Aβ Deposition Research Articles

Exploring the Potential of Herbal Compounds as Autophagy Modulators in Alzheimer's Disease: A Comprehensive Review

Abstract: Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that causes atrophy of brain cells, leading to their death, and has become a leading cause of death in aging populations worldwide. AD is characterized by β-amyloid (Aβ) deposition and tau phosphorylation in neural tissues, but the precise pathophysiology of the disease is still obscure. Autophagy is an evolutionarily targeted mechanism that is necessary for the elimination of neuronal and glial misfolded proteins as well as proteins. It also plays an essential role in synaptic plasticity. The aberrant autophagy primarily influences the process of aging and neurodegeneration. Autophagy significantly influences how Aβ and tau function physiologically, therefore, atypical autophagy is expected to perform an important role in Aβ deposition and tau phosphorylation characteristic in the development of AD. Bioactive phytoconstituents could majorly contribute as a natural yet effective alternative approach to slow down the progression of neurodegeneration and promote the active aging process in elderly patients. Over the recent years, it is well evidenced that different secondary metabolites including polyphenols, alkaloids, terpenes, and phenols exhibited neuroprotective effects, and attenuated brain damage, and cognitive impairment in vitro as well as in vivo. Additionally, the underlying mechanism of action shared by them is the regulation of competent autophagy via the removal of aggregated protein and mitochondrial dysfunction. The present article is structured as a reference for researchers keen to investigate and assess the new natural compound-mediated therapeutic approach for AD treatment through the modulation of autophagy.

Synergistic association of Aβ and tau pathology with cortical neurophysiology and cognitive decline in asymptomatic older adults.

Animal and computational models of Alzheimer's disease (AD) indicate that early amyloid-β (Aβ) deposits drive neurons into a hyperactive regime, and that subsequent tau depositions manifest an opposite, suppressive effect as behavioral deficits emerge. Here we report analogous changes in macroscopic oscillatory neurophysiology in the human brain. We used positron emission tomography and task-free magnetoencephalography to test the effects of Aβ and tau deposition on cortical neurophysiology in 104 cognitively unimpaired older adults with a family history of sporadic AD. In these asymptomatic individuals, we found that Aβ depositions colocalize with accelerated neurophysiological activity. In those also presenting medial-temporal tau pathology, linear mixed effects of Aβ and tau depositions indicate a shift toward slower neurophysiological activity, which was also linked to cognitive decline. We conclude that early Aβ and tau depositions relate synergistically to human cortical neurophysiology and subsequent cognitive decline. Our findings provide insight into the multifaceted neurophysiological mechanisms engaged in the preclinical phases of AD.

Chronic stress induces insulin resistance and enhances cognitive impairment in AD

BackgroundChronic stress can induce the cognitive impairment, and even promote the occurrence and development of Alzheimer's disease (AD). Evidence has suggested that chronic stress impacts on glucose metabolism, and both of these have been implicated in AD. Here we focused on the effect of insulin resistance in glucose metabolism, and further evaluated the changes in cognition and pathology. MethodsMale 9-month-old wild-type and APP/PS1 mice were randomly divided into 4 groups. Mice in the chronic unpredictable mild stress (CUMS) groups were exposed for 4 weeks. Homeostatic Model Assessment (HOMA) was utilized to evaluate insulin sensitivity. A total of eighty-four genes related to the insulin signaling pathway were examined for rapid screening. Additionally, the phosphorylated protein expressions of insulin receptors (IR), IR substrate 1 (IRS1), c-Jun N-terminal kinase (JNK), and amyloid were detected in the hippocampus. Cognitive function was assessed through ethological methods. Cognitive function was assessed using both the Morris water maze (MWM) and the Passive avoidance test (PAT). ResultsFour weeks of CUMS exposure significantly increased the HOMA value, indicating reduced insulin sensitivity. The gene expressions of Insr and Lipe were downregulated. Additionally, the analysis revealed a significant interaction between the genotype (wild-type vs. APP/PS1) and CUMS treatment on the phosphorylated protein expressions of insulin receptor substrate 1 (IRS1). Specifically, CUMS exposure increased the inhibitory phosphorylation site (IRS1-pSer636) and decreased the excitatory phosphorylation site (IRS1-pTyr465) in the post-insulin receptor signaling pathway within the hippocampus of both wild-type and APP/PS1 mice. Moreover, CUMS exposure induced and exacerbated cognitive impairments in both wild-type and APP/PS1 mice, as assessed by the Morris water maze (MWM) and Passive avoidance test (PAT). However, there was no significant effect of CUMS on senile plaque deposition or levels of Aβ42 and Aβ40 in wild-type mice. ConclusionsChronic stress significantly affects hippocampal cognitive function through insulin resistance and exacerbates AD pathology. This study reveals the complex relationship between chronic stress, insulin resistance, and AD, providing new insights for developing interventions targeting chronic stress and insulin resistance.

ZiBu PiYin recipe regulates central and peripheral Aβ metabolism and improves diabetes-associated cognitive decline in ZDF rats

Ethnopharmacological relevanceCognitive impairment caused by central neuropathy in type 2 diabetes mellitus (T2DM), namely diabetes-associated cognitive decline (DACD), is one of the common complications in patients with T2DM. Studies have shown that brain β-amyloid (Aβ) deposition is a typical pathological change in patients with DACD, and that there is a close relationship between intestinal microorganisms and cognitive impairment. However, the specific mechanism(s) of alteration in Aβ metabolism in DACD, and of the correlation between Aβ metabolism and intestinal microorganisms remain unknown. Aim of the studyRevealing the mechanism of ZBPYR regulating Aβ metabolism and providing theoretical basis for clinical evaluation and diagnosis of DACD. Materials and methodsWe characterized Aβ metabolism in the central and peripheral tissues of Zucker diabetic fatty (ZDF) rats with DACD, and then explored the preventive and therapeutic effects of ZiBu PiYin Recipe (ZBPYR). Specifically, we assessed these animals for the formation, transport, and clearance of Aβ; the morphological structure of the blood-brain barrier (BBB); and the potential correlation between Aβ metabolism and intestinal microorganisms. ResultsZBPYR provided improvements in the structure of the BBB, attenuation of Aβ deposition in the central and peripheral tissues, and a delay in the development of DACD by improving the expression of Aβ production, transport, and clearance related protein in ZDF rats. In addition, ZBPYR improved the diversity and composition of intestinal microorganisms, decreased the abundance of Coprococcus, a bacterium closely related to Aβ production, and up regulate the abundance of Streptococcus, a bacterium closely related to Aβ clearance. ConclusionThe mechanism of ZBPYR ability to ameliorate DACD may be closely related to changes in the intestinal microbiome.

Biofilm-camouflaged Prussian blue synergistic mitochondrial mass enhancement for Alzheimer's disease based on Cu2+ chelation and photothermal therapy

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases characterized by cognitive and memory impairment. Metal ion imbalance and Mitochondrial dysfunction, leading to abnormal aggregation of β-amyloid protein (Aβ), are key factors in the pathogenesis of AD. Therefore, we designed a composite nanometer system of red blood cell (RBC) membranes-encapsulated Prussian blue nanoparticles (PB/RBC). Prussian blue nanoparticles (PBNPs) can chelate Cu2+ and reduce reactive oxygen species (ROS). The RBC membranes are a kind of natural long-lasting circulating carrier. At the same time, through NIR irradiation, the excellent photothermal ability of PBNPs can also temporarily open the blood-brain barrier (BBB), enhance the transmission efficiency of PB/RBC across the BBB, and depolymerize the formed Aβ deposits, thereby achieving the optimal therapeutic effect. In vitro and in vivo studies demonstrated that PB/RBC could inhibit Cu2+-induced Aβ monomers aggregation, eliminate the deposition of Aβ plaques, improve the quality of mitochondria, restore the phagocytic function of microglia, alleviate neuroinflammation in APP/PS1 mice, and repair memory damage. In conclusion, our biofilm-camouflaged nano-delivery system provides significant neuroprotection by inhibiting Cu2+-induced Aβ monomers aggregation, photothermally depolymerizing Aβ fibrils and reducing the level of ROS, thus effectively ameliorating and treating AD.

Impact of amyloid and cardiometabolic risk factors on prognostic capacity of plasma neurofilament light chain for neurodegeneration

BackgroundPlasma neurofilament light chain (NfL) is a blood biomarker of neurodegeneration, including Alzheimer’s disease. However, its usefulness may be influenced by common conditions in older adults, including amyloid-β (Aβ) deposition and cardiometabolic risk factors like hypertension, diabetes mellitus (DM), impaired kidney function, and obesity. This longitudinal observational study using the Alzheimer’s Disease Neuroimaging Initiative cohort investigated how these conditions influence the prognostic capacity of plasma NfL.MethodsNon-demented participants (cognitively unimpaired or mild cognitive impairment) underwent repeated assessments including the Alzheimer’s Disease Assessment Scale-Cognitive subscale (ADAS-Cog) scores, hippocampal volumes, and white matter hyperintensity (WMH) volumes at 6- or 12-month intervals. Linear mixed-effect models were employed to examine the interaction between plasma NfL and various variables of interest, such as Aβ (evaluated using Florbetapir positron emission tomography), hypertension, DM, impaired kidney function, or obesity.ResultsOver a mean follow-up period of 62.5 months, participants with a mean age of 72.1 years (n = 720, 48.8% female) at baseline were observed. Higher plasma NfL levels at baseline were associated with steeper increases in ADAS-Cog scores and WMH volumes, and steeper decreases in hippocampal volumes over time (all p-values < 0.001). Notably, Aβ at baseline significantly enhanced the association between plasma NfL and longitudinal changes in ADAS-Cog scores (p-value 0.005) and hippocampal volumes (p-value 0.004). Regarding ADAS-Cog score and WMH volume, the impact of Aβ was more prominent in cognitively unimpaired than in mild cognitive impairment. Hypertension significantly heightened the association between plasma NfL and longitudinal changes in ADAS-Cog scores, hippocampal volumes, and WMH volumes (all p-values < 0.001). DM influenced the association between plasma NfL and changes in ADAS-Cog scores (p-value < 0.001) without affecting hippocampal and WMH volumes. Impaired kidney function did not significantly alter the association between plasma NfL and longitudinal changes in any outcome variables. Obesity heightened the association between plasma NfL and changes in hippocampal volumes only (p-value 0.026).ConclusionThis study suggests that the prognostic capacity of plasma NfL may be amplified in individuals with Aβ or hypertension. This finding emphasizes the importance of considering these factors in the NfL-based prognostic model for neurodegeneration in non-demented older adults.

Zeaxanthin and Lutein Ameliorate Alzheimer's Disease-like Pathology: Modulation of Insulin Resistance, Neuroinflammation, and Acetylcholinesterase Activity in an Amyloid-β Rat Model.

Alzheimer's disease (AD) is characterized by impaired insulin/insulin-like growth factor-1 signaling in the hippocampus. Zeaxanthin and lutein, known for their antioxidant and anti-inflammatory properties, have been reported to protect against brain damage and cognitive decline. However, their mechanisms related to insulin signaling in AD remain unclear. This study investigated the efficacy and mechanisms of zeaxanthin, lutein, and resveratrol in modulating an AD-like pathology in an amyloid-β rat model. Rats were administered hippocampal infusions of 3.6 nmol/day amyloid-β (Aβ)(25-35) for 14 days to induce AD-like memory deficits (AD-CON). Normal control rats received Aβ(35-25) (Normal-CON). All rats had a high-fat diet. Daily, AD rats consumed 200 mg/kg body weight of zeaxanthin (AD-ZXT), lutein (AD-LTN), and resveratrol (AD-RVT; positive-control) or resistant dextrin as a placebo (AD-CON) for eight weeks. The AD-CON rats exhibited a higher Aβ deposition, attenuated hippocampal insulin signaling (reduced phosphorylation of protein kinase B [pAkt] and glycogen synthase kinase-3β [pGSK-3β]), increased neuroinflammation, elevated acetylcholinesterase activity, and memory deficits compared to the Normal-CON group. They also showed systemic insulin resistance and high hepatic glucose output. Zeaxanthin and lutein prevented memory impairment more effectively than the positive-control resveratrol by suppressing acetylcholinesterase activity, lipid peroxidation, and pro-inflammatory cytokines (TNF-α, IL-1β). They also potentiated hippocampal insulin signaling and increased brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CTNF) mRNA expression to levels comparable to the Normal-CON rats. Additionally, zeaxanthin and lutein improved glucose disposal, reduced hepatic glucose output, and normalized insulin secretion patterns. In conclusion, zeaxanthin and lutein supplementation at doses equivalent to 1.5-2.0 g daily in humans may have practical implications for preventing or slowing human AD progression by reducing neuroinflammation and maintaining systemic and central glucose homeostasis, showing promise even when compared to the established neuroprotective compound resveratrol. However, further clinical trials are needed to evaluate their efficacy and safety in human populations.

Convergent Multimodal Imaging Abnormalities in the Dorsal Precuneus in Subjective Cognitive Decline.

A range of imaging modalities have reported Alzheimer's disease-related abnormalities in individuals experiencing subjective cognitive decline (SCD). However, there has been no consistent local abnormality identified across multiple neuroimaging modalities for SCD. We aimed to investigate the convergent local alterations in amyloid-β (Aβ) deposition, glucose metabolism, and resting-state functional MRI (RS-fMRI) metrics in SCD. Fifty SCD patients (66.4±5.7 years old, 19 men [38%]) and 15 normal controls (NC) (66.3±4.4 years old, 5 men [33.3%]) were scanned with both [18F]-florbetapir PET and [18F]-fluorodeoxyglucose PET, as well as simultaneous RS-fMRI from February 2018 to November 2018. Voxel-wise metrics were retrospectively analyzed, including Aβ deposition, glucose metabolism, amplitude of low frequency fluctuation (ALFF), regional homogeneity (ReHo), and degree centrality(DC). The SCD group showed increased Aβ deposition and glucose metabolism (p < 0.05, corrected), as well as decreased ALFF, ReHo, and DC (p < 0.05, uncorrected) in the left dorsal precuneus (dPCu). Furthermore, the dPCu illustrated negative resting-state functional connectivity with the default mode network. Regarding global Aβ deposition positivity, the Aβ deposition in the left dPCu showed a gradient change, i.e., Aβ positive SCD > Aβ negative SCD > Aβ negative NC. Additionally, both Aβ positive SCD and Aβ negative SCD showed increased glucose metabolism and decreased RS-fMRI metrics in the dPCu. The dorsal precuneus, an area implicated in early AD, shows convergent neuroimaging alterations in SCD, and might be more related to other cognitive functions (e.g., unfocused attention) than episodic memory.

Sarcopenia is a predictor for Alzheimer’s continuum and related clinical outcomes

Low body mass index is closely related to a high risk of Alzheimer’s disease (AD) and related biomarkers including amyloid-β (Aβ) deposition. However, the association between sarcopenia and Aβ-confirmed AD remains controversial. Therefore, we investigated the relationship between sarcopenia and the AD continuum. We explored sarcopenia’s association with clinical implications of participants on the AD continuum. We prospectively enrolled 142 participants on the AD continuum (19 with preclinical AD, 96 with mild cognitive impairment due to AD, and 28 with AD dementia) and 58 Aβ-negative cognitively unimpaired participants. Sarcopenia, assessed using dual-energy X-ray absorptiometry and hand grip measurements, was considered a predictor. AD continuum, defined by Aβ deposition on positron emission tomography served as an outcome. Clinical severity in participants on the AD continuum assessed using hippocampal volume, Mini-Mental State Examination (MMSE), Seoul Verbal Learning Test (SVLT), and Clinical Dementia Rating Scale Sum of Boxes Scores (CDR-SOB) were also considered an outcome. Sarcopenia (odds ratio = 4.99, p = 0.004) was associated independently with the AD continuum after controlling for potential confounders. Moreover, sarcopenia was associated with poor downstream imaging markers (decreased hippocampal volume, β = − 0.206, p = 0.020) and clinical outcomes (low MMSE, β = − 1.364, p = 0.025; low SVLT, β = − 1.077, p = 0.025; and high CDR-SOB scores, β = 0.783, p = 0.022) in participants on the AD continuum. Sarcopenia was associated with the AD continuum and poor clinical outcome in individuals with AD continuum. Therefore, our results provide evidence for future studies to confirm whether proper management of sarcopenia can effective strategies are required for sarcopenia management to prevent the AD continuum and its clinical implications.

Synergistic Role of Aerobic Training and Resveratrol on AMPK/PGC1-α/SIRT1 Pathway in the Hippocampus of Rats with Alzheimer's Disease

Background: Alzheimer's disease symptoms indicate that increased Aβ leads to central nervous system dysfunction. Exercise reduces Aβ deposition through the AMPK signaling pathway. Additionally, resveratrol (RSV) has neuroprotective effects related to cognitive decline. Objectives: This study investigated the effects of aerobic training and RSV on the AMPK/PGC-1α/SIRT1 pathway in the hippocampus of Alzheimer's rats. Methods: Thirty-five male Wistar rats were divided into five groups: Normal (NO), Alzheimer's (AD), Alzheimer's-training (ADT), Alzheimer's-resveratrol (ADRSV), and Alzheimer's-training-resveratrol (ADTRSV). The supplement groups received 20 mg of RSV (per kg of body weight) orally during the intervention period. The aerobic exercise program, which included running on a treadmill at speeds of 6 - 18 meters per minute, was performed 5 days a week for eight weeks. Results: Alzheimer's induction caused a significant decrease in the expression of AMPK/PGC-1α/SIRT1 (P = 0.0001). Exercise and RSV significantly increased the expression of AMPK/PGC-1α/SIRT1 in AD rats (P &lt; 0.05). Additionally, significant increases in the expression of AMPK, PGC-1α, and SIRT1 were observed in the ADTRSV group compared to the ADT group (P = 0.034, P = 0.020, and P = 0.038, respectively) and ADRSV (P = 0.026, P = 0.021, and P = 0.021). Conclusions: AD induction was associated with decreased AMPK/PGC-1α/SIRT1 expression. Aerobic exercise and RSV consumption can reverse this decrease. Given the crucial role of this signaling pathway in hippocampal function, alterations in these indicators following physical activity and RSV use may partially mitigate Alzheimer's disease complications.

Agonistes des récepteurs GLP-1 dans la maladie d’Alzheimer : Potentiel thérapeutique et mécanismes d’action

Alzheimer's disease (AD) is a debilitating neurodegenerative disorder characterized by progressive cognitive decline and neuronal dysfunction. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs), originally developed for the treatment of type 2 diabetes, have demonstrated promising neuroprotective effects. This review aims to evaluate the effects and underlying mechanisms of GLP-1 RAs in the context of AD. A comprehensive search of databases yielded 622 articles, from which studies met the predefined inclusion criteria and were subjected to detailed analysis, 29 articles were deemed appropriate for analysis. The results indicate that GLP-1 RAs can significantly reduce amyloid-beta (Aβ) deposition and phosphorylated tau levels in the brains of AD patients. These neuroprotective effects are attributed to multiple synergistic mechanisms, including the enhancement of neuronal survival, reduction of oxidative stress, and attenuation of neuroinflammation. This review underscores the importance of further research to fully elucidate the mechanisms of GLP-1 RAs and their potential as a therapeutic strategy for AD.

Abstract P233: Amyloid Beta Plaque Deposits Co-Localize with Endothelial Cells in the Hippocampus of Female APPswe/PSEN1dE9 Mice During the Onset of Amyloid Pathology

Increasing evidence shows that cardiovascular diseases are associated with an increased risk of cognitive impairment and Alzheimer’s diseases (AD). It is unknown whether systemic vascular dysfunction occurs prior to the development of AD, if this occurs in a sex-dependent manner, or whether endothelial cells play a role in the deposition of amyloid beta (Aβ) peptides. We hypothesized that female mice present with an exacerbated formation of Aβ peptides, and vascular dysfunction would occur during the onset of amyloid pathology, thus escalating its progression. To test this hypothesis, we used a double transgenic mouse model of early onset AD (APPswe/PSEN1dE9) prior to the onset of amyloid pathology (3 months of age) and during the onset of amyloid pathology (7 months of age). Immunofluorescence was performed in the hippocampus stained with Aβ 1-42 and CD31 antibodies. High resolution images were acquired on the confocal microscope. Acetylcholine-induced relaxation (1pM-30µM) was evaluated in mesenteric resistance arteries (MRA), and the data analyzed as non-linear curve regression and maximum effect (Emax). The statistical analysis was performed using Student’s t test, or two-way ANOVA followed by Tukey post-hoc ( p &lt;0.05*). We observed that during the onset of amyloid pathology (7-months-old), there was elevated Aβ deposition which co-localized with endothelial cells in the hippocampus from female but not male APP/PS1 mice [females colocalization rate (%): control 12.9 ± 2.0 vs . APP/PS1 25.1 ± 7.8, n=4; males colocalization rate (%): control 23.2 ± 6.5 vs. APP/PS1 15.3 ± 3.3, n=4]. In addition, the 7-month-old female APP/PS1 mice showed an exacerbated endothelium-dependent relaxation compared to the 3-month-old group (female APP/PS1 7-month-old ACh Emax: 97.1 ± 1.6*%, n=4 vs. 3-month-old ACh Emax: 70.1 ± 8.3%, n=6). Furthermore, endothelial dysfunction occurred prior to the onset of amyloid pathology irrespective of sex. Overall, these data showed that the endothelial dysfunction prior to the onset of amyloid pathology may be an early marker of AD. Further, a greater burden of Aβ formation in hippocampal endothelial cells from female but not male APP/PS1 mice may be associated with vascular abnormalities and dysfunction.

Cinnamic Acid Derivatives: Recent Discoveries and Development Strategies for Alzheimer's Disease.

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder that leads to cognitive decline and memory impairment. It is characterized by the accumulation of Amyloid-beta (Aβ) plaques, the abnormal phosphorylation of tau protein forming neurofibrillary tangles, and is often accompanied by neuroinflammation and oxidative stress, which contribute to neuronal loss and brain atrophy. At present, clinical anti-AD drugs are mostly single-target, improving the cognitive ability of AD patients, but failing to effectively slow down the progression of AD. Therefore, research on effective multi-target drugs for AD has become an urgent problem to address. The main derivatives of hydroxycinnamic acid, caffeic acid, and ferulic acid, are widely present in nature and have many pharmacological activities, such as antimicrobial, antioxidant, anti-inflammatory, neuroprotective, anti-Aβ deposition, and so on. The occurrence and development of AD are often accompanied by pathologies, such as oxidative stress, neuroinflammation, and Aβ deposition, suggesting that caffeic acid and ferulic acid can be used in the research on anti-AD drugs. Therefore, in this article, we have summarized the multi-target anti-AD derivatives based on caffeic acid and ferulic acid in recent years, and discussed the new design direction of cinnamic acid derivatives as backbone compounds. It is hoped that this review will provide some useful strategies for anti-AD drugs based on cinnamic acid derivatives.

Optogenetic manipulation of lysosomal physiology and autophagic activity.

Lysosomes are essential degradative organelles and signaling hubs within cells, playing a crucial role in the regulation of macroautophagy/autophagy. Dysfunction of lysosomes and impaired autophagy are closely associated with the development of various neurodegenerative diseases. Enhancing lysosomal activity and boosting autophagy levels holds great promise as effective strategies for treating these diseases. However, there remains a lack of methods to dynamically regulate lysosomal activity and autophagy levels in living cells or animals. In our recent work, we applied optogenetics to manipulate lysosomal physiology and function, developing three lysosome-targeted optogenetic tools: lyso-NpHR3.0, lyso-ArchT, and lyso-ChR2. These new actuators enable light-dependent regulation of key aspects such as lysosomal membrane potential, lumenal pH, hydrolase activity, degradation processes, and Ca2+ dynamics in living cells. Notably, lyso-ChR2 activation induces autophagy via the MTOR pathway while it promotes Aβ clearance through autophagy induction in cellular models of Alzheimer disease. Furthermore, lyso-ChR2 activation reduces Aβ deposition and alleviates Aβ-induced paralysis in Caenorhabditis elegans models of Alzheimer disease. Our lysosomal optogenetic actuators offer a novel method for dynamically regulating lysosomal physiology and autophagic activity in living cells and animals.

Low-dose diazepam improves cognitive function in APP/PS1 mouse models: Involvement of AMPA receptors

Previous studies have indicated a close association between cognitive impairment in patients with neurodegenerative diseases, such as Alzheimer’s disease (AD), and synaptic damage. Diazepam (DZP), a benzodiazepine class drug, is used to control symptoms such as seizures, anxiety, and sleep disorders. These symptoms can potentially manifest throughout the entire course of AD. Therefore, DZP may be utilized in the treatment of AD to manage these symptoms. However, the specific role and mechanisms of DZP in AD remain unclear. In this study, we discovered that long-term administration of a low dose of DZP (0.5 mg/kg) improved cognitive function and protected neurons from damage in APP/PS1 mice. Mechanistic investigations revealed that DZP exerted its neuroprotective effects and reduced Aβ deposition by modulating GluA1 (glutamate AMPA receptor subunit) to influence synaptic function. In conclusion, these findings highlight the potential benefits of DZP as a novel therapeutic approach, suggesting that long-term use of low-dose DZP in early-stage AD patients may be advantageous in slowing disease progression.

Moderation of Amyloid-β Deposition on the Effect of Cholinesterase Inhibitors on Cognition in Mild Cognitive Impairment.

Clinical trial findings on cholinesterase inhibitors (ChEIs) for mild cognitive impairment (MCI) are inconclusive, offering limited support for their MCI treatment. Given that nearly half of amnestic MCI cases lack cerebral amyloid-β (Aβ) deposition, a hallmark of Alzheimer's disease; this Aβ heterogeneity may explain inconsistent results. This study aimed to assess whether Aβ deposition moderates ChEI effects on amnestic MCI cognition. We examined 118 individuals with amnestic MCI (ages 55-90) in a longitudinal cohort study. Baseline and 2-year follow-up assessments included clinical evaluations, neuropsychological testing, and multimodal neuroimaging. Generalized linear models were primarily analyzed to test amyloid positivity's moderation of ChEI effects on cognitive change over 2 years. Cognitive outcomes included Mini-Mental Status Examination score, the total score of the Consortium to Establish a Registry for Alzheimer's Disease neuropsychological battery, and Clinical Dementia Rating-sum of boxes. The analysis found no significant ChEI use x amyloid positivity interaction for all cognitive outcomes. ChEI use, irrespective of Aβ status, was associated with more cognitive decline over the 2-year period. Aβ pathology does not appear to moderate ChEI effects on cognitive decline in MCI.

Amyloid-β deposition in basal frontotemporal cortex is associated with selective disruption of temporal mnemonic discrimination.

Cerebral amyloid-beta (Aβ) accumulation, a hallmark pathology of Alzheimer's disease (AD), precedes clinical impairment by two to three decades. However, it is unclear whether Aβ contributes to subtle memory deficits observed during the preclinical stage. The heterogenous emergence of Aβ deposition may selectively impact certain memory domains, which rely on distinct underlying neural circuits. In this context, we tested whether specific domains of mnemonic discrimination, a neural computation essential for episodic memory, exhibit specific deficits related to early Aβ deposition. We tested 108 cognitively unimpaired human older adults (66% female) who underwent 18F-florbetapir positron emission tomography (Aβ-PET), and a control group of 35 young adults, on a suite of mnemonic discrimination tasks taxing object, spatial, and temporal domains. We hypothesized that Aβ pathology would be selectively associated with temporal discrimination performance due to Aβ's propensity to accumulate in the basal frontotemporal cortex, which supports temporal processing. Consistent with this hypothesis, we found a dissociation in which generalized age-related deficits were found for object and spatial mnemonic discrimination, while Aβ-PET levels were selectively associated with deficits in temporal mnemonic discrimination. Further, we found that higher Aβ-PET levels in medial orbitofrontal and inferior temporal cortex, regions supporting temporal processing, were associated with greater temporal mnemonic discrimination deficits, pointing to the selective vulnerability of circuits related to temporal processing early in AD progression. These results suggest that Aβ accumulation within basal frontotemporal regions may disrupt temporal mnemonic discrimination in preclinical AD, and may serve as a sensitive behavioral biomarker of emerging AD progression.

Chloride intracellular channel 4 blockade improves cognition in mice with Alzheimer's disease: CLIC4 protein expression and tau protein hyperphosphorylation

Numerous academic literature suggests that amyloid-β (Aβ) deposition, tau protein phosphorylation, and irreversible neuronal death are the three major causes of AD. The chloride intracellular channel (CLIC) protein family not only regulates the polarisation of neurons, but also has important implications for neuronal survival. Chloride intracellular channel 4 (CLIC4) can be pathologically activated by cyclin-dependent kinase 5 (Cdk5), which causes a significant increase in the expression of CLIC4 and mediates neuronal apoptosis. CLIC4 knockdown inhibits H2O2-induced neuronal apoptosis; however, the relationship between CLIC4 and AD remains unknown. In the present study, we showed that CLIC4 expression was elevated in the hippocampus of AD mice; knockdown of hippocampal CLIC4 alleviated Aβ25–35-induced cognitive impairment in mice; overexpression of hippocampal CLIC4 accelerated Aβ deposition and tau protein hyperphosphorylation in young AD mice (APP/PS1 mice at three months of age). CLIC4 overexpressing mice had a longer escape latency compared to controls in behavioural testing (Morris water maze and T-maze tests). By Co-immunoprecipitation/mass spectrometry (Co-IP/MS) of HT22 cells to identify proteins that specifically bind to CLIC4, we found interactions with CCAAT enhancer binding protein (C/EBPβ); a critical pathway involved in the development of various neurodegenerative diseases. In addition, the knockdown of hippocampal CLIC4 alleviated AD-like pathology by inhibiting the C/EBPβ/AEP signaling pathway. These data suggest an essential role for high CLIC4 expression in the pathophysiology of AD and reveal that inhibition of CLIC4 expression may provide an opportunity for treatment.

Unveiling the link between glymphatic function and cortical microstructures in post-traumatic stress disorder

PurposeThe discovery of the glymphatic system, crucial for cerebrospinal and interstitial fluid exchange, has enhanced our grasp of brain protein balance and its potential role in neurodegenerative disease prevention and therapy. Detecting early neurodegenerative shifts via noninvasive biomarkers could be key in identifying at-risk individuals for Alzheimer's disease (AD). Our research explores a diffusion tensor imaging (DTI) method that measures cortical mean diffusivity (cMD), potentially a more sensitive indicator of neurodegeneration than traditional macrostructural methods. Materials and methodsWe analyzed 67 post-traumatic stress disorder (PTSD)-diagnosed veterans from the Alzheimer's Disease Neuroimaging Initiative database. Participants underwent structural MRI, DTI, Aβ PET imaging, and cognitive testing. We focused on the DTI-ALPS technique to assess glymphatic function and its relation to cMD, cortical Aβ accumulation, and thickness, accounting for age and APOE ε4 allele variations. ResultsThe cohort, all male with an average age of 68.1 (SD 3.4), showed a strong inverse correlation between DTI-ALPS and cMD in AD-affected regions, especially in the entorhinal, parahippocampal, and fusiform areas. Higher DTI-ALPS readings were consistently linked with greater cortical thickness, independent of Aβ deposits and genetic risk factors. Age and cMD emerged as inversely proportional predictors of DTI-ALPS, indicating a complex interaction with age. ConclusionThe study confirms a meaningful association between glymphatic efficiency and cMD in AD-sensitive zones, accentuating cortical microstructural alterations in PTSD. It positions DTI-ALPS as a viable biomarker for assessing glymphatic function in PTSD, implicating changes in DTI-ALPS as indicative of glymphatic impairment.

Amyloid-β Pathology Is the Common Nominator Proteinopathy of the Primate Brain Aging.

Senile plaques, mainly diffuse, and cerebral amyloid-β (Aβ) angiopathy are prevalent in the aging brain of non-human primates, from lemurs to non-human Hominidae. Aβ but not hyper-phosphorylated tau (HPtau) pathology is the common nominator proteinopathy of non-human primate brain aging. The abundance of Aβ in the aging primate brain is well tolerated, and the impact on cognitive functions is usually limited to particular tasks. In contrast, human brain aging is characterized by the early appearance of HPtau pathology, mainly forming neurofibrillary tangles, dystrophic neurites of neuritic plaques, and neuropil threads, preceding Aβ deposits by several decades and by its severity progressing from selected nuclei of the brain stem, entorhinal cortex, and hippocampus to the limbic system, neocortex, and other brain regions. Neurofibrillary tangles correlate with cognitive impairment and dementia in advanced cases. Aβ pathology is linked in humans to altered membrane protein and lipid composition, particularly involving lipid rafts. Although similar membrane alterations are unknown in non-human primates, membrane senescence is postulated to cause the activated β-amyloidogenic pathway, and Aβ pathology is the prevailing signature of non-human and human primate brain aging.