanisms remain to be elucidated.

METHODS

Female Sprague-Dawley rats were treated with valproic acid (VPA) during pregnancy to induce an ASD model in their offspring. Some offspring received RA treatment postnatally. Social behavior and brain-functional connectivity were assessed using behavioral tests and functional magnetic resonance imaging (fMRI), respectively. Transcriptomics analysis and proteomics analysis of the hypothalamus identified differentially expressed genes (DEGs) and differentially expressed proteins (DEPs). These were intersected with ASD pathogenic genes (APGs) and ASD pathogenic proteins (APPs) to identify differentially expressed APGs (DE-APGs) and differentially expressed APPs (DE-APPs), which were validated by real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting. Analyses of enrichment of signaling pathways were done using the Kyoto Encyclopedia of Genes and Genomes database.

RESULTS

RA treatment significantly improved social behaviors and revealed distinct patterns of hypo- and hyper-connectivity across various brain regions, with notable changes involving the hypothalamus and facial nerve. Differential analysis revealed 4165 DEGs (DEG 1) and 329 DEPs (DEP 1) between control and VPA groups, and 1610 DEGs (DEG 2) and 197 DEPs (DEP 2) between VPA and RA supplementation (RAS) groups. Twenty-two DE-APGs and five DE-APPs were identified, with key associations found between proteins such as Tbl1xr1 and Myo5a and >13 genes including Nrxn1, Cacna1e, and Gabrb2. Significant alterations in DE-APGs, including Grin2b, Nrxn1, Cacna1e, and Gabrb2, were confirmed via real-time RT-PCR and western blotting. In addition, 22 key signaling pathways were enriched in DEPs and DEGs.

CONCLUSION

RA supplementation in ASD rats induced by VPA may ameliorate social deficits and modulated functional connectivity, especially in the hypothalamus and facial nerve regions. This suggests potential therapeutic benefits for neural circuitry dysregulation in ASD. Additionally, RA altered critical gene and protein expressions in hypothalamus, implicating its role in modulating key signaling pathways to mitigate social deficits in ASD. This study provides new insights into the molecular mechanisms of ASD and supports the development of novel therapeutic strategies.

Portulaca oleracea L. Methanolic Extract Protects the Brain of Male Rats Against Alzheimer's Disease

Alzheimer's disease (AD) occurs as a result of a chronic neurodegenerative disorder that is most frequently linked to a decline in cognitive function and memory. Twenty-four male rats were divided into four groups (n = 6); Group I was the negative control, Group II was the AlCl3-positive control, and Group III and Group IV were treated with 100 mg and 200 mg/kg of Portulaca oleracea methanolic extract, respectively. Aluminum chloride intoxication in Group II increased lipid peroxidation and decreased antioxidant parameters and affected interleukin-6 (IL-6), the tumor necrosis factor-alpha (TNF-α), acetylcholinesterase (AChE), and amyloid beta (Aβ), which lead to the induction of AD through injuring brain cells of AD rats. Treating the AD rats in Group III (GIII) and Group IV (GIV) with P. oleracea ameliorated the altered parameters in the AD rats. It also increased folic acid and vitamin B12 levels. P. oleracea modulated the physiological, biochemical, and histological changes brought on by AlCl3 intoxication in rats via oxidative stress and inflammatory pathways. The dose of P. oleracea in GIV successfully modified the behavioral changes brought on by AlCl3 in the AD rats more than that of GIII.

Vitamins in the Prevention and Support Therapy of Neurodegenerative Diseases

Neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), which are a consequence of the progressive loss of neuronal function and structure, cause significant cognitive impairment. The incidence of these diseases in the world's population is constantly increasing as a result of an aging population. Although genetic and environmental factors are most often mentioned as the pathogenetic factors of these diseases, increasing evidence points to the important role of proper nutrition in the prevention and support of the treatment of these disorders. A healthy, balanced diet can mitigate the risks associated with the risk factors mentioned above and slow the progression of the disease by reducing oxidative stress and inflammation. Vitamins B, D, E, C, K, and A have been shown to support cognitive functions and protect the nervous system. This review demonstrates the importance of vitamins in preventing and supporting the therapy of neurodegenerative diseases. Information regarding the health-promoting properties of these vitamins must be effectively communicated to consumers seeking to protect their health, particularly in the context of neurodegenerative diseases. Consequently, this review also examines the authorized health claims under EU food law related to these vitamins, assessing their role in promoting awareness of the vitamins' potential benefits for neuroprotection and the management of neurodegenerative diseases.

Identification of circulating risk biomarkers for cognitive decline in a large community-based population in Chongqing China

INTRODUCTION

This study aims to investigate the relationship between blood-based pathologies and established risk factors for cognitive decline in the community-based population of Chongqing, a region with significant aging.

METHODS

A total of 26,554 residents aged 50 years and older were recruited. Multinomial logistic regression models were applied to assess the risk factors of cognition levels. Propensity score matching and linear mixed effects models were used to evaluate the relationship between key risk factors and the circulating biomarkers.

RESULTS

Shared and distinct risk factors for MCI and dementia were identified. Age, lower education, medical history of stroke, hypertension, and epilepsy influenced mild cognitive impairment (MCI) progression to dementia. Correlations between key risk factors and circulating neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), amyloid β protein (Aβ)40, and Aβ42/Aβ40 ratio suggest underlying mechanisms contributing to cognitive impairment.

DISCUSSION

The common and distinct risk factors across cognitive decline stages emphasize the need for tailored interventions. The correlations with blood biomarkers provide insights into potential management targets.

HIGHLIGHTS

From a large community-based cohort study on the residents in Chongqing, we have identified that mild cognitive impairment (MCI) and dementia share several common risk factors, including age, female gender, rural living, lower education levels, and a medical history of stroke. However, each condition also has its own unique risk factors. Several factors contribute to the progression of MCI into dementia including age, education levels, occupation, and a medical history of hypertension and epilepsy. We discover the correlations between the risk factors for dementia and blood biomarkers that indicate the presence of axonal damage, glial activation, and Aβ pathology.

Basic, Translational, and Clinical Research on Dementia

The global impact of dementia is an increasing area of concern and, according to the Alzheimer's Disease International (ADI) World Alzheimer Report 2021, up to 90% of dementia patients in low- and middle-income countries are not diagnosed [...].

Dietary vitamin A modifies the gut microbiota and intestinal tissue transcriptome, impacting intestinal permeability and the release of inflammatory factors, thereby influencing Aβ pathology

Background

Alzheimer's disease (AD) is an age-related neurodegenerative disorder with no effective interventions for curing or modifying its progression. However, emerging research suggests that vitamin A in the diet may play a role in both the prevention and treatment of AD, although the exact mechanisms are not fully understood.

Objectives

This study aims to investigate the dietary vitamin A modifies the gut microbiota and intestinal tissue transcriptome, impacting intestinal permeability and the release of inflammatory factors, thereby influencing Aβ pathology shedding light on its potential as a dietary intervention for AD prevention and treatment.

Methods

The APP/PS1-AD mouse model was employed and divided into three dietary groups: vitamin A-deficient (VAD), normal vitamin A (VAN), and vitamin A-supplemented (VAS) for a 12-week study. Neurobehavioral functions were assessed using the Morris Water Maze Test (MWM). Enzyme-linked immunosorbent assay (ELISA) was used to quantify levels of Diamine Oxidase (DAO), D-lactate, IL-6, IL-1β, and TNF-a cytokines. Serum vitamin A levels were analyzed via LC-MS/MS analysis. Immunohistochemical analysis and morphometry were performed to evaluate the deposition of Aβ in brain tissue. The gut microbiota of APP/PS1 mice was analyzed using 16S rRNA sequencing analysis. Additionally, transcriptomic analysis was conducted on intestinal tissue from APP/PS1 mice.

Results

No significant changes in food intake and body weight were observed among the groups. However, the VAD and VAS groups showed reduced food intake compared to the VAN group at various time points. In terms of cognitive function, the VAN group performed better in the Morris Water Maze Test, indicating superior learning and memory abilities. The VAD and VAS groups exhibited impaired performance, with the VAS group performing relatively better than the VAD group. Serum vitamin A concentrations differed significantly among the groups, with the VAS group having the highest concentration. Aβ levels were significantly higher in the VAD group compared to both the VAN and VAS groups. Microbial analysis revealed that the VAS and VAN groups had higher microbial diversity than the VAD group, with specific taxa characterizing each group. The VAN group was characterized by taxa such as Actinohacteriota and Desulfovibrionaceae, while the VAD group was characterized by Parabacteroides and Tannerellaceae. The VAS group showed similarities with both VAN and VAD groups, with taxa like Desulfobacterota and Desulfovibrionaceae being present. The VAD vs. VAS, VAD vs. VAN, and VAS vs. VAN comparisons identified 571, 313, and 243 differentially expressed genes, respectively, which associated with cellular and metabolic processes, and pathway analysis revealed enrichment in pathways related to chemical carcinogenesis, drug metabolism, glutathione metabolism, and immune-related processes. The VAD group exhibited higher levels of D-lactate, diamine oxidase, and inflammatory cytokines (TNF-a, IL-1β, IL-6) compared to the VAN and VAS groups.

Conclusion

Dietary vitamin A supplementation modulates the gut microbiota, intestinal permeability, inflammatory factors, and Aβ protein formation, offering insights into the pathogenesis of AD and potential therapeutic avenues for further exploration. This research highlights the intricate interplay between diet, gut microbiota, and neurodegenerative processes, emphasizing the importance of dietary interventions in managing AD-related pathologies.

The Metabolic Impact of Nonalcoholic Fatty Liver Disease on Cognitive Dysfunction: A Comprehensive Clinical and Pathophysiological Review

Nonalcoholic fatty liver disease (NAFLD) exponentially affects the global healthcare burden, and it is currently gaining increasing interest in relation to its potential impact on central nervous system (CNS) diseases, especially concerning cognitive deterioration and dementias. Overall, scientific research nowadays extends to different levels, exploring NAFLD's putative proinflammatory mechanism of such dysmetabolic conditions, spreading out from the liver to a multisystemic involvement. The aim of this review is to analyze the most recent scientific literature on cognitive involvement in NAFLD, as well as understand its underlying potential background processes, i.e., neuroinflammation, the role of microbiota in the brain-liver-gut axis, hyperammonemia neurotoxicity, insulin resistance, free fatty acids, and vitamins.

Impact of micronutrients and nutraceuticals on cognitive function and performance in Alzheimer's disease

Alzheimer's disease (AD) is a major global health problem today and is the most common form of dementia. AD is characterized by the formation of β-amyloid (Aβ) plaques and neurofibrillary clusters, leading to decreased brain acetylcholine levels in the brain. Another mechanism underlying the pathogenesis of AD is the abnormal phosphorylation of tau protein that accumulates at the level of neurofibrillary aggregates, and the areas most affected by this pathological process are usually the cholinergic neurons in cortical, subcortical, and hippocampal areas. These effects result in decreased cognitive function, brain atrophy, and neuronal death. Malnutrition and weight loss are the most frequent manifestations of AD, and these are also associated with greater cognitive decline. Several studies have confirmed that a balanced low-calorie diet and proper nutritional intake may be considered important factors in counteracting or slowing the progression of AD, whereas a high-fat or hypercholesterolemic diet predisposes to an increased risk of developing AD. Especially, fruits, vegetables, antioxidants, vitamins, polyunsaturated fatty acids, and micronutrients supplementation exert positive effects on aging-related changes in the brain due to their antioxidant, anti-inflammatory, and radical scavenging properties. The purpose of this review is to summarize some possible nutritional factors that may contribute to the progression or prevention of AD, understand the role that nutrition plays in the formation of Aβ plaques typical of this neurodegenerative disease, to identify some potential therapeutic strategies that may involve some natural compounds, in delaying the progression of the disease.

A Combinational Therapy for Preventing and Delaying the Onset of Alzheimer's Disease: A Focus on Probiotic and Vitamin Co-Supplementation

Alzheimer's disease is a progressive neurodegenerative disorder with a complex etiology, and effective interventions to prevent or delay its onset remain a global health challenge. In recent years, there has been growing interest in the potential role of probiotic and vitamin supplementation as complementary strategies for Alzheimer's disease prevention. This review paper explores the current scientific literature on the use of probiotics and vitamins, particularly vitamin A, D, E, K, and B-complex vitamins, in the context of Alzheimer's disease prevention and management. We delve into the mechanisms through which probiotics may modulate gut-brain interactions and neuroinflammation while vitamins play crucial roles in neuronal health and cognitive function. The paper also examines the collective impact of this combinational therapy on reducing the risk factors associated with Alzheimer's disease, such as oxidative stress, inflammation, and gut dysbiosis. By providing a comprehensive overview of the existing evidence and potential mechanisms, this review aims to shed light on the promise of probiotic and vitamin co-supplementation as a multifaceted approach to combat Alzheimer's disease, offering insights into possible avenues for future research and clinical application.

Large-Scale Population-Based Studies of Blood Metabolome and Brain Health

Metabolomics technologies enable the quantification of multiple metabolomic measures simultaneously, which provides novel insights into molecular aspects of human health and disease. In large-scale, population-based studies, blood is often the preferred biospecimen. Circulating metabolome may relate to brain health either by affecting or reflecting brain metabolism. Peripheral metabolites may act at or cross the blood-brain barrier and, subsequently, influence brain metabolism, or they may reflect brain metabolism if similar pathways are engaged. Peripheral metabolites may also include those penetrating the circulation from the brain, indicating, for example, brain damage. Most brain health-related metabolomics studies have been conducted in the context of neurodegenerative disorders and cognition, but some studies have also focused on neuroimaging markers of these disorders. Moreover, several metabolomics studies of neurodevelopmental disorders have been performed. Here, we provide a brief background on the types of blood metabolites commonly assessed, and we review the literature describing the relationships between human blood metabolome (n > 50 metabolites) and brain health reported in large-scale studies (n > 500 individuals).

Pathogenesis of Neurodegenerative Diseases and the Protective Role of Natural Bioactive Components

Neurodegenerative diseases are a serious problem throughout the world. There are several causes of neurodegenerative diseases; these include genetic predisposition, accumulation of misfolded proteins, oxidative stress, neuroinflammation, and excitotoxicity. Oxidative stress increases the production of reactive oxygen species (ROS) that advance lipid peroxidation, DNA damage, and neuroinflammation. The cellular antioxidant system (superoxide dismutase, catalase, peroxidase, and reduced glutathione) plays a crucial role in scavenging free radicals. An imbalance in the defensive actions of antioxidants and overproduction of ROS intensify neurodegeneration. The formation of misfolded proteins, glutamate toxicity, oxidative stress, and cytokine imbalance promote the pathogenesis of Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Antioxidants are now attractive molecules to fight against neurodegeneration. Certain vitamins (A, E, C) and polyphenolic compounds (flavonoids) show excellent antioxidant properties. Diet is the major source of antioxidants. However, diet medicinal herbs are also rich sources of numerous flavonoids. Antioxidants prevent ROS-mediated neuronal degeneration in post-oxidative stress conditions. The present review is focused on the pathogenesis of neurodegenerative diseases and the protective role of antioxidants. KEY TEACHING POINTSThis review shows that multiple factors are directly or indirectly associated with the pathogenesis of neurodegenerative diseases.Failure to cellular antioxidant capacity increases oxidative stress that intensifies neuroinflammation and disease progression.Different vitamins, carotenoids, and flavonoids, having antioxidant capacity, can be considered protective agents.

An in vitro model for vitamin A transport across the human blood-brain barrier

Vitamin A, supplied by the diet, is critical for brain health, but little is known about its delivery across the blood-brain barrier (BBB). Brain microvascular endothelial-like cells (BMECs) differentiated from human-derived induced pluripotent stem cells (iPSCs) form a tight barrier that recapitulates many of the properties of the human BBB. We paired iPSC-derived BMECs with recombinant vitamin A serum transport proteins, retinol-binding protein (RBP), and transthyretin (TTR), to create an in vitro model for the study of vitamin A (retinol) delivery across the human BBB. iPSC-derived BMECs display a strong barrier phenotype, express key vitamin A metabolism markers, and can be used for quantitative modeling of retinol accumulation and permeation. Manipulation of retinol, RBP, and TTR concentrations, and the use of mutant RBP and TTR, yielded novel insights into the patterns of retinol accumulation in, and permeation across, the BBB. The results described herein provide a platform for deeper exploration of the regulatory mechanisms of retinol trafficking to the human brain.

Roles of Oxidative Stress in Synaptic Dysfunction and Neuronal Cell Death in Alzheimer's Disease

Alzheimer's disease (AD) is a brain disorder that progressively undermines memory and thinking skills by affecting the hippocampus and entorhinal cortex. The main histopathological hallmarks of AD are the presence of abnormal protein aggregates (Aβ and tau), synaptic dysfunction, aberrant proteostasis, cytoskeletal abnormalities, altered energy homeostasis, DNA and RNA defects, inflammation, and neuronal cell death. However, oxidative stress or oxidative damage is also evident and commonly overlooked or considered a consequence of the advancement of dementia symptoms. The control or onset of oxidative stress is linked to the activity of the amyloid-β peptide, which may serve as both antioxidant and pro-oxidant molecules. Furthermore, oxidative stress is correlated with oxidative damage to proteins, nucleic acids, and lipids in vulnerable cell populations, which ultimately lead to neuronal death through different molecular mechanisms. By recognizing oxidative stress as an integral feature of AD, alternative therapeutic or preventive interventions are developed and tested as potential or complementary therapies for this devastating neurodegenerative disease.

Vitamin A metabolites inhibit ferroptosis

Vitamin A (retinol) is a lipid-soluble vitamin that acts as a precursor for several bioactive compounds, such as retinaldehyde (retinal) and isomers of retinoic acid. Retinol and all-trans-retinoic acid (atRA) penetrate the blood-brain barrier and are reported to be neuroprotective in several animal models. We characterised the impact of retinol and its metabolites, all-trans-retinal (atRAL) and atRA, on ferroptosis-a programmed cell death caused by iron-dependent phospholipid peroxidation. Ferroptosis was induced by erastin, buthionine sulfoximine or RSL3 in neuronal and non-neuronal cell lines. We found that retinol, atRAL and atRA inhibited ferroptosis with a potency superior to α-tocopherol, the canonical anti-ferroptotic vitamin. In contrast, we found that antagonism of endogenous retinol with anhydroretinol sensitises ferroptosis induced in neuronal and non-neuronal cell lines. Retinol and its metabolites atRAL and atRA directly interdict lipid radicals in ferroptosis since these compounds displayed radical trapping properties in a cell-free assay. Vitamin A, therefore, complements other anti-ferroptotic vitamins, E and K; metabolites of vitamin A, or agents that alter their levels, may be potential therapeutics for diseases where ferroptosis is implicated.

The association of vitamin A, zinc and copper levels with clinical symptoms in children with autism spectrum disorders in Jilin Province, China

BACKGROUND

This study evaluated vitamin A (VA), copper (Cu), and zinc (Zn) levels in the population with autism spectrum disorder (ASD) in Jilin Province, China. Furthermore, we examined their links to core symptoms and neurodevelopment, as well as gastrointestinal (GI) comorbidities and sleep disorders.

METHODS

This study included 181 children with autism and 205 typically developing (TD) children. The participants had not taken vitamin/mineral supplements in the prior three months. High-performance liquid chromatography was used to measure serum VA levels. By using inductively coupled plasma-mass spectrometry, Zn and Cu concentrations in plasma were determined. Importantly, the Childhood Autism Rating Scale, the Social Responsiveness Scale, and the Autism Behavior Checklist were used to measure core ASD symptoms. However, the Griffith Mental Development Scales-Chinese were used to measure neurodevelopment. GI comorbidities and sleep abnormalities were assessed with the 6 Item-Gastrointestinal Severity Index and Children's Sleep Habits Questionnaire, respectively. Children with ASD with GI issues were grouped according to severity (low GI severity and high GI severity groups).

RESULTS

(i) The difference in VA, Zn, Cu levels and the Zn/Cu ratio between ASD and TD children is small. But children with ASD had lower VA levels and Zn/Cu ratio, higher Cu levels than TD children. Cu levels in children with ASD were associated with the severity of core symptoms. (ii) Children with ASD were much more likely than their TD counterparts to suffer from GI comorbidities or sleep problems. Furthermore, it was observed that high GI severity was associated with lower levels of VA, whereas low GI severity was associated with higher levels of VA. (iii) The children with ASD who had both lower VA and lower Zn/Cu ratio had more severe scores on the Autism Behavior Checklist, but not on other measures.

CONCLUSION

Children with ASD had lower VA and Zn/Cu ratio, and higher Cu levels. Cu levels in children with ASD were weakly correlated with one subscale on social or self-help. ASD children with lower VA levels may face more serious GI comorbidities. Children with ASD combined VA-Zn/Cu lower had more severe core symptoms.

TRIAL REGISTRATION

Registration number: ChiCTR-OPC-17013502. Date of registration: 2017-11-23.

An in vitro model for vitamin A transport across the human blood-brain barrier

Vitamin A, supplied by the diet, is critical for brain health, but little is known about its delivery across the blood-brain barrier (BBB). Brain microvascular endothelial-like cells (BMECs) differentiated from human-derived induced pluripotent stem cells (iPSC) form a tight barrier that recapitulates many of the properties of the human BBB. We paired iPSC-derived BMECs with recombinant vitamin A serum transport proteins, retinol binding protein (RBP) and transthyretin (TTR), to create an in vitro model for the study of vitamin A (retinol) delivery across the human BBB. iPSC-derived BMECs display a strong barrier phenotype, express key vitamin A metabolism markers and can be used for quantitative modeling of retinol accumulation and permeation. Manipulation of retinol, RBP and TTR concentrations, and the use of mutant RBP and TTR, yielded novel insights into the patterns of retinol accumulation in, and permeation across, the BBB. The results described herein provide a platform for deeper exploration of the regulatory mechanisms of retinol trafficking to the human brain.

Revisiting the Role of Vitamins and Minerals in Alzheimer's Disease

Alzheimer's disease (AD) is the most common type of dementia that affects millions of individuals worldwide. It is an irreversible neurodegenerative disorder that is characterized by memory loss, impaired learning and thinking, and difficulty in performing regular daily activities. Despite nearly two decades of collective efforts to develop novel medications that can prevent or halt the disease progression, we remain faced with only a few options with limited effectiveness. There has been a recent growth of interest in the role of nutrition in brain health as we begin to gain a better understanding of what and how nutrients affect hormonal and neural actions that not only can lead to typical cardiovascular or metabolic diseases but also an array of neurological and psychiatric disorders. Vitamins and minerals, also known as micronutrients, are elements that are indispensable for functions including nutrient metabolism, immune surveillance, cell development, neurotransmission, and antioxidant and anti-inflammatory properties. In this review, we provide an overview on some of the most common vitamins and minerals and discuss what current studies have revealed on the link between these essential micronutrients and cognitive performance or AD.

Oxidative Stress and Natural Antioxidants: Back and Forth in the Neurological Mechanisms of Alzheimer's Disease

Alzheimer's disease (AD) is characterized by the progressive degeneration of neuronal cells. With the increase in aged population, there is a prevalence of irreversible neurodegenerative changes, causing a significant mental, social, and economic burden globally. The factors contributing to AD are multidimensional, highly complex, and not completely understood. However, it is widely known that aging, neuroinflammation, and excessive production of reactive oxygen species (ROS), along with other free radicals, substantially contribute to oxidative stress and cell death, which are inextricably linked. While oxidative stress is undeniably important in AD, limiting free radicals and ROS levels is an intriguing and potential strategy for deferring the process of neurodegeneration and alleviating associated symptoms. Therapeutic compounds from natural sources have recently become increasingly accepted and have been effectively studied for AD treatment. These phytocompounds are widely available and a multitude of holistic therapeutic efficiencies for treating AD owing to their antioxidant, anti-inflammatory, and biological activities. Some of these compounds also function by stimulating cholinergic neurotransmission, facilitating the suppression of beta-site amyloid precursor protein-cleaving enzyme 1, α-synuclein, and monoamine oxidase proteins, and deterring the occurrence of AD. Additionally, various phenolic, flavonoid, and terpenoid phytocompounds have been extensively described as potential palliative agents for AD progression. Preclinical studies have shown their involvement in modulating the cellular redox balance and minimizing ROS formation, displaying them as antioxidant agents with neuroprotective abilities. This review emphasizes the mechanistic role of natural products in the treatment of AD and discusses the various pathological hypotheses proposed for AD.

Micro- and Macronutrient Intake and Food Group Frequency Consumed by Subjects with Cognitive Impairment and Dementia in Latin America: A Systematic Review

BACKGROUND

Nutrition has relevant role in the pathogenesis of dementia. However, in Latin American Countries (LAC), it is unknown which type of diet the subjects with dementia and cognitive dysfunction have.

OBJECTIVE

The main purpose of this study was to determine micro- and macronutrients and food frequency intake among the LAC population with mild cognitive impairment (MCI) and dementia.

METHODS

A systematic review using PubMed, Cochrane, Lilacs, and Scielo databases. Energy intake as well as micro- and macronutrients intake were analyzed using a random-effect model and presented in a forest plot.

RESULTS

Nine articles were included, an estimated energy intake of 1598.47 kcal (95% CI 1351.07-1845.88) was obtained. A daily consumption of 73.64 g/day (95% CI 64.07-83.2) of protein; 262.17 g/day (95% CI 214.51-309.93) of carbohydrates, and 57.91 g/day (95% CI 49.16-66.66) of fats were reported. A micronutrients daily intake consumption of 201.35μg/day of vitamin B9 (95% CI 125.32-277.38); 5.61μg/day of vitamin B12 (95% CI 2.53-8.70), and 139.67 mg/day of vitamin C (95% CI 59.33-220.02). Mineral intake of 637.32 mg/day of calcium (95% CI 288.54-986.11) and 9 mg/day of iron (95% CI 2.28-15.71) was obtained. A low intake of fruits and vegetables was found.

CONCLUSION

Individuals with MCI and dementia from LAC have a nutritional deficiency characterized by a lower intake of fruits and vegetables, a high consumption of carbohydrates and protein, adequate fats intake and vitamins B12, vitamin C, and iron consumption, but a low intake of vitamin B9 and calcium.

Emerging roles of ER-resident selenoproteins in brain physiology and physiopathology

The brain has a very high oxygen consumption rate and is particularly sensitive to oxidative stress. It is also the last organ to suffer from a loss of selenium (Se) in case of deficiency. Se is a crucial trace element present in the form of selenocysteine, the 21st proteinogenic amino acid present in selenoproteins, an essential protein family in the brain that participates in redox signaling. Among the most abundant selenoproteins in the brain are glutathione peroxidase 4 (GPX4), which reduces lipid peroxides and prevents ferroptosis, and selenoproteins W, I, F, K, M, O and T. Remarkably, more than half of them are proteins present in the ER and recent studies have shown their involvement in the maintenance of ER homeostasis, glycoprotein folding and quality control, redox balance, ER stress response signaling pathways and Ca2+ homeostasis. However, their molecular functions remain mostly undetermined. The ER is a highly specialized organelle in neurons that maintains the physical continuity of axons over long distances through its continuous distribution from the cell body to the nerve terminals. Alteration of this continuity can lead to degeneration of distal axons and subsequent neuronal death. Elucidation of the function of ER-resident selenoproteins in neuronal pathophysiology may therefore become a new perspective for understanding the pathophysiology of neurological diseases. Here we summarize what is currently known about each of their molecular functions and their impact on the nervous system during development and stress.

Therapeutic insights elaborating the potential of retinoids in Alzheimer’s disease

Alzheimer’s disease (AD) is perceived with various pathophysiological characteristics such oxidative stress, senile plaques, neuroinflammation, altered neurotransmission immunological changes, neurodegenerative pathways, and age-linked alterations. A great deal of studies even now are carried out for comprehensive understanding of pathological processes of AD, though many agents are in clinical trials for the treatment of AD. Retinoids and retinoic acid receptors (RARs) are pertinent to such attributes of the disease. Retinoids support the proper functioning of the immunological pathways, and are very potent immunomodulators. The nervous system relies heavily on retinoic acid signaling. The disruption of retinoid signaling relates to several pathogenic mechanisms in the normal brain. Retinoids play critical functions in the neuronal organization, differentiation, and axonal growth in the normal functioning of the brain. Disturbed retinoic acid signaling causes inflammatory responses, mitochondrial impairment, oxidative stress, and neurodegeneration, leading to Alzheimer’s disease (AD) progression. Retinoids interfere with the production and release of neuroinflammatory chemokines and cytokines which are located to be activated in the pathogenesis of AD. Also, stimulating nuclear retinoid receptors reduces amyloid aggregation, lowers neurodegeneration, and thus restricts Alzheimer’s disease progression in preclinical studies. We outlined the physiology of retinoids in this review, focusing on their possible neuroprotective actions, which will aid in elucidating the critical function of such receptors in AD pathogenesis.

Better Bioactivity, Cerebral Metabolism and Pharmacokinetics of Natural Medicine and Its Advanced Version

Currently, many people are afflicted by cerebral diseases that cause dysfunction in the brain and perturb normal daily life of people. Cerebral diseases are greatly affected by cerebral metabolism, including the anabolism and catabolism of neurotransmitters, hormones, neurotrophic molecules and other brain-specific chemicals. Natural medicines (NMs) have the advantages of low cost and low toxicity. NMs are potential treatments for cerebral diseases due to their ability to regulate cerebral metabolism. However, most NMs have low bioavailability due to their low solubility/permeability. The study is to summarize the better bioactivity, cerebral metabolism and pharmacokinetics of NMs and its advanced version. This study sums up research articles on the NMs to treat brain diseases. NMs affect cerebral metabolism and the related mechanisms are revealed. Nanotechnologies are applied to deliver NMs. Appropriate delivery systems (exosomes, nanoparticles, liposomes, lipid polymer hybrid nanoparticles, nanoemulsions, protein conjugation and nanosuspensions, etc.) provide better pharmacological and pharmacokinetic characteristics of NMs. The structure-based metabolic reactions and enzyme-modulated catalytic reactions related to advanced versions of NMs alter the pharmacological activities of NMs.

Pathways explaining racial/ethnic disparities in incident all-cause and Alzheimer's disease dementia among older US men and women

Introduction

Racial disparities in Alzheimer's disease (AD) and all-cause dementia (DEMENTIA) incidence may exist differentially among men and women, with unknown mechanisms.

Methods

A retrospective cohort study examining all-cause and AD dementia incidence was conducted linking Third National Health and Nutrition Examination Survey (NHANES III) to Centers for Medicare & Medicaid Services Medicare data over ≤26 years of follow-up (1988 to 2014). Cox regression and generalized structural equation models (GSEMs) were constructed among men and women ≥60 years of age at baseline (N = 4592). Outcomes included onset ages of all-cause and AD dementia, whereas the main exposures were race/ethnicity contrasts (RACE_ETHN). Potential mediators) included socio-economic status (SES), lifestyle factors (dietary quality [DIET] nutritional biomarkers [NUTR], physical activity [PA], social support [SS], alcohol [ALCOHOL], poor health [or HEALTH], poor cognitive performance [or COGN]. In addition to RACE_ETHN, the following were exogenous covariates in the GSEM and potential confounders in Cox models: age, sex, urban-rural, household size, and marital status.

Results

Non-Hispanic Black (NHB) women had a higher risk of DEMENTIA versus non-Hispanic White (NHW) women in GSEM, consistent with Cox models (age-adjusted model: hazard ratio [HR] = 1.34, 95% confidence interval [CI]: 1.10 to 1.61). The total effect of this RACE_ETHN contrast in women was explained by four main pathways: (1) RACE_ETHN→ poor cognitive performance (COGN, +) → DEMENTIA (+); (2) RACE_ETHN → SES (-) → COGN (-) → DEMENTIA (+); (3) RACE_ETHN → SES (-) → physical activity (PA, +) → COGN (-) → DEMENTIA (+); and (4) RACE_ETHN → SES (-) → DIET (+) → COGN (-) → DEMENTIA (+). A reduced AD risk in Mexican American (MA) women versus NHW women upon adjustment for SES and downstream factors (HR = 0.53, 95% CI: 0.35 to 0.80). For the non-White versus NHW contrast in incident DEMENTIA, pathways involved lower SES, directly increasing cognitive deficits (or indirectly through lifestyle factors), which then directly increases DEMENTIA .

Discussion

Socioeconomic and lifestyle factors explaining disparities between NHB and NHW in dementia onset among women are important to consider for future observational and intervention studies.

Brain-derived neurotrophic factor in Alzheimer's disease and its pharmaceutical potential

Synaptic abnormalities are a cardinal feature of Alzheimer's disease (AD) that are known to arise as the disease progresses. A growing body of evidence suggests that pathological alterations to neuronal circuits and synapses may provide a mechanistic link between amyloid β (Aβ) and tau pathology and thus may serve as an obligatory relay of the cognitive impairment in AD. Brain-derived neurotrophic factors (BDNFs) play an important role in maintaining synaptic plasticity in learning and memory. Considering AD as a synaptic disorder, BDNF has attracted increasing attention as a potential diagnostic biomarker and a therapeutical molecule for AD. Although depletion of BDNF has been linked with Aβ accumulation, tau phosphorylation, neuroinflammation and neuronal apoptosis, the exact mechanisms underlying the effect of impaired BDNF signaling on AD are still unknown. Here, we present an overview of how BDNF genomic structure is connected to factors that regulate BDNF signaling. We then discuss the role of BDNF in AD and the potential of BDNF-targeting therapeutics for AD.

Vitamin A Deficiency Exacerbates Gut Microbiota Dysbiosis and Cognitive Deficits in Amyloid Precursor Protein/Presenilin 1 Transgenic Mice

Vitamin A deficiency (VAD) plays an essential role in the pathogenesis of Alzheimer’s disease (AD). However, the specific mechanism by which VAD aggravates cognitive impairment is still unknown. At the intersection of microbiology and neuroscience, the gut-brain axis is undoubtedly contributing to the formation and function of neurological systems, but most of the previous studies have ignored the influence of gut microbiota on the cognitive function in VAD. Therefore, we assessed the effect of VAD on AD pathology and the decline of cognitive function in AD model mice and determined the role played by the intestinal microbiota in the process. Twenty 8-week-old male C57BL/6J amyloid precursor protein/presenilin 1 (APP/PS1) transgenic mice were randomly assigned to either a vitamin A normal (VAN) or VAD diet for 45 weeks. Our results show that VAD aggravated the behavioral learning and memory deficits, reduced the retinol concentration in the liver and the serum, decreased the transcription of vitamin A (VA)-related receptors and VA-related enzymes in the cortex, increased amyloid-β peptides (Aβ40 and Aβ42) in the brain and gut, upregulate the translation of beta-site APP-cleaving enzyme 1 (BACE1) and phosphorylated Tau in the cortex, and downregulate the expression of brain-derived neurotrophic factor (BDNF) and γ-aminobutyric acid (GABA) receptors in the cortex. In addition, VAD altered the composition and functionality of the fecal microbiota as exemplified by a decreased abundance of Lactobacillus and significantly different α- and β-diversity. Of note, the functional metagenomic prediction (PICRUSt analysis) indicated that GABAergic synapse and retinol metabolism decreased remarkably after VAD intervention, which was in line with the decreased expression of GABA receptors and the decreased liver and serum retinol. In summary, the present study provided valuable facts that VAD exacerbated the morphological, histopathological, molecular biological, microbiological, and behavioral impairment in the APP/PS1 transgenic mice, and the intestinal microbiota may play a key mediator role in this mechanism.

Role of Retinoid X Receptors (RXRs) and dietary vitamin A in Alzheimer's disease: Evidence from clinicopathological and preclinical studies

BACKGROUND

Vitamin A (VitA), via its active metabolite retinoic acid (RA), is critical for the maintenance of memory function with advancing age. Although its role in Alzheimer's disease (AD) is not well understood, data suggest that impaired brain VitA signaling is associated with the accumulation of β-amyloid peptides (Aβ), and could thus contribute to the onset of AD.

METHODS

We evaluated the protective action of a six-month-long dietary VitA-supplementation (20 IU/g), starting at 8 months of age, on the memory and the neuropathology of the 3xTg-AD mouse model of AD (n = 11-14/group; including 4-6 females and 7-8 males). We also measured protein levels of Retinoic Acid Receptor β (RARβ) and Retinoid X Receptor γ (RXRγ) in homogenates from the inferior parietal cortex of 60 participants of the Religious Orders study (ROS) divided in three groups: no cognitive impairment (NCI) (n = 20), mild cognitive impairment (MCI) (n = 20) and AD (n = 20).

RESULTS

The VitA-enriched diet preserved spatial memory of 3xTg-AD mice in the Y maze. VitA-supplementation affected hippocampal RXR expression in an opposite way according to sex by tending to increase in males and decrease in females their mRNA expression. VitA-enriched diet also reduced the amount of hippocampal Aβ₄₀ and Aβ₄₂, as well as the phosphorylation of tau protein at sites Ser396/Ser404 (PHF-1) in males. VitA-supplementation had no effect on tau phosphorylation in females but worsened their hippocampal Aβ load. However, the expression of Rxr-β in the hippocampus was negatively correlated with the amount of both soluble and insoluble Aβ in both males and females. Western immunoblotting in the human cortical samples of the ROS study did not reveal differences in RARβ levels. However, it evidenced a switch from a 60-kDa-RXRγ to a 55-kDa-RXRγ in AD, correlating with ante mortem cognitive decline and the accumulation of neuritic plaques in the brain cortex.

CONCLUSION

Our data suggest that (i) an altered expression of RXRs receptors is a contributor to β-amyloid pathology in both humans and 3xTg-AD mice, (ii) a chronic exposure of 3xTg-AD mice to a VitA-enriched diet may be protective in males, but not in females.

Medicinal herbs and nutritional supplements for dementia therapy: potential therapeutic targets and clinical evidence

Spices and herbs have been used for medicinal purposes for centuries. Also, in the last decades, the use of different nutritional supplements has been implemented to treat all kinds of diseases, including those that present an alteration in cognitive functioning. Dementia is a clinical syndrome in which a person's mental and cognitive capacities gradually decline. As the disease progresses, the person's autonomy diminishes. As there is not an effective treatment to prevent progressive deterioration in many of these pathologies, nutritional interventions have been, and still are, one of the most widely explored therapeutic possibilities. In this review, we have discussed a great number of potentially interesting plants, nutritional derivatives and probiotics for the treatment of dementia around the world. Their action mechanisms generally involve neuroprotective effects via anti-inflammatory, antioxidant, anti-apoptotic, b-amyloid and tau anti-aggregate actions; brain blood flow improvement, and effects on synaptic cholinergic and dopaminergic neurotransmission, which may optimize cognitive performance in patients with cognitive impairment. As for their efficacy in patients with cognitive impairment and/or dementias, evidence is still scarce and/or their outcomes are controversial. We consider that many of these substances have promising therapeutic properties. Therefore, the scientific community has to continue with a more complete research focused on both identifying possible action mechanisms and carrying out clinical trials, preferably randomized double-blind ones, with a greater number of patients, a long-term follow-up, dose standardization and the use of current diagnosis criteria.

Circulating Plasma Metabolites and Cognitive Function in a Puerto Rican Cohort

BACKGROUND

Minorities, including mainland Puerto Ricans, are impacted disproportionally by Alzheimer's disease (AD), dementia, and cognitive decline. Studying blood metabolomics in this population has the potential to probe the biological underpinnings of this health disparity.

OBJECTIVE

We performed a comprehensive analysis of circulating plasma metabolites in relation to cognitive function in 736 participants from the Boston Puerto Rican Health Study (BPRHS) who underwent untargeted mass-spectrometry based metabolomics analysis and had undergone a battery of in-person cognitive testing at baseline.

METHODS

After relevant exclusions, 621 metabolites were examined. We used multivariable regression, adjusted for age, sex, education, apolipoprotein E genotype, smoking, and Mediterranean dietary pattern, to identify metabolites related to global cognitive function in our cohort. LASSO machine learning was used in a complementary analysis to identify metabolites that could discriminate good from poor extremes of cognition. We also conducted sensitivity analyses: restricted to participants without diabetes, and to participants with good adherence to Mediterranean diet.

RESULTS

Of 621 metabolites, FDR corrected (p < 0.05) multivariable linear regression identified 3 metabolites positively, and 10 negatively, associated with cognitive function in the BPRHS. In a combination of FDR-corrected linear regression, logistic regression regularized via LASSO, and sensitivity analyses restricted to participants without diabetes, and with good adherence to the Mediterranean diet, β-cryptoxanthin plasma concentration was consistently associated with better cognitive function and N-acetylisoleucine and tyramine O-sulfate concentrations were consistently associated with worse cognitive function.

CONCLUSION

This untargeted metabolomics study identified potential biomarkers for cognitive function in a cohort of Puerto Rican older adults.

In Pursuit of Healthy Aging: Effects of Nutrition on Brain Function

Consuming a balanced, nutritious diet is important for maintaining health, especially as individuals age. Several studies suggest that consuming a diet rich in antioxidants and anti-inflammatory components such as those found in fruits, nuts, vegetables, and fish may reduce age-related cognitive decline and the risk of developing various neurodegenerative diseases. Numerous studies have been published over the last decade focusing on nutrition and how this impacts health. The main objective of the current article is to review the data linking the role of diet and nutrition with aging and age-related cognitive decline. Specifically, we discuss the roles of micronutrients and macronutrients and provide an overview of how the gut microbiota-gut-brain axis and nutrition impact brain function in general and cognitive processes in particular during aging. We propose that dietary interventions designed to optimize the levels of macro and micronutrients and maximize the functioning of the microbiota-gut-brain axis can be of therapeutic value for improving cognitive functioning, particularly during aging.

Personalized treatment interventions: nonpharmacological and natural treatment strategies in Alzheimer's disease

Introduction: Alzheimer's disease (AD) is a slow, irreversible, progressive, complex, and fatal neurodegenerative disorder. Available pharmacological treatment, known for almost two decades, does not cure the disease, but only alleviates the symptoms, with various efficacy and different side effects. Therefore, there is an unmet need to find other person-centered or personalized approaches to treat AD.Areas covered: This article describes the application of precision medicine-like approaches utilizing nonpharmacological treatment strategies and the use of natural products in personalized care for patients with AD.Expert opinion: Due to the heterogeneity of disease symptoms, somatic conditions, and patient preferences, there is definitely no "one size fits all" intervention. Therefore, individualized treatment choice is based on dementia stage, medical and psychiatric comorbidity, leading symptoms, patient preferences, and remaining capacity of the patient. In the absence of disease-modifying agents, a patient-centered, multidisciplinary team approach appears to be the best option to alleviate the heavy symptomatic burden in this unfortunate population. Hence, appropriate interventions can be offered along the AD continuum, while a better understanding of personal characteristics might help in establishing optimal individualized treatment, as well as its duration and intensity, to deliver interventions in the most effective ways.

The Association Between Folate and Alzheimer's Disease: A Systematic Review and Meta-Analysis

Alzheimer's disease (AD) is the most common type of neurodegenerative disease leading to dementia in the elderly. Increasing evidence indicates that folate plays an important role in the pathogenesis of AD. To investigate the role of folate deficiency/possible deficiency in the risk of AD and the benefical effect of sufficient folate intake on the prevention of AD, a systematic review and meta-analysis were performed. The Web of Science, PubMed, CENTRAL, EBSCO, CNKI, CQVIP, and Wanfang databases were searched. The analysis of cross-sectional studies showed that the standardized mean difference (SMD) was −0.60 (95% confidence interval (CI): −0.65, −0.55), indicating that plasma/serum folate level is lower in AD patients than that in controls. Moreover, the combined odds ratio (OR) of case-control studies was 0.96 (95% CI: 0.93, 0.99), while the combined ORs were 0.86 (95% CI: 0.46, 1.26) and 1.94 (95% CI: 1.02, 2.86) in populations with normal levels of folate (≥13.5 nmol/L) and folate deficiency/possible deficiency (<13.5 nmol/L), respectively. In addition, the risk ratio (RR) of the cohort studies was 1.88 (95% CI: 1.20, 2.57) in populations with folate deficiency/possible deficiency. Furthermore, when the intake of folate was equal to or higher than the recommended daily allowance, the combined RR and hazard ratio (HR) were 0.44 (95% CI: 0.18, 0.71) and 0.76 (95% CI: 0.52, 0.99), respectively. These results indicate that folate deficiency/possible deficiency increases the risk for AD, while sufficient intake of folate is a protective factor against AD.

Serum retinol levels are associated with cognitive function among community-dwelling older Mexican adults

BACKGROUND

Vitamin A (VA) provides neuroprotection against oxidative stress and brain inflammation. VA deficiency (VAD) increases the risk of neurodegeneration in animal models, but results are inconclusive in humans: particularly in the older adult (OA) population which is at higher risk for micronutrient deficiencies and cognitive impairment.

OBJECTIVE

To estimate the association between serum retinol levels and cognitive function (CF) in older Mexican adults.

METHODS

Cross-sectional study with 803 adults aged ≥60 years with fasting blood sample from the southern region of Mexico, collected in summer of 2015. Low serum retinol (LSR) was defined if serum retinol ≤20 µg/dl. CF was evaluated using Semantic Verbal Fluency Test (SVFT). Mild cognitive impairment (MCI) was defined using normative values for SVFT. Linear and logistic regression models were used to estimate the association of LSR with CF and MCI, respectively.

RESULTS

Prevalence of MCI was 9.35% and LSR 3.36%. OA with LSR evoked less words in the SVFT (β = -2.8, CI95% -4.6, -0.9) and had higher probability of MCI (OR =  2.7, CI95% 0.9, 7.7). Associations remained significant when considered IL-6.

CONCLUSION

Frequency of LSR in older Mexican adults was low, but strongly associated with MCI. This result suggests that VA plays a role in maintaining CF in the elderly population. Since VAD is a reversible condition, further studies are needed in order to identify the main causes of LSR and prevent MCI in populations which are at higher risk for malnutrition.Trial registration: ClinicalTrials.gov identifier: NCT04820465.

Consumption of vitamin A-deficient diet elevates endoplasmic reticulum stress marker and suppresses high fructose-induced orexigenic gene expression in the brain of male Wistar rats

OBJECTIVE

Here, we assessed the impact of vitamin A deficiency (both alone and in combination with fructose) on the retinol status, phospholipids fatty acid composition and pathways associated with the endoplasmic reticulum (ER) stress and energy homeostasis of the brain. For this purpose, weanling male Wistar rats were divided into four groups consisting of 8 rats each, except 16 for the second group and they received one of the following diets; control, vitamin A-deficient (VAD), high fructose (HFr) and HFr with VAD for 16 weeks, except half of the VAD diet-fed rats, were shifted to HFr diet, after 8 weeks period.

RESULTS

The retinol content of the whole brain remained comparable across the groups, despite a significant reduction in the plasma at the end of VAD diet feeding. However, it suppressed the HFr-induced neuropeptide Y and agouti-related peptide, while rescuing the leptin receptor mRNA. Among ER stress markers, CCAAT/Enhancer-binding protein homologues protein levels were elevated significantly in the VAD diet-fed group. Further, the long-chain polyunsaturated fatty acid levels showed an increase in the brain phospholipids across the experimental groups, compared to that of the control.

CONCLUSION

Vitamin A deficiency causes ER stress in the brain, and retinol seems to play a regulatory role in the fructose-mediated transcriptional regulation of the genes involved in energy homeostasis.

Pouteria sapota (Red Mamey Fruit): Chemistry and Biological Activity of Carotenoids

BACKGROUND

Red mamey fruit known as P. sapota, comes from trees found in Mesoamerica and Asia. This fruit is considered a nutraceutical food due to it's a food and has multiple beneficial health including anti-amyloidogenic activity and potential anti-tumorigenic property. Red mamey fruit contain a variety of carotenoids including novel ketocarotenoids such as sapotexanthin and cryptocapsin. A ketocarotenoid is a chemical compound with a carbonyl group present in the β-ring or in the double bond chain of a carotenoid. In red mamey, the 3'-deoxy-k-end group in sapotexanthin has proved to be an important pro-vitamin A source, which is essential for maintaining a healthy vision and cognitive processes.

OBJECTIVE

Summarize the chemistry and biological activity of the studied carotenoids present in this fruit until now.

METHOD

An exhaustive extraction is the most usual methodology to isolate and thoroughly characterize the carotenoids present in this fruit. High performance liquid chromatography is used to determine the profile of total carotenoid and its purity. Atmospheric pressure chemical ionization is used to determine the molecular weight of carotenoid. Nuclear magnetic resonance is used to determine the structure of carotenoids.

RESULT

For each 100 g of fresh weight, 0.12 mg of total carotenoid from this fruit can be obtained. Out of the more than 47 reported carotenoids in red mamey, only 34 have a detailed characterization.

CONCLUSION

it is important to continue studying the chemical composition and biological activity of this unique tropical fruit with commercial and nutritional value.

Vitamin A deficiency increases the risk of gastrointestinal comorbidity and exacerbates core symptoms in children with autism spectrum disorder

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, and many individuals with ASD have gastrointestinal (GI) comorbidities. Vitamin A (VA) is an essential micronutrient that plays an important role in brain development and GI function.

METHODS

A total of 323 children with ASD and 180 control children were enrolled in this study. Symptoms of ASD were assessed with the Child Autism Rating Scale (CARS), the Social Responsiveness Scale (SRS), and the Autism Behavior Checklist (ABC). Caregivers of the children completed questionnaires about GI symptoms. Serum retinol levels were detected with high-performance liquid chromatography (HPLC).

RESULTS

Children with ASD and with GI comorbidity and constipation had considerably lower serum VA levels than autistic children without these symptoms. VA level was associated with CARS, SRS, and ABC scores, whereas GI symptoms were associated some SRS and ABC scores. The interaction of VAD and GI symptoms appeared to aggravate some of the core symptoms of children with ASD.

CONCLUSIONS

VAD exacerbates core symptoms in children with ASD, and ASD children with GI comorbidities also have more serious core symptoms than ASD children without GI comorbidities. VAD comorbid with GI symptoms aggravates autistic children's core symptoms.

IMPACT

VAD exacerbates core symptoms in children with ASD. ASD children with GI comorbidities have more serious core symptoms than ASD children without GI comorbidities. VAD comorbid with GI symptoms aggravates autistic children's core symptoms. We speculate that VAD might be related to a subtype of ASD that involves GI comorbidities. We believe that our findings will be of fundamental importance to the scientific community.

Type II nuclear receptors with potential role in Alzheimer disease

Nuclear receptors are ligand-activated transcription factors that can modulated cellular processes involved in the development, homeostasis, cell proliferation, metabolism, and reproduction through the control of the specific genetic and molecular program. In the central nervous system, they are key regulators of neural stem cell fate decisions and can modulate the physiology of different brain cells. Over the past decades, a large body of evidence has supported that nuclear receptors are potential therapeutic targets for the treatment of neurodegenerative disorders such as Alzheimer's disease, the most common dementia worldwide, and the main cause of disability in later life. This disease is characterized by the progressive accumulation of amyloid-beta peptides and hyperphosphorylated tau protein that can explain alterations in synaptic transmission and plasticity; loss of dendritic spines; increased in reactive microglia and inflammation; reduction of neuronal stem cells number; myelin and vascular alterations that finally leads to increased neuronal death. Here, we present a review of type II no steroidal nuclear receptors that form obligatory heterodimers with the Retinoid X Receptor (RXR) and its potential in the therapeutic of AD. Activation of type II nuclear receptor by synthetic agonist leads to transcriptional regulation of specific genes that acts counteracting against the detrimental effects of amyloid-beta peptides and hyperphosphorylated tau in neuronal cells recovering the functionality of the synapses. But also, activation of type II nuclear receptor leads to modifications in APP metabolism, repression of inflammatory cascade and inductors of the generation of neuronal stem cells and progenitor cells supporting its potential therapeutics role for Alzheimer's disease.

Vitamins: a nutritional intervention to modulate the Alzheimer's disease progression

Background: Alzheimer's disease is known as one of the fastest growing lethal diseases worldwide where we have limited and undesired ways for regulating its pathological progress. Now-a-days, nutritional compounds have been using to treat several brain disorders and one of them; vitamins were strongly reported to combat cognition and memory deterioration in neurodegenerative diseases including Alzheimer's disease. Objective: Here, the author tried to find the precise physiological roles, status, and worth of vitamins in the brain and how exactly these nutrients modulate progression of Alzheimer's disease. Results & Discussion: After a comprehensive and systematic literature review, the author reports that vitamins have various targets in Alzheimer's disease pathogenesis by which they act to avert the neuronal dysfunction in the disease. Several Alzheimer's disease-associated neurological deficits have reported regulating by vitamin intake but the beneficial effects identified mostly in combinatorial and long-term studies. Conclusion: In this way, the author suggests that it might be better to test vitamins with other components over single vitamin approach for a compatible and synergistic effect as well as using a combination of vitamin with other compounds can target multiple pathways. This strategy may help in deteriorating memory dysfunction and cognition impairment in Alzheimer's disease pathophysiology.Abbreviations: APOE: apolipoprotein E; APP: amyloid precursor protein; ATP: adenosine triphosphate; Aβ- β-amyloid; cGMP: cyclic guanine monophosphate; CNS: central nervous system; DNA: deoxyribonucleic acid; IU: international units; RA: retinoic acid; RAR: retinoic acid receptor; RNA: ribonucleic acid; ROS: reactive oxygen species; tHcy: total homocysteine; α: alpha; β: beta; γ: gama; ε: epsilon; g: gram; µ: micron; mg: milligram; ⬆: increased,⬇: decreased.

Vitamin A and Retinoic Acid in Cognition and Cognitive Disease

The history of vitamin A goes back over one hundred years, but our realization of its importance for the brain and cognition is much more recent. The brain is more efficient than other target tissues at converting vitamin A to retinoic acid (RA), which activates retinoic acid receptors (RARs). RARs regulate transcription, but their function in the cytoplasm to control nongenomic actions is also crucial. Controlled synthesis of RA is essential for regulating synaptic plasticity in regions of the brain involved in learning and memory, such as the hippocampus. Vitamin A deficiency results in a deterioration of these functions, and failure of RA signaling is perhaps associated with normal cognitive decline with age as well as with Alzheimer's disease. Further, several psychiatric and developmental disorders that disrupt cognition are also linked with vitamin A and point to their possible treatment with vitamin A or RA.

Retinoic Acid and the Gut Microbiota in Alzheimer's Disease: Fighting Back-to-Back?

BACKGROUND

There is growing evidence that the gut microbiota may play an important role in neurodegenerative diseases such as Alzheimer's disease. However, how these commensals influence disease risk and progression still has to be deciphered.

OBJECTIVE

The objective of this review was to summarize current knowledge on the interplay between gut microbiota and retinoic acid. The latter one represents one of the important micronutrients, which have been correlated to Alzheimer's disease and are used in initial therapeutic intervention studies.

METHODS

A selective overview of the literature is given with the focus on the function of retinoic acid in the healthy and diseased brain, its metabolism in the gut, and the potential influence that the bioactive ligand may have on microbiota, gut physiology and, Alzheimer's disease.

RESULTS

Retinoic acid can influence neuronal functionality by means of plasticity but also by neurogenesis and modulating proteostasis. Impaired retinoid-signaling, therefore, might contribute to the development of diseases in the brain. Despite its rather direct impact, retinoic acid also influences other organ systems such as gut by regulating the residing immune cells but also factors such as permeability or commensal microbiota. These in turn can also interfere with retinoid-metabolism and via the gutbrain- axis furthermore with Alzheimer's disease pathology within the brain.

CONCLUSION

Potentially, it is yet too early to conclude from the few reports on changed microbiota in Alzheimer's disease to a dysfunctional role in retinoid-signaling. However, there are several routes how microbial commensals might affect and might be affected by vitamin A and its derivatives.

Dietary Wheat Amylase Trypsin Inhibitors Impact Alzheimer's Disease Pathology in 5xFAD Model Mice

Wheat amylase trypsin inhibitors (ATIs) represent a common dietary protein component of gluten-containing cereals (wheat, rye, and barley). They act as toll-like receptor 4 ligands, and are largely resistant to intestinal proteases, eliciting a mild inflammatory response within the intestine after oral ingestion. Importantly, nutritional ATIs exacerbated inflammatory bowel disease and features of fatty liver disease and the metabolic syndrome in mice. For Alzheimer’s disease (AD), both inflammation and altered insulin resistance are major contributing factors, impacting onset as well as progression of this devastating brain disorder in patients. In this study, we evaluated the impact of dietary ATIs on a well-known rodent model of AD (5xFAD). We assessed metabolic, behavioral, inflammatory, and microbial changes in mice consuming different dietary regimes with and without ATIs, consumed ad libitum for eight weeks. We demonstrate that ATIs, with or without a gluten matrix, had an impact on the metabolism and gut microbiota of 5xFAD mice, aggravating pathological hallmarks of AD. If these findings can be translated to patients, an ATI-depleted diet might offer an alternative therapeutic option for AD and warrants clinical intervention studies.

Vitamin A deficiency exacerbates extrinsic atopic dermatitis development by potentiating type 2 helper T cell-type inflammation and mast cell activation

BACKGROUND

Vitamin A deficiency (VAD) has been hypothesized to play a role in the pathophysiology of atopic dermatitis (AD).

OBJECTIVE

We sought to verify whether VAD can exacerbate AD development, and explore the possible pathophysiologic mechanism.

METHODS

We detected serum vitamin A (VA) concentration in different phenotypes of AD infants (intrinsic AD, iAD and extrinsic AD, eAD), and established ovalbumin (OVA) percutaneous sensitized AD model and passive cutaneous anaphylaxis (PCA) model on VAD and vitamin A supplementation (VAS) model in wild-type mice (C57BL/6) and established AD model on both normal VA (VAN) and VAD feeding mast cell deficiency mice (ckit^w-sh/w-sh ).

RESULTS

The average serum VA concentration of eAD was significantly lower than that of iAD, as well as healthy controls. In OVA-induced C57BL/6 mouse AD model, compared with VAN group, VAD mice manifested significantly more mast cells accumulation in the skin lesions, more severe Th2-mediated inflammation, including higher serum IgG1 and IgE levels, more IL-4, IL-13 mRNA expression in OVA-sensitized skin, and lower Th1 immune response, including lower serum IgG2a and IFN-γ mRNA expression in the skin. But there was no significant difference in the expression of IL-17 mRNA between OVA-treated skin of VAN and VAD mice. However, in OVA-induced ckit^w-sh/w-sh mouse AD model, we did not find any significant differences in the above measurements between VAD and VAN group. In PCA model, VAD mice showed remarkable more blue dye leakage than that in VAN mice. Compared with VAD group, the above-mentioned inflammatory measurements in VAS group and VAN group were similar in OVA-induced AD model mice.

CONCLUSIONS AND CLINICAL RELEVANCE

VAD can exacerbate extrinsic AD by augmenting Th2-mediated inflammation and mast cell activation. Therapeutic VAS can rescue VAD-aggravated eAD. It may provide a new strategy for future prevention or treatment of atopic dermatitis.

Central and Peripheral Metabolic Defects Contribute to the Pathogenesis of Alzheimer's Disease: Targeting Mitochondria for Diagnosis and Prevention

Significance: Epidemiological studies indicate that metabolic disorders are associated with an increased risk for Alzheimer's disease (AD). Metabolic remodeling occurs in the central nervous system (CNS) and periphery, even in the early stages of AD. Mitochondrial dysfunction has been widely accepted as a molecular mechanism underlying metabolic disorders. Therefore, focusing on early metabolic changes, especially from the perspective of mitochondria, could be of interest for early AD diagnosis and intervention. Recent Advances: We and others have identified that the levels of several metabolites are fluctuated in the periphery before their accumulation in the CNS, which plays an important role in the pathogenesis of AD. Mitochondrial remodeling is likely one of the earliest signs of AD, linking nutritional imbalance to cognitive deficits. Notably, by improving mitochondrial function, mitochondrial nutrients efficiently rescue cellular metabolic dysfunction in the CNS and periphery in individuals with AD. Critical Issues: Peripheral metabolic disorders should be intensively explored and evaluated for the early diagnosis of AD. The circulating metabolites derived from mitochondrial remodeling represent novel potential diagnostic biomarkers for AD that are more readily detected than CNS-oriented biomarkers. Moreover, mitochondrial nutrients provide a promising approach to preventing and delaying AD progression. Future Directions: Abnormal mitochondrial metabolism in the CNS and periphery is involved in AD pathogenesis. More clinical studies provide evidence for the suitability and reliability of circulating metabolites and cytokines for the early diagnosis of AD. Targeting mitochondria to rewire cellular metabolism is a promising approach to preventing AD and ameliorating AD-related metabolic disorders.

The challenges of the COVID-19 pandemic: Approaches for the elderly and those with Alzheimer's disease

Coronavirus disease 2019 (COVID-19) is an infectious disease that since its outbreak in December 2019 has become a global pandemic. COVID-19 is caused by the previously unknown coronavirus SARS-CoV-2. The elderly are the most vulnerable to COVID-19, and have the highest mortality of the afflicted. Similar patterns have been observed in epidemics and pandemics throughout the 20th and the beginning of the 21st centuries. In this article, we review some unique challenges the elderly and people with Alzheimer's disease face during the COVID-19 pandemic and suggest approaches that could be taken from healthcare and social approaches to better handle this pandemic.

Gesell Developmental Schedules scores and the relevant factors in children with Down syndrome

Background Down syndrome (DS) is a common chromosomal disease resulting in neurodegeneration. Cognitive competence has been assessed among adults with DS using various methods because DS patients have a tendency to develop Alzheimer's disease (AD) after middle age. However, research describing cognitive assessments in DS children is not as many as in DS adults, let alone with regard to performed analyses to determine factors that predict cognitive assessments. In this study, we evaluated the Gesell Developmental Schedules (GDS) scores and their associations with the relevant biochemical indicators and demographic factors in DS children. Methods All the subjects underwent GDS testing. The plasma amyloid-β (Aβ) peptide and serum vitamin A (VA) values were measured with enzyme-linked immunosorbent assay and high-performance liquid chromatography, and in the meanwhile, the demographic information of the subjects was collected. Results Forty-six DS children were recruited for this study. The GDS scores of children with DS were lower than those in children without DS. The plasma Aβ40 and Aβ42 levels were negatively associated with the GDS scores. Moreover, the GDS scores of the non-VA deficiency (NVAD) group were significantly higher than those of the VA deficiency (VAD) group. Certain demographic characteristics, such as the paternal labor intensity and paternal educational status, were relevant factors with regard to the GDS scores of the DS children. Conclusions This study determined that DS children exhibited abnormal GDS scores which indicated developmental delay of children with DS; the levels of plasma Aβ40, Aβ42 and serum VA were influential biochemical indicators and the paternal labor intensity and educational status were related demographic factors.

A presenilin-1 mutation causes Alzheimer disease without affecting Notch signaling

Presenilin-1 (PSEN1) is the catalytic subunit of the γ-secretase complex, and pathogenic mutations in the PSEN1 gene account for the majority cases of familial AD (FAD). FAD-associated mutant PSEN1 proteins have been shown to affect APP processing and Aβ generation and inhibit Notch1 cleavage and Notch signaling. In this report, we found that a PSEN1 mutation (S169del) altered APP processing and Aβ generation, and promoted neuritic plaque formation as well as learning and memory deficits in AD model mice. However, this mutation did not affect Notch1 cleavage and Notch signaling in vitro and in vivo. Taken together, we demonstrated that PSEN1_S169del has distinct effects on APP processing and Notch1 cleavage, suggesting that Notch signaling may not be critical for AD pathogenesis and serine169 could be a critical site as a potential target for the development of novel γ-secretase modulators without affecting Notch1 cleavage to treat AD.