Biochemical Markers in Alzheimer's Disease

Exploring the Link Between Exogenous Thyroid Hormones and Dementia Symptoms: A Real-World Disproportionality Analysis of FDA Adverse Event Reporting System

BACKGROUND

A growing body of evidence indicates a strong association between exogenous thyroid hormone (ETH) and brain health. Establishing the potential relationship between ETH therapy and dementia symptoms is crucial for patients with thyroid disorders.

OBJECTIVE

In this study, we investigate the potential association between ETH therapy and dementia symptoms by exploring the Food and Drug Administration Adverse Event Reporting System (FAERS) database.

METHODS

Disproportionality analysis (DPA) was conducted using postmarketing data from the FAERS repository (Q1 2004 to Q4 2023). Cases of dementia symptoms associated with ETH therapy were identified and analyzed through DPA using reporting odds ratios and information component methods. Dose and time-to-onset analyses were performed to assess the association between ETH therapy and dementia symptoms.

RESULTS

A total of 9889 cases of ETH-associated symptoms were identified in the FAERS database. Dementia accounted for a consistent proportion of adverse drug reactions each year (3.4%-6.3%). The DPA indicated an association between ETH therapy and dementia symptoms, which remained significant even across sex, age, and indications. The median time-to-onset of dementia symptoms was 7.5 days, and the median treatment time was 40.5 days. No significant dose-response relationship was observed.

CONCLUSION AND RELEVANCE

This study provides evidence for a link between ETH therapy and dementia. Clinicians are therefore advised to exercise vigilance, conduct comprehensive monitoring, and consider individualized dosing to mitigate potential reactions to ETH drug administration.

Oxidative stress and neurodegenerative diseases: a bidirectional Mendelian randomization study

INTRODUCTION

Oxidative stress (OS) has been linked to neurodegenerative diseases in numerous epidemiological studies; however, whether it is a pathogenesis or a downstream factor remains controversial.

METHODS

A two-sample bidirectional Mendelian randomization (MR) analysis was implemented to examine evidence of causality of 15 OS injury markers with 3 major neurodegenerative diseases using available genome-wide association studies statistics. As a main approach, inverse-variance weighted (IVW) analysis was performed. The weighted-median (WM) analysis was used to validate the relationship. In order to investigate the existence of horizontal pleiotropy and correct the IVW estimate, the Radial MR approach was applied. To gauge the consistency and robustness of the findings, several sensitivity and pleiotropy analyses were used. For this analysis, p < 0.05 indicates a nominally causal association; according to the Bonferroni correction test, p < 0.0011 indicates a statistically significant causal association.

RESULTS

Via IVW and WM, in directional MR, it was genetically predicted that zinc was nominally causally correlated with the risk of Parkinson's disease but not after Bonferroni correction test; alpha-tocopherol was nominally causally correlated with the risk of Amyotrophic lateral sclerosis (ALS) but not after Bonferroni correction test; furthermore, in reverse MR, it was genetically predicted that Alzheimer's disease was causally correlated with uric acid but not after Bonferroni correction test. These above findings were stable across sensitivity and pleiotropy analyses.

CONCLUSIONS

Based on the current study, there is no authentic genetic causal association between OS biomarkers and neurodegenerative diseases. The complex relationship is required to be confirmed in future experimental research.

Anthranilic Acid-G-Protein Coupled Receptor109A-Cytosolic Phospholipase A2-Myelin-Cognition Cascade: A New Target for the Treatment/Prevention of Cognitive Impairment in Schizophrenia, Dementia, and Aging

Cognitive impairment is a core feature of neurodevelopmental (schizophrenia) and aging-associated (mild cognitive impairment and Alzheimer's dementia) neurodegenerative diseases. Limited efficacy of current pharmacological treatments warrants further search for new targets for nootropic interventions. The breakdown of myelin, a phospholipids axonal sheath that protects the conduction of nerve impulse between neurons, was proposed as a neuropathological abnormality that precedes and promotes the deposition of amyloid-β in neuritic plaques. The present review of the recent literature and our own pre- and clinical data suggest (for the first time) that the anthranilic acid (AA)-induced activation of microglial-expressed G-protein coupled receptor (GPR109A) inhibits cytosolic phospholipase A2 (cPLA2), an enzyme that triggers the degradation of myelin and consequently attenuates cognitive impairment. The present review suggests that the up-regulation of AA formation is a sex-specific compensatory (adaptive) reaction aimed to prevent/treat cognitive impairment. The AA-GPR109A-cPLA2-myelin-cognition cascade suggests new nootropic interventions, e.g., the administration of pegylated kynureninase, an enzyme that catalyzes AA formation from Kynurenine (Kyn), a tryptophane catabolite; pegylated interferon-alpha; central and peripheral Kyn aminotransferase inhibitors that increase availability of Kyn as a substrate for AA formation; and vagus nerve stimulation. The cascade predicts nootropic activity of exogenous GPR109A agonists that were designed and underwent clinical trials (unsuccessful) as anti-dyslipidemia agents. The proposed cascade might contribute to the pathogenesis of cognitive impairment. Data on AA in neurodegenerative disorders are scarce, and the proposed cascade needs further exploration in pre- and clinical studies.

A review of chitosan-based nanocarriers as drug delivery systems for brain diseases: Critical challenges, outlooks and promises

The administration of medicinal drugs orally or systemically limits the treatment of specific central nervous system (CNS) illnesses, such as certain types of brain cancers. These methods can lead to severe adverse reactions and inadequate transport of drugs to the brain, resulting in limited effectiveness. The CNS homeostasis is maintained by various barriers within the brain, such as the endothelial, epithelial, mesothelial, and glial barriers, which strictly control the movement of chemicals, solutes, and immune cells. Brain capillaries consist of endothelial cells (ECs) and perivascular pericytes, with pericytes playing a crucial role in maintaining the blood-brain barrier (BBB), influencing new blood vessel formation, and exhibiting secretory capabilities. This article summarizes the structural components and anatomical characteristics of the BBB. Intranasal administration, a non-invasive method, allows drugs to reach the brain by bypassing the BBB, while direct cerebral administration targets specific brain regions with high concentrations of therapeutic drugs. Technical and mechanical tools now exist to bypass the BBB, enabling the development of more potent and safer medications for neurological disorders. This review also covers clinical trials, formulations, challenges, and patents for a comprehensive perspective.

Causal relationships between rheumatoid arthritis and neurodegenerative diseases: a two-sample univariable and multivariable Mendelian randomization study

Background

Observational research has highlighted a potential relationship between rheumatoid arthritis (RA) and neurodegenerative diseases (NDs). However, the confirmation of a causal connection is impeded by the inherent limitations of such studies, including vulnerability to confounding factors and the possibility of reverse causality. This study employs a two-sample Mendelian randomization (MR) approach to assess the causal impact of RA on three NDs, including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS).

Methods

We aggregated data from genome-wide association studies (GWASs) targeting RA or NDs within populations of European descent. Single nucleotide polymorphisms (SNPs) with robust associations to RA were identified as instrumental variables (IVs). To estimate the association between RA and AD, PD, and ALS, we utilized the inverse variance weighted (IVW) method in our univariable MR (UVMR) analysis. Validation of the IVW results ensued through supplementary analyses using MR-Egger and weighted median methods. The multivariable MR (MVMR) analysis was conducted, adjusting for body mass index (BMI), alcohol drinking, and type 2 diabetes mellitus (T2DM).

Results

The UVMR analysis, based on the IVW method, revealed a significantly positive causal association between RA and late-onset (LO) AD (OR [95% CI] = 1.084 [1.020-1.153]; p = 9.980 × 10-3), while suggesting a possible inverse relationship with PD (OR [95% CI] = 0.727 [0.563-0.938]; p = 0.014). Our study did not detect any causal connections between RA and early-onset (EO) AD, atypical or mixed (AM) AD, and ALS (all p > 0.05). The MVMR analysis results indicated that after adjusting for alcohol drinking, RA remains a risk factor for LOAD (OR [95% CI] = 1.094 [1.024-1.169]; p = 0.008). However, MVMR analysis revealed no causal connections between RA and PD after adjustments for BMI, alcohol drinking, or T2DM (all p > 0.05). Sensitivity analyses showed no evidence of heterogeneity and horizontal pleiotropy.

Conclusions

This research provides genetic evidence indicating that RA potentially causes an increased risk of developing LOAD and PD. Such a revelation underscores the importance for individuals suffering from RA to be vigilant about the potential emergence of LOAD and PD. Ongoing monitoring and prompt detection are essential for successfully managing and intervening in this possible risk.

Caloric restriction leading to attenuation of experimental Alzheimer's disease results from alterations in gut microbiome

BACKGROUND

Caloric restriction (CR) might be effective for alleviating/preventing Alzheimer's disease (AD), but the biological mechanisms remain unclear. In the current study, we explored whether CR caused an alteration of gut microbiome and resulted in the attenuation of cognitive impairment of AD animal model.

METHODS

Thirty-week-old male APP/PS1 transgenic mice were used as AD models (AD mouse). CR was achieved by 30% reduction of daily free feeding (ad libitum, AL) amount. The mice were fed with CR protocol or AL protocol for six consecutive weeks.

RESULTS

We found that with CR treatment, AD mice showed improved ability of learning and spatial memory, and lower levels of Aβ40, Aβ42, IL-1β, TNF-α, and ROS in the brain. By sequencing 16S rDNA, we found that CR treatment resulted in significant diversity in composition and abundance of gut flora. At the phylum level, Deferribacteres (0.04%), Patescibacteria (0.14%), Tenericutes (0.03%), and Verrucomicrobia (0.5%) were significantly decreased in CR-treated AD mice; at the genus level, Dubosiella (10.04%), Faecalibaculum (0.04%), and Coriobacteriaceae UCG-002 (0.01%) were significantly increased in CR-treated AD mice by comparing with AL diet.

CONCLUSIONS

Our results demonstrate that the attenuation of AD following CR treatment in APP/PS1 mice may result from alterations in the gut microbiome. Thus, gut flora could be a new target for AD prevention and therapy.

Biomarkers of Bipolar Disorder in Late Life: An Evidence-Based Systematic Review

PURPOSE OF REVIEW

Review the current evidence on biomarkers for bipolar disorder in the older adults. We conducted a systematic search of PubMed MEDLINE, PsycINFO, and Web of Science databases using the MeSH search terms "Biomarkers", "Bipolar Disorder", "Aged" and and "Aged, 80 and over". Studies were included if they met the following criteria: (1) the mean age of the study population was 50 years old or older, (2) the study included patients with bipolar disorder, and (3) the study examined one type of biomarkers or more including genetic, neuroimaging, and biochemical biomarkers. Reviews, case reports, studies not in English and studies for which no full text was available were excluded. A total of 26 papers were included in the final analysis.

RECENT FINDINGS

Genomic markers of bipolar disorder in older adults highlighted the implication of serotonin metabolism, while the expression of genes involved in angiogenesis was dysregulated. Peripheral blood markers were mainly related with low grade inflammation, axonal damage, endothelial dysfunction, and the dysregulation of the HPA axis. Neuroanatomical markers reflected a dysfunction of the frontal cortex, a loss of neurones in the anterior cingulate cortex and a reduction of the hippocampal volume (in patients older than 50 years old). While not necessarily limited to older adults, some of them may be useful for differential diagnosis (neurofilaments), disease staging (homocysteine, BDNF) and the monitoring of treatment outcomes (matrix metalloproteinases). Our review provides a comprehensive overview of the current evidence on biomarkers for bipolar disorder in the older adults. The identification of biomarkers may aid in the diagnosis, treatment selection, and monitoring of bipolar disorder in older adults, ultimately leading to improved outcomes for this population. Further research is needed to validate and further explore the potential clinical utility of biomarkers in this population.

Identification and Analysis of Axolotl Homologs for Proteins Implicated in Human Neurodegenerative Proteinopathies

Neurodegenerative proteinopathies such as Alzheimer's Disease are characterized by abnormal protein aggregation and neurodegeneration. Neuroresilience or regenerative strategies to prevent neurodegeneration, preserve function, or restore lost neurons may have the potential to combat human proteinopathies; however, the adult human brain possesses a limited capacity to replace lost neurons. In contrast, axolotls (Ambystoma mexicanum) show robust brain regeneration. To determine whether axolotls may help identify potential neuroresilience or regenerative strategies in humans, we first interrogated whether axolotls express putative proteins homologous to human proteins associated with neurodegenerative diseases. We compared the homology between human and axolotl proteins implicated in human proteinopathies and found that axolotls encode proteins highly similar to human microtubule-binding protein tau (tau), amyloid precursor protein (APP), and β-secretase 1 (BACE1), which are critically involved in human proteinopathies like Alzheimer's Disease. We then tested monoclonal Tau and BACE1 antibodies previously used in human and rodent neurodegenerative disease studies using immunohistochemistry and western blotting to validate the homology for these proteins. These studies suggest that axolotls may prove useful in studying the role of these proteins in disease within the context of neuroresilience and repair.

Targeting blood brain barrier-Remote ischemic conditioning alleviates cognitive impairment in female APP/PS1 rats

AIMS

Alzheimer's disease (AD) is a significant global health concern, and it is crucial that we find effective methods to prevent or slow down AD progression. Recent studies have highlighted the essential role of blood vessels in clearing Aβ, a protein that contributes to AD. Scientists are exploring blood biomarkers as a potential tool for future AD diagnosis. One promising method that may help prevent AD is remote ischemic conditioning (RIC). RIC involves using sub-lethal ischemic-reperfusion cycles on limbs. However, a comprehensive understanding of how RIC can prevent AD and its long-term effectiveness is still lacking. Further research is essential to fully comprehend the potential benefits of RIC in preventing AD.

METHODS

Female wild-type (WT) and APP/PS1 transgenic rats, aged 12 months, underwent ovariectomy and were subsequently assigned to WT, APP/PS1, and APP/PS1 + RIC groups. RIC was conducted five times a week for 4 weeks. The rats' depressive and cognitive behaviors were evaluated using force swimming, open-field tests, novel objective recognition, elevated plus maze, and Barnes maze tests. Evaluation of the neurovascular unit (NVU), synapses, vasculature, astrocytes, and microglia was conducted using immunofluorescence staining (IF), Western blot (WB), and transmission electron microscopy (TEM). Additionally, the cerebro-vasculature was examined using micro-CT, and cerebral blood flow (CBF) was measured using Speckle Doppler. Blood-brain barrier (BBB) permeability was determined by measuring the Evans blue leakage. Finally, Aβ levels in the rat frontal cortex were measured using WB, ELISA, or IF staining.

RESULTS

RIC enhanced memory-related protein expression and rescued depressive-like behavior and cognitive decline in APP/PS1 transgenic rats. Additionally, the intervention protected NVU in the rat frontal cortex, as evidenced by (1) increased expression of TJ (tight junction) proteins, pericyte marker PDGFRβ, and glucose transporter 1 (GLUT1), as well as decreased VCAM1; (2) mitigation of ultrastructure impairment in neuron, cerebral vascular, and astrocyte; (3) upregulation of A2 astrocyte phenotype markers and downregulation of A1 phenotype markers, indicating a shift toward a healthier phenotype. Correspondingly, RIC intervention alleviated neuroinflammation, as evidenced by the decreased Iba1 level, a microglia marker. Meanwhile, RIC intervention elevated CBF in frontal cortex of the rats. Notably, RIC intervention effectively suppressed Aβ toxicity, as demonstrated by the enhancement of α-secretase and attenuation of β-secretase (BACE1) and γ- secretase and Aβ1-42 and Aβ1-40 levels as well.

CONCLUSION

Chronic RIC intervention exerts vascular and neuroprotective roles, suggesting that RIC could be a promising therapeutic strategy targeting the BBB and NVU during AD development.

The Protective Effects of High-Intensity Interval Training Combined with Q10 Supplementation on Learning and Memory Impairments in Male Rats with Amyloid-β-Induced Alzheimer's Disease

Background

Oxidative stress plays a major role in the progression of Alzheimer's disease (AD)-related cognitive deficits.

Objective

This study was done to determine the protective effects of coenzyme Q10 (CoQ10) and high-intensity interval training (HIIT) alone and in combination for eight continuous weeks, on oxidative status, cognitive functions, and histological changes in the hippocampus in amyloid-β (Aβ)-induced AD rats.

Methods

Ninety male Wistar rats were randomly assigned to the sham, control, Q10 (50 mg/kg of CoQ10; P.O.), HIIT (high intensity: 4 min running at 85-90% VO2max, low intensity: 3 min running at 50-60% VO2max), Q10 + HIIT, AD, AD+Q10, AD+HIIT, and AD+Q10 + HIIT groups.

Results

The results showed that Aβ injection reduced cognitive functions in the Morris water maze (MWM) test and recognition memory in the novel object recognition test (NORT), which was accompanied by a decrease in total thiol groups, catalase, and glutathione peroxidase activities, an increase in malondialdehyde levels, and neuronal loss in the hippocampus. Interestingly, pretreatment with CoQ10, HIIT, or both, could markedly improve the oxidative status and cognitive decline in the MWM and NOR tests, and hinder neuronal loss in the hippocampus of Aβ-induced AD rats.

Conclusion

Therefore, a combination of CoQ10 and HIIT can improve Aβ-related cognitive deficits, probably through an amelioration in hippocampal oxidative status and prevention of neuronal loss.

Detection of APP gene recombinant in human blood plasma

The pathogenesis of Alzheimer's disease (AD) is believed to involve the accumulation of amyloid-β in the brain, which is produced by the sequential cleavage of amyloid precursor protein (APP) by β-secretase and γ-secretase. Recently, analysis of genomic DNA and mRNA from postmortem brain neurons has revealed intra-exonic recombinants of APP (gencDNA), which have been implicated in the accumulation of amyloid-β. In this study, we computationally analyzed publicly available sequence data (SRA) using probe sequences we constructed to screen APP gencDNAs. APP gencDNAs were detected in SRAs constructed from both genomic DNA and RNA obtained from the postmortem brain and in the SRA constructed from plasma cell-free mRNA (cf-mRNA). The SRA constructed from plasma cf-mRNA showed a significant difference in the number of APP gencDNA reads between SAD and NCI: the p-value from the Mann-Whitney U test was 5.14 × 10-6. The transcripts were also found in circulating nucleic acids (CNA) from our plasma samples with NGS analysis. These data indicate that transcripts of APP gencDNA can be detected in blood plasma and suggest the possibility of using them as blood biomarkers for Alzheimer's disease.

Identification of genes related to glucose metabolism and analysis of the immune characteristics in Alzheimer's disease

OBJECTIVE

Glucose metabolism plays a crucial role in the progression of Alzheimer's disease (AD). The purpose of this study is to identify genes related to glucose metabolism in AD by bioinformatics, construct an early AD prediction model from the perspective of glucose metabolism, and analyze the characteristics of immune cell infiltration.

METHODS

AD-related modules and genes were screened by weighted gene co-expression network analysis (WGCNA). The GO and KEEG enrichment analysis were used to explore the potential biological functions of glucose metabolism related genes (GMRGs) in AD. The Least Absolute Shrinkage Selection Operator (LASSO) method was used to construct an early AD prediction model based on GMRGs. Then, the receiver operating characteristic curve (ROC) and nomogram were introduced to evaluate the effectiveness of this model. Finally, CIBERSORT and single-cell analysis were applied for illustrating the immune characteristics in AD patients.

RESULTS

A total of 462 differential expressed genes (DEGs) were obtained between Non-Alzheimer's disease (ND,) and AD groups. The genes in the blue module had the highest correlation with AD by WGCNA analysis. We found 18 intersected genes among DEGs, blue model genes and GMRGs according to the Venn diagram. The GO and KEEG enrichment analysis showed that these 18 genes were mainly involved in the production of metabolites and energy, glycolysis, amino acid biosynthesis and so on. The early AD prediction model including ENO2, TPI1, AEBP1, HERC1, PCSK1, PREPL, SLC25A4, UQCRC2, CHST6, DDIT4, ACSS1 and SUCLA2 was constructed by LASSO analysis. The area under the curve (AUC) of this model in brain tissues was 0.942. Then, we draw the nomogram of this model and the C-index was 0.942. The model was further validated in blood samples and the AUC was 0.644. Immune cell infiltration analysis showed that the proportion of plasma cells, T cells follicular helper and activated NK cells in AD group were significantly lower than ND group, while the proportion of M1 macrophages, neutrophils, T cells CD4 naive and γ-δ T cells was significantly increased when compared with the ND group. Additionally, the specific GMRGs such as ENO2, DDIT4, and SUCLA2 are significantly correlated with certain immune cells such as plasma cells, follicular helper T cells, and M1 macrophages. Single-cell analysis results suggested that the increased macrophages in AD was associated with the up-regulation of AEBP1, DDIT4 and ACSS1.

CONCLUSIONS

The diagnosis model based on the twelve GMRGs has strong predictive ability and can be used as early diagnosis biomarkers for AD. In addition, these GMRGs closely associate with AD development by influencing the glucose metabolism of immune cells.

Efficacy evaluation and metabolomics analysis of Huanglian Jiedu decoction in combination with donepezil for Alzheimer's disease treatment

Alzheimer's disease (AD) is a progressive disease with continuous brain changes and has caused a severe burden on families and society. Huanglian Jiedu Decoction (HLJD) is a classic traditional Chinese medicine formula that can improve AD animals' cognitive impairment. This study recruited 50 AD patients who were divided into two groups, one receiving donepezil (DON) treatment and the other receiving DON + HLJD treatment for 3 months. The curative effect, inflammatory and oxidative stress levels were analyzed. The PES-D/11, MMSE, and ADL scales were used to evaluate traditional Chinese medicine syndrome elements, cognitive function, mental state, and life ability. There were no significant differences between the two groups in baseline characteristics and vital sign indicators. After drug treatment, the results showed that AD patients with HLJD combined with DON treatment didn't increase the adverse effects and had good compliance. HLJD combined with DON could improve the disease syndrome, making the differences in PES-D/11, MMSE, and ADL scores before and after the intervention larger. Furthermore, both DON and DON+HLJD treatment inhibited the levels of IL-6, IL-1β, TNF-α, and MDA, raised SOD level, and HLJD enhances the inhibitory effect of DON on inflammation and oxidative stress. IL-6, IL-1β, TNF-α, and MDA levels were significantly correlated with curative effect. Moreover, this study found 107 (206) up-regulated metabolites and 1430 (145) down-regulated metabolites in urine (serum) and conducted differential metabolite screening and correlation analysis suggesting that HLJD may interfere with oxidative stress and inflammation in AD by regulating lipid metabolism and glutamic acid metabolism. Arachidonic acid, diaminopimelic acid, and 1-Aminocyclopropanecarboxylic acid may play an important role in HLJD to improve AD.

The Impact of Neurotransmitters on the Neurobiology of Neurodegenerative Diseases

Neurodegenerative diseases affect millions of people worldwide. Neurodegenerative diseases result from progressive damage to nerve cells in the brain or peripheral nervous system connections that are essential for cognition, coordination, strength, sensation, and mobility. Dysfunction of these brain and nerve functions is associated with Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, and motor neuron disease. In addition to these, 50% of people living with HIV develop a spectrum of cognitive, motor, and/or mood problems collectively referred to as HIV-Associated Neurocognitive Disorders (HAND) despite the widespread use of a combination of antiretroviral therapies. Neuroinflammation and neurotransmitter systems have a pathological correlation and play a critical role in developing neurodegenerative diseases. Each of these diseases has a unique pattern of dysregulation of the neurotransmitter system, which has been attributed to different forms of cell-specific neuronal loss. In this review, we will focus on a discussion of the regulation of dopaminergic and cholinergic systems, which are more commonly disturbed in neurodegenerative disorders. Additionally, we will provide evidence for the hypothesis that disturbances in neurotransmission contribute to the neuronal loss observed in neurodegenerative disorders. Further, we will highlight the critical role of dopamine as a mediator of neuronal injury and loss in the context of NeuroHIV. This review will highlight the need to further investigate neurotransmission systems for their role in the etiology of neurodegenerative disorders.

Hippocampal injections of soluble amyloid-beta oligomers alter electroencephalographic activity during wake and slow-wave sleep in rats

BACKGROUND

Soluble amyloid-beta oligomers (Aβo) begin to accumulate in the human brain one to two decades before a clinical diagnosis of Alzheimer's disease (AD). The literature supports that soluble Aβo are implicated in synapse and neuronal losses in the brain regions such as the hippocampus. This region importantly contributes to explicit memory, the first type of memory affected in AD. During AD preclinical and prodromal stages, people are also experiencing wake/sleep alterations such as insomnia (e.g., difficulty initiating sleep, decreased sleep duration), excessive daytime sleepiness, and sleep schedule modifications. In addition, changes in electroencephalographic (EEG) activity during wake and sleep have been reported in AD patients and animal models. However, the specific contribution of Aβo to wake/sleep alterations is poorly understood and was investigated in the present study.

METHODS

Chronic hippocampal injections of soluble Aβo were conducted in male rats and combined with EEG recording to determine the progressive impact of Aβ pathology specifically on wake/sleep architecture and EEG activity. Bilateral injections were conducted for 6 consecutive days, and EEG acquisition was done before, during, and after Aβo injections. Immunohistochemistry was used to assess neuron numbers in the hippocampal dentate gyrus (DG).

RESULTS

Aβo injections did not affect the time spent in wakefulness, slow wave sleep (SWS), and paradoxical sleep but altered EEG activity during wake and SWS. More precisely, Aβo increased slow-wave activity (SWA; 0.5-5 Hz) and low-beta activity (16-20 Hz) during wake and decreased theta (5-9 Hz) and alpha (9-12 Hz) activities during SWS. Moreover, the theta activity/SWA ratio during wake and SWS was decreased by Aβo. These effects were significant only after 6 days of Aβo injections and were found with alterations in neuron counts in the DG.

CONCLUSIONS

We found multiple modifications of the wake and SWS EEG following Aβo delivery to the hippocampus. These findings expose a specific EEG signature of Aβ pathology and can serve the development of non-invasive and cost-effective markers for the early diagnosis of AD or other amyloid-related diseases.

A meta-analysis of neurogenic exosomes in the diagnosis of Alzheimer's disease

Background

Alzheimer's disease (AD) is an irreversible and difficult-to-treat neurodegenerative disease. It is necessary to search for reliable biomarkers for the early diagnosis of AD in a timely and effective manner in high-risk or preclinical AD populations. Studies have shown that neurogenic exosomes in the blood can be effectively used as biomarkers for AD.

Objective

In this meta-analysis, we aimed to find reliable biomarkers (Aβ42, T-tau, and P-tau181 in peripheral blood neurogenic exosomes) for the early diagnosis of AD to provide theoretical support for the early diagnosis of high-risk or preclinical AD populations.

Methods

By searching the literature database, relevant studies on AD diagnostic markers were collected. The study period was from April 1, 2012, to April 1, 2022. The average concentrations of Aβ42, T-tau, and P-tau181 in the exosomes of the AD group and healthy control group were compared using RevMan 5.3 software.

Results

A total of 13 studies were screened, including 842 subjects. Meta-analysis showed that the combined SMD value of neurogenic exosome Aβ42 was 1.70 (95% CI = [1.20,2.20], Z = 6.69, P < 0.05). The combined SMD value of T-tau was 1.02 (95% CI = [0.27,1.77], Z = 2.67, P < 0.05). The combined SMD value of P-tau181 was 1.75 (95% CI = [1.16, 2.35], Z = 5.75, P < 0.05). The levels of neurogenic exosomes Aβ42, T-tau, and P-tau181 in AD patients were significantly higher than those in healthy controls.

Conclusion

Aβ42, T-tau, and P-tau181 in blood neurogenic exosomes can be effectively used as biomarkers for AD and can be applied in the diagnosis, screening, prognosis prediction and disease monitoring of AD.

Serum sirtuin1: a potential blood biomarker for early diagnosis of Alzheimer's disease

BACKGROUND

Sirtuin 1, a nicotinamide adenine dinucleotide-dependent deacetylase that is highly expressed in the hippocampus and anterior cortex tissues related to Alzheimer's Disease pathology, can cross the blood-brain barrier and is a promising biomarker.

METHODS

A 1:1:1 case-control study was conducted and serum fasting blood glucose, triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, SIRT1, IL-6, Aβ1-42, T-tau and P-tau-181 levels were evaluated in blood samples of 26 patients form the Alzheimer's Disease group, 26 patients form the mild cognitive impairment group, and 26 individuals form the normal control group. Receiver operator characteristic curves were used to evaluate the diagnostic significance.

RESULTS

Serum SIRT1 level was significantly down-regulated in the mild cognitive impairment patients and Alzheimer's Disease patients compared with that in the normal control group (P<0.05). ROC curve analysis demonstrated that SIRT1 was a promising biomarker to distinguish Alzheimer's Disease patients from the mild cognitive impairment patients and the normal control group. In addition, SIRT1 was estimated to perform well in the diagnosis of Alzheimer's Disease ([AUC] = 0.742).

CONCLUSIONS

In summary, the present study suggested that serum SIRT1 might be an early promising diagnostic biomarker for Alzheimer's Disease.

Assessing causal relationship between circulating cytokines and age-related neurodegenerative diseases: a bidirectional two-sample Mendelian randomization analysis

Numerous studies have reported that circulating cytokines (CCs) are linked to age-related neurodegenerative diseases (ANDDs); however, there is a lack of systematic investigation for the causal association. A two-sample bidirectional Mendelian Randomisation (MR) method was utilized to evaluate the causal effect. We applied genetic variants correlated with concentrations of CCs from a genome-wide association study meta-analysis (n = 8293) as instrumental variables. Summary data of three major ANDDs [Alzheimer's disease (AD), Parkinson's disease (PD), and Amyotrophic lateral sclerosis (ALS)] were identified from the IEU OpenGWAS platform (n = 627, 266). Inverse-variance weighted method is the main approach to analyse causal effect, and MR results are verified by several sensitivity and pleiotropy analyses. In directional MR, it suggested that several CCs were nominally correlated with the risk of ANDDs, with a causal odds ratio (OR) of Interleukin (IL)-5 of 0.909 for AD; OR of IL-2 of 1.169 for PD; and OR of Beta nerve growth factor of 1.142 for ALS). In reverse MR, there were some suggestively causal effects of ANDDs on CCs (AD on increased Basic fibroblast growth factor and IL-12 and decreased Stem cell growth factor beta; PD on decreased Monokine induced by interferon-gamma; ALS on decreased Basic fibroblast growth factor and IL-17). The findings were stable across sensitivity and pleiotropy analyses. However, after Bonferroni correction, there is no statistically significant association between CCs and ANDDs. Through the genetic epidemiological approach, our study assessed the role and presented possible causal associations between CCs and ANDDs. Further studies are warranted to verify the causal associations.

A New Optical Interferometric Biosensing System Enhanced with Nanoparticles for Alzheimer's Disease in Serum

In this scientific work, we demonstrate, for the first time, a new biosensing system and procedure to measure specifically the total Tau (T-Tau) protein in serum, one of the most relevant biomarkers of Alzheimer's disease (AD). AD is a progressive brain disorder that produces neuronal and cognitive dysfunction and affects a high percentage of people worldwide. For this reason, diagnosing AD at the earliest possible stage involves improving diagnostic systems. We report on the use of interferometric bio-transducers integrated with 65 microwells forming diagnostic KITs read-out by using the Interferometric Optical Detection Method (IODM). Moreover, biofunctionalized silicon dioxide (SiO₂) nanoparticles (NPs) acting as interferometric enhancers of the bio-transducers signal allow for the improvement of both the optical read-out signal and its ability to work with less-invasive biological samples such as serum instead of cerebrospinal fluid (CSF). As a result, in this paper, we describe for the first time a relevant diagnostic alternative to detect Tau protein at demanding concentrations of 10 pg/mL or even better, opening the opportunity to be used for detecting other relevant AD-related biomarkers in serum, such as β-amyloid and phosphorylated Tau (P-Tau), neurofilaments, among others that can be considered relevant for AD.

The electrophysiological and neuropathological profiles of cerebellum in APPswe /PS1ΔE9 mice: A hypothesis on the role of cerebellum in Alzheimer's disease

We propose the hypothesis that the cerebellar electrophysiology and sleep-wake cycles may be altered at the early stage of Alzheimer's disease (AD), proceeding the amyloid-β neuropathological hallmarks. The electrophysiologic characteristics of cerebellum thereby might be served as a biomarker in the prepathological detection of AD. Sleep disturbances are common in preclinical AD patients, and the cerebellum has been implicated in sleep-wake regulation by several pioneer studies. Additionally, recent studies suggest that the structure and function of the cerebellum may be altered at the early stages of AD, indicating that the cerebellum may be involved in the disease's progression. We used APPswe /PS1ΔE9 mice as a model of AD, monitored and analyzed electroencephalogram data, and assessed neuropathological profiles in the cerebellum of AD mice. Our hypothesis may establish a linkage between the cerebellum and AD, thereby potentially providing new perspectives on the pathogenesis of the disease.

Competitive fluorescent immunoassay for the ultrasensitive determination of amyloid beta peptide1-42 based on Ag@SiO2@N, S-GQD nanocomposites

A competitive fluorescent immunoassay is described for the ultrasensitive determination of amyloid beta peptide1-42 (Aβ1-42), a biomarker for early diagnosis of Alzheimer's disease. N, S-doped graphene quantum dots (N, S-GQDs) were freely assembled on the surface of Ag@SiO₂ nanoparticles to obtain a composite (Ag@SiO₂@N, S-GQD nanocomposite), which was successfully prepared and characterized. By theoretical study, the optical properties of nanocomposites are improved compared with GQDs, due to the advantages of combining N, S co-doping and metal-enhanced fluorescence (MEF) effect of Ag NPs. In addition, Aβ1-42 was modified by Ag@SiO₂@N, S-GQDs to prepare a probe with high photoluminescence properties (Ag@SiO₂@N, S-GQDs-Aβ1-42). In the presence of Aβ1-42, a competitive reaction towards anti-Aβ1-42 fixed on the ELISA plate was proceeded between Aβ1-42 and Ag@SiO₂@N, S-GQDs-Aβ1-42 by specific capture of antigen-antibody. The emission peak of Ag@SiO₂@N, S-GQDs-Aβ1-42 (400 nm emission) was used for the quantitative determination of Aβ1-42. Under the optimal conditions, the fluorescent immunoassay exhibited a linear range of 0.32 pg·mL^-1-5 ng·mL^-1 with a detection limit of 0.098 pg·mL^-1. The results show that the immunoassay has good analytical ability and can provide a new method for the clinical determination of Aβ1-42.

Focus on Alzheimer's Disease: The Role of Fibroblast Growth Factor 21 and Autophagy

Alzheimer's disease (AD) is a disorder of the central nervous system that is typically marked by progressive cognitive impairment and memory loss. Amyloid β plaque deposition and neurofibrillary tangles with hyperphosphorylated tau are the two hallmark pathologies of AD. In mammalian cells, autophagy clears aberrant protein aggregates, thus maintaining proteostasis as well as neuronal health. Autophagy affects production and metabolism of amyloid β and accumulation of phosphorylated tau proteins, whose malfunction can lead to the progression of AD. On the other hand, defective autophagy has been found to induce the production of the neuroprotective factor fibroblast growth factor 21 (FGF21), although the underlying mechanism is unclear. In this review, we highlight the significance of aberrant autophagy in the pathogenesis of AD, discuss the possible mechanisms by which defective autophagy induces FGF21 production, and analyze the potential of FGF21 in the treatment of AD. The findings provide some insights into the potential role of FGF21 and autophagy in the pathogenesis of AD.

p75NTR enhances cognitive dysfunction in a mouse Alzheimer's disease model by inhibiting microRNA-210-3p-mediated PCYT2 through activation of NF-κB

Alzheimer's disease (AD) is a main cause of dementia and exhibits abnormality in cognitive behaviors. Here, we probed into the role of p75 neurotrophin receptor (p75NTR) in cognitive dysfunction in AD. Primarily, C57BL/6 mouse and neuroblastoma cells were treated by amyloid-beta1-42 (Aβ_1-42), respectively, to establish the in vivo and in vitro models of AD. The downstream genes of p75NTR were predicted by RNA-sequencing and bioinformatics analysis. Then the interaction among p75NTR, nuclear factor kappa B (NF-κB), microRNA-210-3p (miR-210-3p) and phosphoethanolamine cytidylyltransferase 2 (PYCT2) was verified, followed by analysis of their effects on cognitive behaviors and biological characteristics of hippocampal neurons of mouse with AD-like symptoms. p75NTR knockout alleviated cognitive dysfunction in mice with AD-like symptoms and reduced Aβ_1-42-induced hippocampal neuron damage and apoptosis. p75NTR up-regulated miR-210-3p expression by activating NF-κB, thereby limiting PCYT2 expression. PCYT2 silencing in p75NTR^-/- mice promoted neuronal apoptosis and aggravated cognitive dysfunction in AD mouse models. In summary, p75NTR is capable of accelerating cognitive dysfunction in AD by mediating the NF-κB/miR-210-3p/PCYT2 axis.

Alzheimer's Disease-Biochemical and Psychological Background for Diagnosis and Treatment

There is a paucity of empirical research on the use of non-pharmacological interventions to both treat and curb the spread of Alzheimer's disease (AD) across the globe. This paper examines the biochemical and clinical outlook and the social implications of the condition in relation to psychological aspects that may indicate a direction for further interventions. There is a scarcity of research on the effectiveness of using various psychological aspects of AD, a disease characterized by a process of transition from health and independence to a dependent state with a progressive loss of memory and functional skills. The paper investigates the biochemical and psychological aspects of AD and their significance for improving quality of life for patients with this disease. Psychological interventions based on, among other factors, biochemical studies, are conducted to improve the emotional wellbeing of AD patients and may assist in slowing down the progression of the disease. To date, however, no effective methods of AD treatment have been established.

Alzheimer's Disease Neuropathologic Change and Vitamin Supplement Use Decades Earlier: The 90+ Study

BACKGROUND

Alzheimer's disease (AD) is the most common cause of dementia. AD neuropathologic change (ADNC) likely begins decades before clinical manifestations. One mechanism implicated in AD is oxidative stress. We explored the potential association of ADNC with antioxidant vitamin supplements taken about 30 years before death.

METHODS

The 264 brain-autopsied participants were part of The 90+ Study, a longitudinal study of aging among people aged 90+ years, and originally members of the Leisure World Cohort Study, a population-based health study established in the 1980s. Intake of supplemental vitamins A, C, and E was collected by the Leisure World Cohort Study about 30 years before ADNC assessment. Odds ratios of ADNC (intermediate/high vs. none/low) for vitamin intake were estimated using logistic regression.

RESULTS

The adjusted odds ratio (95% CI) of ADNC was 0.52 (0.29-0.92) for vitamin E supplements and 0.51 (0.27-0.93) for vitamin C supplements. Supplemental vitamin E intake was the first variable, after education, to enter the stepwise model. Intake of vitamin A or C did not improve the model fit.

CONCLUSIONS

The observed association of ADNC and supplemental vitamin E intake decades earlier suggests a beneficial effect and supports further investigation into a nutritional approach to preventing AD with vitamin supplementation.

iTRAQ-Based Proteomic Analysis of APP Transgenic Mouse Urine Exosomes

Alzheimer's disease (AD) is a common dementia disease in the elderly. To get a better understanding of the pathophysiology, we performed a proteomic analysis of the urine exosomes (U-exo) in AD model mice (J20). The polymer precipitation method was used to isolate U-exo from the urine of 3-month-old J20 and wild-type (WT) mice. Neuron-derived exosome (N-exo) was isolated from U-exo by immunoprecipitation. iTRAQ-based MALDI TOF MS/MS was used for proteomic analysis. The results showed that compared to WT, the levels of 61 and 92 proteins were increased in the J20 U-exo and N-exo, respectively. Gene ontology enrichment analysis demonstrated that the sphingolipid catabolic process, ceramide catabolic process, membrane lipid catabolic process, Aβ clearance, and Aβ metabolic process were highly enriched in U-exo and N-exo. Among these, Asah1 was shown to be the key protein in lipid metabolism, and clusterin, ApoE, neprilysin, and ACE were related to Aβ metabolism and clearance. Furthermore, protein-protein interaction analysis identified four protein complexes where clusterin and ApoE participated as partner proteins. Thus, J20 U-exo and N-exo contain proteins related to lipid- and Aβ-metabolism in the early stages of AD, providing a new insight into the underlying pathological mechanism of early AD.

Tanshinone IIA loaded chitosan nanoparticles decrease toxicity of β-amyloid peptide in a Caenorhabditis elegans model of Alzheimer's disease

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases that characterized by the accumulation of β-amyloid peptide (Aβ). Overexpressions of Aβ could induce oxidative stress that might be a key insult to initiate the cascades of Aβ accumulation. As a result, anti-oxidative stress and attenuating Aβ accumulation might be one promising intervention for AD treatment. Tanshinone IIA (Tan IIA), a major component of lipophilic tanshinones in Danshen, is proven to be effective in several diseases, including AD. Due to the poor solubility in water, the clinical application of Tan IIA was limited. Therefore, a great number of nanoparticles were designed to overcome this issue. In the current study, we choose chitson as delivery carrier to load Tanshinone IIA (CS@Tan IIA) and explore the protective effects of CS@Tan IIA on the CL2006 strain, a transgenic C. elegans of AD model organism. Compared with Tan IIA monomer, CS@Tan IIA could significantly prolong the lifespan and attenuate the AD-like symptoms, including reducing paralysis and the Aβ deposition by inhibiting the oxidative stress. The mechanism study showed that the protection of CS@Tan IIA was attenuated by knockdown of daf-16 gene, but not skn-1. The results indicated that DAF-16/SOD-3 pathway was required in the protective effects of CS@Tan IIA. Besides DAF-16/SOD-3 pathway, the Tan IIA-loaded CS nanoparticles might protect the C. elegans against the AD insults via promoting autophagy. All the results consistently suggested that coating by chitosan could improve the solubility of Tan IIA and effectively enhance the protective effects of Tan IIA on AD, which might provide a potential drug loading approach for the hydrophobic drugs as Tan IIA.

Perspectives of ozone induced neuropathology and memory decline in Alzheimer's disease: A systematic review of preclinical evidences

This systematic review aims to discover the plausible mechanism of Ozone in A.D., to boost translational research. The main focus of our review lies in understanding the effects of ozone pollution on the human brain and causing degenerative disease. Owing to the number of works carried out as preclinical evidence in association with oxidative stress and Alzheimer's disease and the lack of systematic review or meta-analysis prompted us to initiate a study on Alzheimer's risk due to ground-level ozone. We found relevant studies from PubMed, ScienceDirect, Proquest, DOAJ, and Scopus, narrowing to animal studies and the English language without any time limit. The searches will be re-run before the final analysis. This work was registered in Prospero with Reg ID CRD42022319360, followed the PRISMA-P framework, and followed the PICO approach involving Population, Intervention/Exposure, Comparison, and Outcomes data. Bibliographic details of 16 included studies were studied for Exposure dose of ozone, duration, exposure, and frequency with control and exposure groups. Primary and secondary outcomes were assessed based on pathology significance, and results were significant in inducing Alzheimer-like pathology by ozone. In conclusion, ozone altered oxidative stress, metabolic pathway, and amyloid plaque accumulation besides endothelial stress response involving mitochondria as the critical factor in ATP degeneration, caspase pathway, and neuronal damage. Thus, ozone is a criteria pollutant to be focused on in mitigating Alzheimer's Disease pathology.

Neuropharmaceutical Properties of Naringin Against Alzheimer's and Parkinson's Diseases: Naringin Protection Against AD and PD

Neurological complications are considered the leading cause of disability and the second cause of death worldwide. Although the most common neurological disorders affecting a large population are Alzheimer's (AD) and Parkinson's diseases (PD), no definitive treatment has been propounded in the clinic. As in recent years, special attention has been paid to medicinal herbal products as one of the ways to meet the challenges of treating diseases. This review study aimed to introduce the naringin neuroprotective effects as an abundant flavonoid in grapes and citrus fruits on the most common neurological disorders, including AD and PD. For this purpose, the specified keywords were searched in PubMed, Web of Science, Scopus, Embase, and Google Scholar, and the results were entered into the study after a concise overview. The findings show naringin can confront neurological disorders through several mechanisms such as modulating stress response pathways, preventing apoptosis, oxidative stress, and neuroinflammation, excessive chelating amounts of metal ions, thereby improving cognitive impairment and memory loss induced by neurological disorders. However, further studies, particularly on human, are critical for the final confirmation of obtained findings. [GMJ.2022;11:e2337].

Effects of Electroacupuncture on the Correlation between Serum and Central Immunity in AD Model Animals

Objective

The goal was to investigate the connection between neuroinflammation in the brain and serum inflammatory markers as Alzheimer's disease progressed. We also sought to determine whether electroacupuncture had an effect on inflammatory markers found in blood and other brain regions.

Methods

As an animal model for AD, we used senescence-accelerated mouse prone 8 (SAMP8) mice. To examine the effects and probable mechanism of electroacupuncture, we used HE staining, immunofluorescence staining, western blotting, and enzyme-linked immunosorbent assay.

Results

Electroacupuncture therapy protected neurons, significantly downregulated the Iba-1 level in the hippocampus (p value was 0.003), frontal lobe cortex (p value was 0.042), and temporal lobe cortex (p value was 0.013) of the AD animal model, all of which had significantly lower levels of IL-6 (p value was 0.001), IL-1β (p value was 0.001), and TNF-α (p value was 0.001) in their serum.

Conclusion

The amounts of IL-6, IL-1β, and TNF-α detected in the serum were strongly linked to the levels discovered in the hippocampus and the frontal lobes of the brain, respectively. A better understanding of the electroacupuncture process as well as the course of Alzheimer's disease and the therapeutic benefits of electroacupuncture may be gained by using biomarkers such as serum inflammatory marker biomarkers.

New Therapeutic Approaches to and Mechanisms of Ginsenoside Rg1 against Neurological Diseases

Neurological diseases, including Parkinson’s disease (PD), Alzheimer’s disease (AD), Huntington’s disease (HD), stroke, cerebral infarction, ischemia-reperfusion injury, depression and, stress, have high incidence and morbidity and often lead to disability. However, there is no particularly effective medication against them. Therefore, finding drugs with a suitable efficacy, low toxicity and manageable effects to improve the quality of life of patients is an urgent problem. Ginsenoside Rg1 (Rg1) is the main active component of ginseng and has a variety of pharmacological effects. In this review, we focused on the therapeutic potential of Rg1 for improving neurological diseases. We introduce the mechanisms of Ginsenoside Rg1 in neurological diseases, including apoptosis, neuroinflammation, the microRNA (miRNA) family, the mitogen-activated protein kinase (MAPK) family, oxidative stress, nuclear factor-κB (NF-κB), and learning and memory of Rg1 in neurological diseases. In addition, Rg1 can also improve neurological diseases through the interaction of different signal pathways. The purpose of this review is to explore more in-depth ideas for the clinical treatment of neurological diseases (including PD, AD, HD, stroke, cerebral infarction, ischemia–reperfusion injury, depression, and stress). Therefore, Rg1 is expected to become a new therapeutic method for the clinical treatment of neurological diseases.

Dysregulated miRNAs in Progression and Pathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive degeneration of neurons due to the accumulation of amyloid-β peptide (Aβ) and hyper-phosphorylation of tau protein in the neuronal milieu leading to increased oxidative stress and apoptosis. Numerous factors contribute towards the progression of AD, including miRNA, which are 22-24 nucleotides long sequence which acts as critical regulators of cellular processes by binding to 3' UTR of mRNA, regulating its expression post-transcriptionally. This review aims to determine the miRNA with the most significant dysregulation in the brain and cerebrospinal fluid (CSF) of human patients. A systemized inclusion/exclusion criterion has been utilized based on selected keywords followed by screening of those articles to conclude a list of 8 highly dysregulated miRNAs based on the fold change of AD vs control patients, which could be used in clinical testing as these miRNAs play central role in the pathophysiology of AD. Furthermore, a network study of highly dysregulated miRNA estimated the association of these miRNA in the mediation of Aβ generation and aggregation, inhibition of autophagy, reduction of Aβ clearance, microglial and astrocytic activation, neuro-inflammation, tau hyper-phosphorylation, and synaptic loss.

Relationship between thyroid hormones and central nervous system metabolism in physiological and pathological conditions

Thyroid hormones (THs) play an important role in the regulation of energy metabolism. They also take part in processes associated with the central nervous system (CNS), including survival and differentiation of neurons and energy expenditure. It has been reported that a correlation exists between the functioning of the thyroid gland and the symptoms of CNS such as cognitive impairment, depression, and dementia. Literature data also indicate the influence of THs on the pathogenesis of CNS diseases, such as Alzheimer's disease, epilepsy, depression, and Parkinson's disease. This review describes the relationship between THs and metabolism in the CNS, the effect of THs on the pathological conditions of the CNS, and novel options for treating these conditions with TH derivatives.

The Role of Exosomes as Mediators of Neuroinflammation in the Pathogenesis and Treatment of Alzheimer’s Disease

Alzheimer’s disease (AD) is a common neurodegenerative disease characterized by progressive dementia. Accumulation of β–amyloid peptide 1–42 and phosphorylation of tau protein in the brain are the two main pathological features of AD. However, comprehensive studies have shown that neuroinflammation also plays a crucial role in the pathogenesis of AD. Neuroinflammation is associated with neuronal death and abnormal protein aggregation and promotes the pathological process of β-amyloid peptide 1–42 and tau protein. The inflammatory components associated with AD include glial cells, complement system, cytokines and chemokines. In recent years, some researchers have focused on exosomes, a type of membrane nano vesicles. Exosomes can transport proteins, lipids, microRNAs and other signaling molecules to participate in a variety of signaling pathways for signal transmission or immune response, affecting the activity of target cells and participating in important pathophysiological processes. Therefore, exosomes play an essential role in intercellular communication and may mediate neuroinflammation to promote the development of AD. This paper reviews the occurrence and development of neuroinflammation and exosomes in AD, providing a deeper understanding of the pathogenesis of AD. Furthermore, the role of exosomes in the pathogenesis and treatment of AD is further described, demonstrating their potential as therapeutic targets for neuroinflammation and AD in the future.

Association between obstructive sleep apnea and Alzheimer's disease-related blood and cerebrospinal fluid biomarkers: A meta-analysis

INTRODUCTION

Recent studies indicate that Alzheimer's disease- (AD) related biomarkers, including amyloid β (Aβ40 and Aβ42) and tau proteins (P-tau and T-tau), in blood and cerebrospinal fluid (CSF) are associated with obstructive sleep apnea (OSA). However, the results have been inconsistent. Therefore, the primary purpose of this meta-analysis was to determine the relationship between blood and CSF AD-related biomarkers and OSA.

METHODS

We searched the Embase, PubMed, Scopus, and Cochrane Library databases for relevant articles till February 2022.

RESULTS

Eight articles were finally included after the literature screening, including 446 patients with OSA and 286 controls. Pooled analysis showed that CSF Aβ42 (SMD = -0.220, P = 0.136), T-tau (SMD = 0.012, P = 0.89), and P-tau (SMD = 0.099, P = 0.274) levels were not different between patients with OSA and controls. In patients with moderate to severe OSA, CSF Aβ42 (SMD = -0.482, P = 0.031) were significantly lower than in controls. Blood T-tau (SMD = 0.560, P = 0.026), P-tau (SMD = 0.621, P < 0.001), and Aβ40 (SMD = 0.656, P < 0.001) levels were significantly higher in patients with OSA than in controls. Blood Aβ42 (SMD = 0.241, P = 0.232) were not different between patients with OSA and controls.

CONCLUSION

OSA is associated with changes in AD-related markers. Higher OSA severity may be associated with the development of AD. AD-related biomarkers, especially in the blood, are clinically efficient, less invasively assessed and monitored, and may be useful for detecting OSA and related cognitive impairments. Further studies are needed to confirm these results.

The Influence of 24-h Ambulatory Blood Pressure on Cognitive Function and Neuropathological Biomarker in Patients With Alzheimer's Disease

Purpose

This study aimed to investigate the influence of 24-h ambulatory blood pressure (BP) on cognitive function and neuropathological biomarkers in patients with Alzheimer's disease (AD) at the stages of mild cognitive impairment (MCI) and dementia.

Methods

The patients with AD were divided into the MCI (AD-MCI) group and the dementia (AD-D) group. Notably, 24-h BP variables, including BP level, coefficient of variation (CV) of BP, and pulse pressure, were collected and compared between the two groups. The correlations between 24-h BP variables and the scores of cognitive domains were analyzed. The independent influencing factors of cognitive domains of patients with AD were investigated. The levels of neuropathological biomarkers of AD, including β amyloid (Aβ)1−42, phosphorylated tau (P-tau), and total tau (T-tau), in cerebrospinal fluid (CSF) were measured and compared between the two groups, and the correlations between 24-h BP variables and the levels of neuropathological biomarkers of AD were analyzed.

Results

Daytime CV of systolic BP (SBP) was significantly increased in the AD-D group compared to that in the AD-MCI group. The 24-h and daytime CV of SBP and ambulatory pulse pressure were significantly and negatively correlated with memory score. The average 24-h and average daytime SBP level and CV of SBP, daytime CV of diastolic BP (DBP), and 24-h, daytime, and night-time ambulatory pulse pressure were significantly and negatively correlated with language score. The average 24-h SBP level, daytime CV of SBP, and 24-h, daytime, and night-time ambulatory pulse pressure were significantly and negatively correlated with attention score. Further analysis indicated that daytime CV of SBP as well as age and course of disease were the independent influencing factors of language. Age was also the independent influencing factor of memory and attention of patients with AD. T-tau level in CSF in the AD-D group was significantly higher than that in the AD-MCI group, but the levels of Aβ1−42, P-tau, and T-tau in CSF were not correlated with 24-h ambulatory BP variables.

Conclusion

Daytime CV of SBP was the independent influencing factor of language in patients with AD. The AD-D patients had significantly severe neurodegeneration than AD-MCI patients, which was, however, not through the influence of 24-h ambulatory BP variables on neuropathological biomarkers of AD.

Application of curcumin nanoformulations in Alzheimer's disease: prevention, diagnosis and treatment

Objectives: Alzheimer's disease (AD) is a serious neurodegenerative disease. Although many therapeutic strategies have been studied, their clinical applications are immature. Moreover, these methods can only alleviate symptoms rather than cure it, posing a challenge to brain health in older adults worldwide. Curcumin (CUR) is a very promising natural compound for nerve protection and treatment. It can prevent and treat AD, and on the other hand, its fluorescence properties can be used in the diagnosis of AD. However, CUR is characterized by very low water solubility, fluid instability, rapid metabolism, low bioavailability and difficulty in penetrating the biological barriers, which limit its application. Nanocarriers are a potential material to improve the biocompatibility of CUR and its ability to cross biological barriers. Therefore, delivering CUR by nanocarriers is an effective method to achieve better efficacy. Methods: In this review, the preventive, therapeutic and diagnostic effects of CUR nanoformulations on AD, as well as various patents, clinical trials and experimental research progress in this field are discussed. The aim is to provide detailed reference and practical suggestions for future research. Results: CUR has a variety of pharmacological activities in the prevention and treatment of AD, and its nanoformulation can effectively improve solubility, bioavailability and the ability to penetrate the blood-brain barrier. Significant benefits have been observed in the current study. Discussion: CUR formulations have a good prospect in the prevention, diagnosis and treatment of AD, but the safety and principle of its administration need more detailed study in the future.

Alteration of miRNAs in Small Neuron-Derived Extracellular Vesicles of Alzheimer's Disease Patients and the Effect of Extracellular Vesicles on Microglial Immune Responses

Alzheimer's disease (AD) is one of the most severe neurodegenerative diseases observed in the elderly population. Although the hallmarks of AD have been identified, the methods for its definitive diagnosis and treatment are still lacking. Extracellular vesicles (EVs) have become a promising source for biomarkers since the identification of their content. EVs are released from multiple cell types and, when released from neurons, they pass from the brain to the blood with their cargo molecules. Hence, neuron-specific EV-resident microRNAs (miRNAs) are promising biomarkers for diagnosis of AD. This study aimed to identify altered miRNA content in small neuron-derived extracellular vesicles (sNDEVs) isolated from AD patients and healthy individuals. Furthermore, we examined the role of sNDEV-resident miRNAs in neuron-glia cellular interaction to understand their role in AD propagation. We identified 10 differentially expressed miRNAs in the sNDEVs of patients via next-generation sequencing and validated the most dysregulated miRNA, let-7e, with qRT-PCR. Let-7e was significantly increased in the sNDEVs of AD patients compared with those of healthy controls in a larger cohort. First, we evaluated the diagnostic utility of let-7e via ROC curve analysis, which revealed an AUC value of 0.9214. We found that IL-6 gene expression was increased in human microglia after treatment with sNDEVs of AD patients with a high amount of let-7e. Our study suggests that sNDEV-resident let-7e is a potential biomarker for AD diagnosis, and that AD patient-derived sNDEVs induce a neuroinflammatory response in microglia.

Fatty Acid-Binding Protein 7 (FABP-7), Glutamic Acid and Neurofilament Light Chain (NFL) as Potential Markers of Neurodegenerative Disorders in Psoriatic Patients-A Pilot Study

Psoriasis and neurodegenerative diseases (NDs) are important medical, social and economic issues. The possible relationship of psoriasis and NDs has not been established yet. This study involved 60 patients with plaque-type psoriasis. Serum concentrations of fatty acid-binding protein 7 (FABP-7), glutamic acid (GA) and neurofilament light chain (NFL), which have been hardly studied in psoriasis before, were measured by ELISA before and after 12 weeks of treatment with acitretin or methotrexate. The concentration of FABP-7 and NFL in patients before the treatment was significantly higher than in the controls (p < 0.01, p < 0.001, respectively). After the treatment their concentration decreased, although FABP-7 did so insignificantly. The concentration of GA did not differ significantly between patients and controls and before and after the treatment but we found its negative correlation with CRP (p < 0.05). The duration of psoriasis does not seem to directly affect the risk of neurodegeneration and the severity only in patients with worse skin condition. Elevated FABP-7 and NFL, which are present in the brain, may be considered as potential indicators of NDs development in psoriatics, although it surely requires further research. GA might correspond with neuroinflammation in psoriasis. Systemic antipsoriatic therapy could be studied in order to improve cognitive impairment through lowering NDs biomarkers in some cases.

Genetic Inactivation of Free Fatty Acid Receptor 3 Impedes Behavioral Deficits and Pathological Hallmarks in the APPswe Alzheimer's Disease Mouse Model

The free fatty acid FFA3 receptor (FFA3R) belongs to the superfamily of G-protein-coupled receptors (GPCRs). In the intestine and adipose tissue, it is involved in the regulation of energy metabolism, but its function in the brain is unknown. We aimed, first, to investigate the expression of the receptor in the hippocampus of Alzheimer disease (AD) patients at different stages of the disease and, second, to assess whether genetic inactivation of the Ffar3 gene could affect the phenotypic features of the APP_swe mouse model. The expression of transcripts for FFA receptors in postmortem human hippocampal samples and in the hippocampus of wild-type and transgenic mice was analyzed by RT-qPCR. We generated a double transgenic mouse, FFA3R^−/−/APP_swe, to perform cognition studies and to assess, by immunoblotting Aβ and tau pathologies and the differential expression of synaptic plasticity-related proteins. For the first time, the occurrence of the FFA3R in the human hippocampus and its overexpression, even in the first stages of AD, was demonstrated. Remarkably, FFA3R^−/−/APP_swe mice do not have the characteristic memory impairment of 12-month-old APP_swe mice. Additionally, this newly generated transgenic line does not develop the most important Alzheimer’s disease (AD)-related features, such as amyloid beta (Aβ) brain accumulations and tau hyperphosphorylation. These findings are accompanied by increased levels of the insulin-degrading enzyme (IDE) and lower activity of the tau kinases GSK3β and Cdk5. We conclude that the brain FFA3R is involved in cognitive processes and that its inactivation prevents AD-like cognitive decline and pathological hallmarks.

Evaluation of Utilizing the Distinct Genes as Predictive Biomarkers in Late-Onset Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease that is characterized by a devastating decline in cognitive activities among all types of dementia, and it severely affects the quality of life. Late-onset AD (LOAD) occurs after the age of 65 years and develops sporadically. Although aging comes first along the main risk factors underlying LOAD, disease-causing susceptibility genes have been associated with disease pathogenesis. In our study, we included the genes PARP1 , POLB , HTRA2 , SLC1A2 , HS1BP3 , and DRD3 to be investigated in LOAD patients based on their expression levels. Within this framework, we aimed to determine the possible functions of these genes in the pathophysiology of the disease. We investigated whether the utilization of these genes as biomarkers in the early diagnosis of LOAD may help the treatment scheme to be applied in the clinic. We involved 50 individuals in the study and collected peripheral blood samples from the patients and control groups for molecular genetic analysis. Subsequently, RNA was extracted from the peripheral blood samples, and expression analyzes were performed using qualitative reverse transcription polymerase chain reaction. The results obtained were evaluated by using proper statistical methods. Our results demonstrated that there was no difference between patient and control groups in terms of HTRA2 , DRD3 , HS1BP3 , and POLB genes. The expression levels of the SLC1A2 and PARP1 genes were significantly lower in the patient group compared with the control group. In conclusion, we presume that the PARP1 and SLC1A2 genes can be utilized as molecular biomarkers for LOAD.

Biomarkers used in Alzheimer's disease diagnosis, treatment, and prevention

Alzheimer's disease (AD), being the number one in terms of dementia burden, is an insidious age-related neurodegenerative disease and is presently considered a global public health threat. Its main histological hallmarks are the Aβ senile plaques and the P-tau neurofibrillary tangles, while clinically it is marked by a progressive cognitive decline that reflects the underlying synaptic loss and neurodegeneration. Many of the drug therapies targeting the two pathological hallmarks namely Aβ and P-tau have been proven futile. This is probably attributed to the initiation of therapy at a stage where cognitive alterations are already obvious. In other words, the underlying neuropathological changes are at a stage where these drugs lack any therapeutic value in reversing the damage. Therefore, there is an urgent need to start treatment in the very early stage where these changes can be reversed, and hence, early diagnosis is of primordial importance. To this aim, the use of robust and informative biomarkers that could provide accurate diagnosis preferably at an earlier phase of the disease is of the essence. To date, several biomarkers have been established that, to a different extent, allow researchers and clinicians to evaluate, diagnose, and more specially exclude other related pathologies. In this study, we extensively reviewed data on the currently explored biomarkers in terms of AD pathology-specific and non-specific biomarkers and highlighted the recent developments in the diagnostic and theragnostic domains. In the end, we have presented a separate elaboration on aspects of future perspectives and concluding remarks.

Neurogranin as a Reliable Biomarker for Synaptic Dysfunction in Alzheimer's Disease

(1) Background: Neurogranin is a post-synaptic protein expressed in the neurons of the hippocampus and cerebral cortex. It has been recently proposed as a promising biomarker of synaptic dysfunction, especially in Alzheimer's disease (AD). However, more efforts are needed before introducing it in clinical practice, including the definition of its reference interval (RI). The aim of the study was to establish the RI of cerebrospinal fluid (CSF) neurogranin levels in controls and individuals with non-neurodegenerative neurological diseases; (2) We included a total of 136 individuals that were sub-grouped as follows: AD patients (n = 33), patients with non-neurodegenerative neurological diseases (n = 70) and controls (33). We measured CSF neurogranin levels by a commercial ELISA kit. CSF RI of neurogranin was calculated by a robust method; (3) Results: AD patients showed increased levels of neurogranin. We also found that neurogranin was significantly correlated with T-tau, P-tau and mini mental state examination in AD patients. The lower and upper reference limits of the RI were 2.9 (90%CI 0.1-10.8) and 679 (90%CI 595-779), respectively; (4) Conclusion: This is the first study establishing the RI of CSF neurogranin.

Novel Multitarget Hydroxamic Acids with a Natural Origin CAP Group against Alzheimer's Disease: Synthesis, Docking and Biological Evaluation

Hydroxamic acids are one of the most promising and actively studied classes of chemical compounds in medicinal chemistry. In this study, we describe the directed synthesis and effects of HDAC6 inhibitors. Fragments of adamantane and natural terpenes camphane and fenchane, combined with linkers of various nature with an amide group, were used as the CAP groups. Accordingly, 11 original target compounds were developed, synthesized, and exposed to in vitro and in vivo biological evaluations, including in silico methods. In silico studies showed that all synthesized compounds were drug-like and could penetrate through the blood-brain barrier. According to the in vitro testing, hydroxamic acids 15 and 25, which effectively inhibited HDAC6 and exhibited anti-aggregation properties against β-amyloid peptides, were chosen as the most promising substances to study their neuroprotective activities in vivo. All in vivo studies were performed using 5xFAD transgenic mice simulating Alzheimer's disease. In these animals, the Novel Object Recognition and Morris Water Maze Test showed that the formation of hippocampus-dependent long-term episodic and spatial memory was deteriorated. Hydroxamic acid 15 restored normal memory functions to the level observed in control wild-type animals. Notably, this effect was precisely associated with the ability to restore lost cognitive functions, but not with the effect on motor and exploratory activities or on the level of anxiety in animals. Conclusively, hydroxamic acid 15 containing an adamantane fragment linked by an amide bond to a hydrocarbon linker is a possible potential multitarget agent against Alzheimer's disease.

Microfluidic Platforms to Unravel Mysteries of Alzheimer's Disease: How Far Have We Come?

Alzheimer’s disease (AD) is a significant health concern with enormous social and economic impact globally. The gradual deterioration of cognitive functions and irreversible neuronal losses are primary features of the disease. Even after decades of research, most therapeutic options are merely symptomatic, and drugs in clinical practice present numerous side effects. Lack of effective diagnostic techniques prevents the early prognosis of disease, resulting in a gradual deterioration in the quality of life. Furthermore, the mechanism of cognitive impairment and AD pathophysiology is poorly understood. Microfluidics exploits different microscale properties of fluids to mimic environments on microfluidic chip-like devices. These miniature multichambered devices can be used to grow cells and 3D tissues in vitro, analyze cell-to-cell communication, decipher the roles of neural cells such as microglia, and gain insights into AD pathophysiology. This review focuses on the applications and impact of microfluidics on AD research. We discuss the technical challenges and possible solutions provided by this new cutting-edge technique to understand disease-associated pathways and mechanisms.

Curcumin Alleviates Aβ42-Induced Neuronal Metabolic Dysfunction via the Thrb/SIRT3 Axis and Improves Cognition in APPTG Mice

Curcumin has been reported to have a therapeutic effect on Alzheimer's disease (AD), but the specific mechanism remains to be elucidated. In the present research, we aimed to investigate the effect and molecular mechanism of curcumin on AD. Mouse primary hippocampal neuron cells were treated with various concentrations of beta-amyloid 42 (Aβ₄₂) and the results found that Aβ₄₂ inhibited cell viability in a dose-dependent manner. Compared with 50 ng/mL Aβ₄₂, 500 ng/mL Aβ₄₂ could further promote cell apoptosis, reduce the ratio of Nicotinamide adenine dinucleotide (NAD(+))/Nicotinamide adenine diphosphate hydride (NADH) and Adenosine 5'-triphosphate (ATP) level, and inhibit Sirtuins 3 (SIRT3) deacetylation activity and protein expression of Thyroid hormone receptor beta (Thrb) and SIRT3. Hence, 500 ng/mL Aβ₄₂ was used to establish a cell model of AD. Curcumin significantly reversed the inhibitory effects of Aβ₄₂ on cell viability, SIRT3 deacetylation activity, the ratio of NAD⁺/NADH, ATP level and the protein expression of Thrb and SIRT3, and the promotive effect on apoptosis. ChIPBase was used to predict the binding region of Thrb and SIRT3. Dual luciferase reporter gene and Chromatin immune precipitation (ChIP) assays were employed to verify the relationship between Thrb and promoter of SIRT3 mRNA. Overexpression of Thrb recovered Aβ₄₂ induced metabolic dysfunction, while Thrb silence aggravated Aβ₄₂ induced metabolic dysfunction. Moreover, Thrb silence or 3-TYP (a selective inhibitor of SIRT3) treatment abolished the amelioration of curcumin on Aβ₄₂ induced metabolic dysfunction. Additionally, curcumin attenuated memory deficits in Amyloid precursor protein transgenic (APP_TG) mice. Collectively, curcumin alleviated Aβ₄₂-induced neuronal metabolic dysfunction through increasing Thrb expression and SIRT3 activity and improved cognition in APP_TG mice.

Alzheimer's disease neuropathology is exacerbated following traumatic brain injury. Neuroprotection by co-administration of nanowired mesenchymal stem cells and cerebrolysin with monoclonal antibodies to amyloid beta peptide

Military personnel are prone to traumatic brain injury (TBI) that is one of the risk factors in developing Alzheimer's disease (AD) at a later stage. TBI induces breakdown of the blood-brain barrier (BBB) to serum proteins into the brain and leads to extravasation of plasma amyloid beta peptide (ΑβP) into the brain fluid compartments causing AD brain pathology. Thus, there is a need to expand our knowledge on the role of TBI in AD. In addition, exploration of the novel roles of nanomedicine in AD and TBI for neuroprotection is the need of the hour. Since stem cells and neurotrophic factors play important roles in TBI and in AD, it is likely that nanodelivery of these agents exert superior neuroprotection in TBI induced exacerbation of AD brain pathology. In this review, these aspects are examined in details based on our own investigations in the light of current scientific literature in the field. Our observations show that TBI exacerbates AD brain pathology and TiO₂ nanowired delivery of mesenchymal stem cells together with cerebrolysin-a balanced composition of several neurotrophic factors and active peptide fragments, and monoclonal antibodies to amyloid beta protein thwarted the development of neuropathology following TBI in AD, not reported earlier.