Biomarkers for Alzheimer’s Disease

Effectiveness of Horticultural Therapy in Older Patients With Dementia: A Meta-Analysis Systemic Review

AIM

Our study aims to assess the effectiveness of horticultural therapy in improving outcomes in older patients with dementia.

DESIGN

A systematic review and meta-analysis.

METHODS

The included studies comprised randomised controlled trials (RCTs) that aimed to assess the effectiveness of horticultural therapy on cognitive function in older patients with dementia. The study design and data extraction were independently conducted by two investigators, who also evaluated the risk of bias using RoB 2.0. The meta-analysis was carried out using Stata 15.1 software.

DATA SOURCES

On November 2023, we searched relevant English and Chinese publications in PubMed, Web of Science, Cochrane Library, Embase, CNKI and Wanfang databases.

RESULTS

The meta-analysis included a total of 9 RCTs, involving 655 older patients diagnosed with dementia. The findings from these studies demonstrated that horticultural therapy had a significant positive impact on various aspects of the patients' well-being when compared to conventional care. Specifically, it was found to improve cognitive function scores, alleviate symptoms of depression, enhance daily activities and enhance overall quality of life. When conducting a subgroup analysis, it was observed that horticultural therapy had a statistically significant effect on cognitive function in older patients with dementia when the intervention frequency was at least two times per week. Furthermore, interventions with a duration of less than 6 months were found to be more effective than those lasting 6 months or longer. Additionally, outdoor horticultural therapy was found to be superior to indoor interventions. Moreover, structured interventions were observed to yield better outcomes compared to non-structured interventions.

CONCLUSION

More high-quality studies are needed to further corroborate these findings due to the low quality of the included studies. Horticultural therapy has been found to have a significantly positive impact on the cognitive function, depression status, ADL, and quality of life of older patients with dementia.

IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE

We provide references for non-pharmacologic treatment of older patients with dementia. WHAT PROBLEM DID THE STUDY ADDRESS?: This study aimed to measure the efficacy of horticultural therapy in older patients with dementia across four dimensions: cognitive function, depression levels, daily living activities and overall quality of life. WHAT WERE THE MAIN FINDINGS?: In older patients with dementia, horticultural therapy has been proven to have a significant positive impact on cognitive function, depressive status, activities of daily living and quality of life. WHERE AND ON WHOM WILL THE RESEARCH HAVE AN IMPACT?: This study will inform non-pharmacological interventions for older patients with dementia worldwide.

PATIENT OR PUBLIC CONTRIBUTION

No Patient or Public Contribution.

Tau proteins and senescent Cells: Targeting aging pathways in Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disease characterized by abnormal accumulation of tau proteins and amyloid-β, leading to neuronal death and cognitive impairment. Recent studies have implicated aging pathways, including dysregulation of tau and cellular senescence in AD pathogenesis. In AD brains, tau protein, which normally stabilizes microtubules, becomes hyperphosphorylated and forms insoluble neurofibrillary tangles. These tau aggregates impair neuronal function and are propagated across the brain's neurocircuitry. Meanwhile, the number of senescent cells accumulating in the aging brain is rising, releasing a pro-inflammatory SASP responsible for neuroinflammation and neurodegeneration. This review explores potential therapeutic interventions for AD targeting tau protein and senescent cells, and tau -directed compounds, senolytics, eliminating senescent cells, and agents that modulate the SASP-senomodulators. Ultimately, a combined approach that incorporates tau-directed medications and targeted senescent cell-based therapies holds promise for reducing the harmful impact of AD's shared aging pathways.

Exploring easily accessible neurophysiological biomarkers for predicting Alzheimer's disease progression: a systematic review

Alzheimer disease (AD) remains a significant global health concern. The progression from preclinical stages to overt dementia has become a crucial point of interest for researchers. This paper reviews the potential of neurophysiological biomarkers in predicting AD progression, based on a systematic literature search following PRISMA guidelines, including 55 studies. EEG-based techniques have been predominantly employed, whereas TMS studies are less common. Among the investigated neurophysiological measures, spectral power measurements and event-related potentials-based measures, including P300 and N200 latencies, have emerged as the most consistent and reliable biomarkers for predicting the likelihood of conversion to AD. In addition, TMS-based indices of cortical excitability and synaptic plasticity have also shown potential in assessing the risk of conversion to AD. However, concerns persist regarding the methodological discrepancies among studies, the accuracy of these neurophysiological measures in comparison to established AD biomarkers, and their immediate clinical applicability. Further research is needed to validate the predictive capabilities of EEG and TMS measures. Advancements in this area could lead to cost-effective, reliable biomarkers, enhancing diagnostic processes and deepening our understanding of AD pathophysiology.

PTBP1 as a potential regulator of disease

Polypyrimidine tract-binding protein 1 (PTBP1) is a member of the heterogeneous nuclear ribonucleoprotein (hnRNP) family, which plays a key role in alternative splicing of precursor mRNA and RNA metabolism. PTBP1 is universally expressed in various tissues and binds to multiple downstream transcripts to interfere with physiological and pathological processes such as the tumor growth, body metabolism, cardiovascular homeostasis, and central nervous system damage, showing great prospects in many fields. The function of PTBP1 involves the regulation and interaction of various upstream molecules, including circular RNAs (circRNAs), microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). These regulatory systems are inseparable from the development and treatment of diseases. Here, we review the latest knowledge regarding the structure and molecular functions of PTBP1 and summarize its functions and mechanisms of PTBP1 in various diseases, including controversial studies. Furthermore, we recommend future studies on PTBP1 and discuss the prospects of targeting PTBP1 in new clinical therapeutic approaches.

Behavioral and Neurological Effects of Edaravone and Noscapine in Albino Wistar Rats

OBJECTIVE

The purpose of the study was to explore Edaravone and Noscapine in anAlCl3-induced Alzheimer's disease (AD) model.

METHODS

Morris Water Maze (MWM), Novel Object Recognition (NOR), andY-maze tests with TNF-α, IL-1, IL-6, amyloid-β, CAT, SOD and MDAlevels were performed, followed by brain histology.

RESULTS

On the probe trial, the MWM demonstrated a decrease in escape latencyfollowed by an increase in the target quadrant. The NOR showeddiscrimination and recognition index scores and Y-maze, revealed arise in spontaneous alterations. TNF-α, IL-1, IL-6, amyloid-β, CATand MDA levels increased, while SOD levels dropped. The results werefound to be significant for combination full and half doses (***p <0.001, **p < 0.01). The treated group's histology ofbrain revealed mild neurodegeneration with hippocampal pyknoticnuclei.

CONCLUSIONS

Thus, Edaravone and Noscapine can be used for thetreatment of AD.    .

Unstable Plaque is a Treatable Cause of Cognitive Decline

While many risk factors are modifiable, there remains a compelling need for novel approaches to prevent cognitive impairment. We propose that unstable carotid plaque causes microemboli that, in turn, cause microinfarcts and other adverse pathophysiological cerebral processes, which individually do not manifest clinically but cumulatively manifest as cognitive decline and ultimately cognitive impairment. Animal models support multiple cerebral microemboli having adverse effects on cognition. By addressing the source for microembolization by endarterectomy or stenting, patients with high-grade atherosclerotic stenosis may have better cognitive outcomes. If our hypothesis is verified, then treatment of carotid plaque at elevated risk of generating cerebral microemboli would be effective in preserving cognition, regardless of whether the stenosis is high-grade or causing cerebral hemispheric hypoperfusion.

Plasma lipidomics in early APP/PS1 female mouse model and its relationship with brain: Is it affected by the estrous cycle?

BACKGROUND

Alzheimer's disease (AD) is the most prevalent dementia, showing higher incidence in women. Besides, lipids play an essential role in brain, and they could be dysregulated in neurodegeneration. Specifically, impaired plasma lipid levels could predict early AD diagnosis. This work aims to identify the main plasma lipids altered in early AD female mouse model and evaluate their relationship with brain lipidome. Also, the possible involvement of the estrous cycle in lipid metabolism has been evaluated.

METHODS

Plasma samples of wild-type (n = 10) and APP/PS1 (n = 10) female mice of 5 months of age were collected, processed, and analysed using a lipidomic mass spectrometry-based method. A statistical analysis involving univariate and multivariate approaches was performed to identify significant lipid differences related to AD between groups. Also, cytology tests were conducted to confirm estrous cycle phases.

RESULTS

Three hundred thirty lipids were detected in plasma, 18 of them showed significant differences between groups; specifically, some triacylglycerols, cholesteryl esters, lysophosphatidylcholines, phosphatidylcholines, and ether-linked phosphatidylcholines, increased in early AD; while other phosphatidylcholines, phosphatidylethanolamines, ceramides, and ether-linked phosphatidylethanolamines decreased in early AD. A multivariate approach was developed from some lipid variables, showing high diagnostic indexes (70% sensitivity, 90% specificity, 80% accuracy). From brain and plasma lipidome, some significant correlations were observed, mainly in the glycerophospholipid family. Also, some differences were found in both plasma and brain lipids, according to the estrous cycle phase.

CONCLUSIONS

Therefore, lipid alterations can be identified in plasma at early AD stages in mice females, with a relationship with brain lipid metabolism for most of the lipid subfamilies, suggesting some lipids as potential AD biomarkers. In addition, the estrous cycle monitoring could be relevant in female studies.

Chlamydia pneumoniae in Alzheimer's disease pathology

While recent advances in diagnostics and therapeutics offer promising new approaches for Alzheimer's disease (AD) diagnosis and treatment, there is still an unmet need for an effective remedy, suggesting new avenues of research are required. Besides many plausible etiologies for AD pathogenesis, mounting evidence supports a possible role for microbial infections. Various microbes have been identified in the postmortem brain tissues of human AD patients. Among bacterial pathogens in AD, Chlamydia pneumoniae (Cp) has been well characterized in human AD brains and is a leading candidate for an infectious involvement. However, no definitive studies have been performed proving or disproving Cp's role as a causative or accelerating agent in AD pathology and cognitive decline. In this review, we discuss recent updates for the role of Cp in human AD brains as well as experimental models of AD. Furthermore, based on the current literature, we have compiled a list of potential mechanistic pathways which may connect Cp with AD pathology.

Brain areas lipidomics in female transgenic mouse model of Alzheimer's disease

Lipids are the major component of the brain with important structural and functional properties. Lipid disruption could play a relevant role in Alzheimer's disease (AD). Some brain lipidomic studies showed significant differences compared to controls, but few studies have focused on different brain areas related to AD. Furthermore, AD is more prevalent in females, but there is a lack of studies focusing on this sex. This work aims to perform a lipidomic study in selected brain areas (cerebellum, amygdala, hippocampus, entire cortex) from wild-type (WT, n = 10) and APPswe/PS1dE9 transgenic (TG, n = 10) female mice of 5 months of age, as a model of early AD, to identify alterations in lipid composition. A lipidomic mass spectrometry-based method was optimized and applied to brain tissue. As result, some lipids showed statistically significant differences between mice groups in cerebellum (n = 68), amygdala (n = 49), hippocampus (n = 48), and the cortex (n = 22). In addition, some lipids (n = 15) from the glycerolipid, phospholipid, and sphingolipid families were statistically significant in several brain areas simultaneously between WT and TG. A selection of lipid variables was made to develop a multivariate approach to assess their discriminant potential, showing high diagnostic indexes, especially in cerebellum and amygdala (sensitivity 70-100%, sensibility 80-100%).

A Comprehensive Review on Potential Molecular Drug Targets for the Management of Alzheimer's Disease

Alzheimer's disease (AD) is an onset and incurable neurodegenerative disorder that has been linked to various genetic, environmental, and lifestyle factors. Recent research has revealed several potential targets for drug development, such as the prevention of Aβ production and removal, prevention of tau hyperphosphorylation, and keeping neurons alive. Drugs that target numerous ADrelated variables have been developed, and early results are encouraging. This review provides a concise map of the different receptor signaling pathways associated with Alzheimer's Disease, as well as insight into drug design based on these pathways. It discusses the molecular mechanisms of AD pathogenesis, such as oxidative stress, aging, Aβ turnover, thiol groups, and mitochondrial activities, and their role in the disease. It also reviews the potential drug targets, in vivo active agents, and docking studies done in AD and provides prospects for future drug development. This review intends to provide more clarity on the molecular processes that occur in Alzheimer's patient's brains, which can be of use in diagnosing and preventing the condition.

Naturally Occurring Cholinesterase Inhibitors from Plants, Fungi, Algae, and Animals: A Review of the Most Effective Inhibitors Reported in 2012-2022

Since the development of the "cholinergic hypothesis" as an important therapeutic approach in the treatment of Alzheimer's disease (AD), the scientific community has made a remarkable effort to discover new and effective molecules with the ability to inhibit the enzyme acetylcholinesterase (AChE). The natural function of this enzyme is to catalyze the hydrolysis of the neurotransmitter acetylcholine in the brain. Thus, its inhibition increases the levels of this neurochemical and improves the cholinergic functions in patients with AD alleviating the symptoms of this neurological disorder. In recent years, attention has also been focused on the role of another enzyme, butyrylcholinesterase (BChE), mainly in the advanced stages of AD, transforming this enzyme into another target of interest in the search for new anticholinesterase agents. Over the past decades, Nature has proven to be a rich source of bioactive compounds relevant to the discovery of new molecules with potential applications in AD therapy. Bioprospecting of new cholinesterase inhibitors among natural products has led to the discovery of an important number of new AChE and BChE inhibitors that became potential lead compounds for the development of anti-AD drugs. This review summarizes a total of 260 active compounds from 142 studies which correspond to the most relevant (IC50 ≤ 15 μM) research work published during 2012-2022 on plant-derived anticholinesterase compounds, as well as several potent inhibitors obtained from other sources like fungi, algae, and animals.

Presence of Preoperative Neurodegeneration Biofluid Markers in Patients with Postoperative Delirium

BACKGROUND

The pathophysiology of delirium is incompletely understood, including what molecular pathways are involved in brain vulnerability to delirium. This study examined whether preoperative plasma neurodegeneration markers were elevated in patients who subsequently developed postoperative delirium through a retrospective case-control study.

METHODS

Inclusion criteria were patients of 65 yr of age or older, undergoing elective noncardiac surgery with a hospital stay of 2 days or more. Concentrations of preoperative plasma P-Tau181, neurofilament light chain, amyloid β1-42 (Aβ42), and glial fibrillary acidic protein were measured with a digital immunoassay platform. The primary outcome was postoperative delirium measured by the Confusion Assessment Method. The study included propensity score matching by age and sex with nearest neighbor, such that each patient in the delirium group was matched by age and sex with a patient in the no-delirium group.

RESULTS

The initial cohort consists of 189 patients with no delirium and 102 patients who developed postoperative delirium. Of 291 patients aged 72.5 ± 5.8 yr, 50.5% were women, and 102 (35%) developed postoperative delirium. The final cohort in the analysis consisted of a no-delirium group (n = 102) and a delirium group (n = 102) matched by age and sex using the propensity score method. Of the four biomarkers assayed, the median value for neurofilament light chain was 32.05 pg/ml for the delirium group versus 23.7 pg/ml in the no-delirium group. The distribution of biomarker values significantly differed between the delirium and no-delirium groups (P = 0.02 by the Kolmogorov-Smirnov test) with the largest cumulative probability difference appearing at the biomarker value of 32.05 pg/ml.

CONCLUSIONS

These results suggest that patients who subsequently developed delirium are more likely to be experiencing clinically silent neurodegenerative changes before surgery, reflected by changes in plasma neurofilament light chain biomarker concentrations, which may identify individuals with a preoperative vulnerability to subsequent cognitive decline.

EDITOR’S PERSPECTIVE

Correlation of serum complement factor 5a level with inflammatory response and cognitive function in patients with Alzheimer's disease of different severity

BACKGROUND

Alzheimer's disease (AD) is a common cause of dementia. Serum complement factor 5a (C5a) is exceedingly implicated in AD. We explored the role of C5a levels in AD patients of different severity.

METHODS

Mild, moderate, and severe AD patients, and healthy controls were included. C5a and pro-inflammatory factor (TNF-α, IL-1β, IL-6, CRP) levels were assessed by ELISA, and cognitive function was evaluated by Mini-Mental state examination (MMSE) score. The correlations between C5a, inflammatory factor levels, MMSE score, and plasma Aβ42/Aβ40 ratio were analyzed by Pearson tests. Independent risk factors for AD aggravation were assessed by logistic multivariate regression analysis. According to the cut-off value of receiver operating characteristic (ROC) curve analysis of C5a level, AD patients were assigned into low/high expression groups, and severe AD incidence was compared. Severe AD cumulative incidence was analyzed by Kaplan-Meier curve.

RESULTS

Serum C5a, TNF-α, IL-1β, IL-6 and CRP levels were raised, and MMSE score was lowered in AD. Serum C5a, TNF-α, IL-1β, IL-6 and CRP levels in severe AD patients were higher than those in mild/moderate AD patients, but there were no significant differences in these cytokines between moderate and mild AD groups. The MMSE score of severe AD patients was lower than that of mild/moderate AD patients. Serum C5a level was positively correlated with serum TNF-α, IL-1β, IL-6, and CRP levels, and negatively correlated with MMSE score, with no obvious correlation with plasma Aβ42/Aβ40 ratio. Serum C5a level was one of the independent risk factors for AD aggravation. The occurrence of severe AD might be related to an increase in serum C5a level.

CONCLUSION

Serum C5a level increased with AD severity, and its expression was positively correlated with serum pro-inflammatory factor levels, and negatively correlated with cognitive function.

Effects of adverse childhood health experiences on cognitive function in Chinese middle-aged and older adults: mediating role of depression

BACKGROUND

Adverse childhood experiences are critical factors in depression and cognitive decrease, but the effect of adverse childhood health experiences (ACHEs) on cognitive function and the role of depression have not been fully studied.

METHODS

Data were taken from the China Health and Retirement Longitudinal Study (CHARLS) of 2014 and 2018. This study used indicators of situational memory ability and mental status to measure cognitive capacity. Besides analyzing the different types of ACHEs, scores for ACHEs were calculated to represent the severity of ACHEs. The Center for Epidemiologic Studies Depression Scale (CES-D) was used to assess depression. The analysis of this study employed two different analytical strategies in order to examine the mediated effects of depression. We used Sobel's test and Baron and Kenny's causal step approach, which utilized a generalized least squares regression model. Furthermore, a logistic regression model was used to evaluate the robustness of the Karlson-Holm-Breen (KHB) approach.

RESULTS

In this study, 6301 individuals who met the requirements of the study were included. We found that being confined to bed (ACHE3) (β=-0.3846, p = 0.022) in childhood had a negative impact on cognitive function. Similarly, ACHEs had a negative effect on cognitive function (β=-0.0819, p = 0.090). And after the depression had been introduced into the model, the regression coefficient of ACHEs on cognitive function was no longer significant (β=-0.0170, p = 0.727). The Sobel test showed that for ACHE3, the mediated proportion of the total effect of depression was 36.92%. While for ACHEs, the proportion of the mediated effect of depression was 70.11%. Finally, a robustness test of the mediating effect using the KHB method revealed that the mediating effect still existed. Further, based on different gender, age, and educational levels, the heterogeneity test indicated that the relationship between ACHEs and cognitive function and mediating effects of the depression were different as well as passing the robustness test of the interaction.

CONCLUSION

The decline in cognition had been shown to be correlated with ACHEs and depression mediated this relationship. Positive interventions might help to improve cognitive performance in individuals suffering from ACHEs and depression.

GFAP as a Potential Biomarker for Alzheimer's Disease: A Systematic Review and Meta-Analysis

Blood biomarkers have been considered tools for the diagnosis, prognosis, and monitoring of Alzheimer's disease (AD). Although amyloid-β peptide (Aβ) and tau are primarily blood biomarkers, recent studies have identified other reliable candidates that can serve as measurable indicators of pathological conditions. One such candidate is the glial fibrillary acidic protein (GFAP), an astrocytic cytoskeletal protein that can be detected in blood samples. Increasing evidence suggests that blood GFAP levels can be used to detect early-stage AD. In this systematic review and meta-analysis, we aimed to evaluate GFAP in peripheral blood as a biomarker for AD and provide an overview of the evidence regarding its utility. Our analysis revealed that the GFAP level in the blood was higher in the Aβ-positive group than in the negative groups, and in individuals with AD or mild cognitive impairment (MCI) compared to the healthy controls. Therefore, we believe that the clinical use of blood GFAP measurements has the potential to accelerate the diagnosis and improve the prognosis of AD.

Exercise suppresses neuroinflammation for alleviating Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease, with the characteristics of neurofibrillary tangle (NFT) and senile plaque (SP) formation. Although great progresses have been made in clinical trials based on relevant hypotheses, these studies are also accompanied by the emergence of toxic and side effects, and it is an urgent task to explore the underlying mechanisms for the benefits to prevent and treat AD. Herein, based on animal experiments and a few clinical trials, neuroinflammation in AD is characterized by long-term activation of pro-inflammatory microglia and the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasomes. Damaged signals from the periphery and within the brain continuously activate microglia, thus resulting in a constant source of inflammatory responses. The long-term chronic inflammatory response also exacerbates endoplasmic reticulum oxidative stress in microglia, which triggers microglia-dependent immune responses, ultimately leading to the occurrence and deterioration of AD. In this review, we systematically summarized and sorted out that exercise ameliorates AD by directly and indirectly regulating immune response of the central nervous system and promoting hippocampal neurogenesis to provide a new direction for exploring the neuroinflammation activity in AD.

Advances in sample preparation and HPLC-MS/MS methods for determining amyloid-β peptide in biological samples: a review

Alzheimer's disease (AD), a neurological disorder, is a major public health concern and the most common form of dementia. Its typical symptoms include memory loss, confusion, changes in personality, and cognitive impairment, which result in patients gradually losing independence. Over the last decades, some studies have focused on searching for effective biomarkers as early diagnostic indicators of AD. Amyloid-β (Aβ) peptides have been consolidated as reliable AD biomarkers and have been incorporated into modern diagnostic research criteria. However, quantitative analysis of Aβ peptides in biological samples remains a challenge because both the sample and the physical-chemical properties of these peptides are complex. During clinical routine, Aβ peptides are measured in the cerebrospinal fluid by immunoassays, but the availability of a specific antibody is critical-in some cases, an antibody may not exist, or its specificity may be inadequate, leading to low sensitivity and false results. HPLC-MS/MS has been reported as a sensitive and selective method for determining different fragments of Aβ peptides in biological samples simultaneously. Developments in sample preparation techniques (preconcentration platforms) such as immunoprecipitation, 96-well plate SPME, online SPME, and fiber-in-tube SPME have enabled not only effective enrichment of Aβ peptides present at trace levels in biological samples, but also efficient exclusion of interferents from the sample matrix (sample cleanup). This high extraction efficiency has provided MS platforms with higher sensitivity. Recently, methods affording LLOQ values as low as 5 pg mL^-1 have been reported. Such low LLOQ values are adequate for quantifying Aβ peptides in complex matrixes including cerebrospinal fluid (CSF) and plasma samples. This review summarizes the advances in mass spectrometry (MS)-based methods for quantifying Aβ peptides and covers the period 1992-2022. Important considerations regarding the development of the HPLC-MS/MS method such as the sample preparation step, optimization of the HPLC-MS/MS parameters, and matrix effects are described. Clinical applications, difficulties related to analysis of plasma samples, and future trends of these MS/MS-based methods are also discussed.

Status of Metabolomic Measurement for Insights in Alzheimer's Disease Progression-What Is Missing?

Alzheimer's disease (AD) is an aging-related neurodegenerative disease, leading to the progressive loss of memory and other cognitive functions. As there is still no cure for AD, the growth in the number of susceptible individuals represents a major emerging threat to public health. Currently, the pathogenesis and etiology of AD remain poorly understood, while no efficient treatments are available to slow down the degenerative effects of AD. Metabolomics allows the study of biochemical alterations in pathological processes which may be involved in AD progression and to discover new therapeutic targets. In this review, we summarized and analyzed the results from studies on metabolomics analysis performed in biological samples of AD subjects and AD animal models. Then this information was analyzed by using MetaboAnalyst to find the disturbed pathways among different sample types in human and animal models at different disease stages. We discuss the underlying biochemical mechanisms involved, and the extent to which they could impact the specific hallmarks of AD. Then we identify gaps and challenges and provide recommendations for future metabolomics approaches to better understand AD pathogenesis.

CDiP technology for reverse engineering of sporadic Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease that causes cognitive impairment for which neither treatable nor preventable approaches have been confirmed. Although genetic factors are considered to contribute to sporadic AD, for the majority of AD patients, the exact causes of AD aren't fully understood. For AD genetics, we developed cellular dissection of polygenicity (CDiP) technology to identify the smallest unit of AD, i.e., genetic factors at a cellular level. By CDiP, we found potential therapeutic targets, a rare variant for disease stratification, and polygenes to predict real-world AD by using the real-world data of AD cohort studies (Alzheimer's Disease Neuroimaging Initiative: ADNI and Japanese Alzheimer's Disease Neuroimaging Initiative: J-ADNI). In this review, we describe the components and results of CDiP in AD, induced pluripotent stem cell (iPSC) cohort, a cell genome-wide association study (cell GWAS), and machine learning. And finally, we discuss the future perspectives of CDiP technology for reverse engineering of sporadic AD toward AD eradication.

Direct coupling of fiber-in-tube solid-phase microextraction with tandem mass spectrometry to determine amyloid beta peptides as biomarkers for Alzheimer's disease in cerebrospinal fluid samples

Current research efforts at neurological diseases have focused on identifying novel biomarkers to aid in diagnosis, to provide accurate prognostic information, and to monitor disease progression. This study presents the direct coupling of fiber-in-tube solid-phase microextraction to tandem mass spectrometry as a reliable method to determine amyloid beta peptides (Aβ38, Aβ40, and Aβ42) as biomarkers for Alzheimer's disease in cerebrospinal fluid (CSF) samples. To obtain the biocompatible fiber-in-tube SPME capillary, a PEEK tube segment was longitudinally packed with fine fibers [nitinol wires coated with a zwitterionic polymeric ionic liquid], to act as selective extraction medium. The fiber-in-tube SPME-MS/MS method integrated analyte extraction/enrichment and sample cleanup (exclusion of interferents) into one step. The method provided lower limits of quantification (LLOQ: 0.2 ng mL^-1 for Aβ38 and 0.1 ng mL^-1 for Aβ40 and Aβ42), high precision (CV lower than 11.6%), and high accuracy (relative standard deviation lower than 15.1%). This method was successfully applied to determine Aβ peptides in CSF samples obtained from AD patients (n = 8) and controls (healthy volunteers, n = 10). Results showed that Aβ42 levels in the CSF samples obtained from AD patients were significantly lower compared to healthy controls (p < 0.05). On the basis of the ROC analysis results, the Aβ42/Aβ40 ratio (AUC = 0.950, p < 0.01; 95%) performed significantly better than Aβ42 alone (AUC = 0.913, p < 0.01; 95%) in discriminating between AD patients and healthy controls and presented better diagnostic ability for AD. The novelties of this study are not only related to evaluating Aβ peptides as AD biomarkers, but also to demonstrating direct online coupling of fiber-in-tube SPME with MS/MS as a quantitative high-throughput method for bioanalysis.

Identification of hub proteins in cerebrospinal fluid as potential biomarkers of Alzheimer's disease by integrated bioinformatics

BACKGROUND

Alzheimer's disease (AD) is a heterogeneous neurodegenerative disease with complex pathophysiology. Therefore, the identification of novel effective fluid biomarkers is essential for Alzheimer's disease diagnosis and drug development. This study aimed to identify potential candidate hub proteins in cerebrospinal fluid for precise Alzheimer's disease diagnosis using bioinformatics methods.

METHODS

A total of 29 co-significant differentially expressed proteins were identified by differential protein expression analysis in four different cohorts. Functional enrichment analysis revealed that most of these proteins were enriched in pathways related to glycometabolism. Using the Least Absolute Shrinkage and Selection Operator (LASSO) and random forest feature selection methods, six hub proteins [14-3-3 protein zeta/delta (YWHAZ), SPARC-related modular calcium-binding protein 1 (SMOC1), aldolase A (ALDOA), pyruvate kinase isoenzyme type M2 (PKM), chitinase-3-like protein 1 (CHI3L1), and secreted phosphoprotein 1 (SPP1)] were identified.

RESULTS

These six hub proteins were upregulated in the cerebrospinal fluid of patients with Alzheimer's disease compared with cognitively unimpaired control individuals. Meanwhile, SMOC1, ALDOA, and PKM were specifically upregulated in the cerebrospinal fluid of patients with Alzheimer's disease but not in other neurodegenerative diseases. Build AD diagnostic models showed that a single hub protein or six hub proteins combination had an excellent ability to discriminate Alzheimer's disease.

CONCLUSIONS

In conclusion, our study suggests that these identified hub proteins, which are related to glycometabolism, may be potential biomarkers for further basic and clinical research in Alzheimer's disease.

Beta-Amyloid Peptide in Tears: An Early Diagnostic Marker of Alzheimer's Disease Correlated with Choroidal Thickness

We aimed to evaluate the diagnostic role of Alzheimer's disease (AD) biomarkers in tears as well as their association with retinal and choroidal microstructures. In a cross-sectional study, 35 subjects (age 71.7 ± 6.9 years) were included: 11 with prodromal AD (MCI), 10 with mild-to-moderate AD, and 14 healthy controls. The diagnosis of AD and MCI was confirmed according to a complete neuropsychological evaluation and PET or MRI imaging. After tear sample collection, β-amyloid peptide Aβ1-42 concentration was analyzed using ELISA, whereas C-terminal fragments of the amyloid precursor protein (APP-CTF) and phosphorylated tau (p-tau) were assessed by Western blot. Retinal layers and choroidal thickness (CT) were acquired by spectral-domain optical coherence tomography (SD-OCT). Aβ1-42 levels in tears were able to detect both MCI and AD patients with a specificity of 93% and a sensitivity of 81% (AUC = 0.91). Tear levels of Aβ1-42 were lower, both in the MCI (p < 0.01) and in the AD group (p < 0.001) when compared to healthy controls. Further, Aβ1-42 was correlated with psychometric scores (p < 0.001) and CT (p < 0.01). CT was thinner in the affected patients (p = 0.035). No differences were observed for APP-CTF and p-tau relative abundance in tears. Testing Aβ1-42 levels in tears seems to be a minimally invasive, cost-saving method for early detection and diagnosis of AD.

Toward Prevention and Reduction of Alzheimer's Disease

Different investigations lead to the urgent need to generate validated clinical protocols as a tool for medical doctors to orientate patients under risk for a preventive approach to control Alzheimer's disease. Moreover, there is consensus that the combined effects of risk factors for the disease can be modified according to lifestyle, thus controlling at least 40% of cases. The other fraction of cases are derived from candidate genes and epigenetic components as a relevant factor in AD pathogenesis. At this point, it appears to be of critical relevance the search for molecular biomarkers that may provide information on probable pathological events and alert about early detectable risks to prevent symptomatic events of the disease. These precocious detection markers will then allow early interventions of non-symptomatic subjects at risk. Here, we summarize the status and potential avenues of prevention and highlight the usefulness of biological and reliable markers for AD.

Chiral Amino Acid Profiling in Serum Reveals Potential Biomarkers for Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is a complex neurodegenerative disease, and increasing evidence has linked dysregulation of amino acids to AD pathogenesis. However, the existing studies often ignore the chirality of amino acids, and some results are inconsistent and controversial. The changes of amino acid profiles in AD from the perspective of enantiomers remain elusive.

OBJECTIVE

The purpose of this study is to investigate whether the levels of amino acids, especially D-amino acids, are deregulated in the peripheral serum of AD patients, with the ultimate goal of discovering novel biomarkers for AD.

METHODS

The chiral amino acid profiles were determined by HPLC-MS/MS with a pre-column derivatization method. Experimental data obtained from 37 AD patients and 34 healthy controls (HC) were statistically analyzed.

RESULTS

Among the 35 amino acids detected, D-proline, D/total-proline ratio, D-aspartate, and D/total-aspartate ratio were decreased, while D-phenylalanine was elevated in AD compared to HC. Significant age-dependent increases in D-proline, D/total-proline ratio, and D-phenylalanine were observed in HC, but not in AD. Receiver operator characteristic analyses of the combination of D-proline, D-aspartate, D-phenylalanine, and age for discriminating AD from HC provided satisfactory area under the curve (0.87), specificity (97.0%), and sensitivity (83.8%). Furthermore, the D-aspartate level was significantly decreased with the progression of AD, as assessed by the Clinical Dementia Rating Scale and Mini-Mental State Examination.

CONCLUSION

The panels of D-proline, D-phenylalanine, and D-aspartate in peripheral serum may serve as novel biomarker candidates for AD. The latter parameter is further associated with the severity of AD.

Utility of Amyloid Positron Emission Tomography Imaging in Older Adults With Epilepsy and Cognitive Decline

In older adults with cognitive decline and epilepsy, diagnosing the etiology of cognitive decline is challenging. We identified 6 subjects enrolled in the Imaging Dementia-Evidence of Amyloid Imaging Scanning (IDEAS) study and nonlesional epilepsy. Three cognitive neurologists reviewed each case to determine the likelihood of underlying Alzheimer's disease (AD) pathology. Their impressions were compared to amyloid PET findings. In 3 cases the impression was concordant with PET findings. In 2 cases "possibly suggestive," the PET reduced diagnostic uncertainty, with 1 having a PET without elevated amyloid and the other PET with intermediate amyloid. In the remaining case with lack of reviewer concordance, the significance of PET with elevated amyloid remains uncertain. This case series highlights that in individuals with a history of epilepsy and cognitive decline, amyloid PET can be a useful tool in evaluating the etiology of cognitive decline when used in an appropriate context.

The 677C > T variant in methylenetetrahydrofolate reductase causes morphological and functional cerebrovascular deficits in mice

Vascular contributions to cognitive impairment and dementia (VCID) particularly Alzheimer's disease and related dementias (ADRDs) are increasing; however, mechanisms driving cerebrovascular decline are poorly understood. Methylenetetrahydrofolate reductase (MTHFR) is a critical enzyme in the folate and methionine cycles. Variants in MTHFR, notably 677 C > T, are associated with dementias, but no mouse model existed to identify mechanisms by which MTHFR677C > T increases risk. Therefore, MODEL-AD created a novel knock-in (KI) strain carrying the Mthfr677C > T allele on the C57BL/6J background (Mthfr677C > T) to characterize morphology and function perturbed by the variant. Consistent with human clinical data, Mthfr677C > T mice have reduced enzyme activity in the liver and elevated plasma homocysteine levels. MTHFR enzyme activity is also reduced in the Mthfr677C > T brain. Mice showed reduced tissue perfusion in numerous brain regions by PET/CT as well as significantly reduced vascular density, pericyte number and increased GFAP-expressing astrocytes in frontal cortex. Electron microscopy revealed cerebrovascular damage including endothelial and pericyte apoptosis, reduced luminal size, and increased astrocyte and microglial presence in the microenvironment. Collectively, these data support a mechanism by which variations in MTHFR perturb cerebrovascular health laying the foundation to incorporate our new Mthfr677C > T mouse model in studies examining genetic susceptibility for cerebrovascular dysfunction in ADRDs.

Suicide-Related Single Nucleotide Polymorphisms, rs4918918 and rs10903034: Association with Dementia in Older Adults

Dementia has enormous implications for patients and the health care system. Genetic markers are promising for detecting the risk of cognitive impairment. We hypothesized that genetic variants associated with suicide risk might significantly increase the risk of cognitive decline because suicide in older adults is often a consequence of cognitive impairment. We investigated several single-nucleotide polymorphisms that were initially associated with suicide risk in dementia older adults and identified the APOE gene alleles. The study was performed with subjects over the age of 65: 112 patients with dementia and 146 healthy volunteers. The MMSE score was used to assess cognitive functions. Study participants were genotyped using real-time PCR (APOE: rs429358, rs7412; genes associated with suicide: rs9475195, rs7982251, rs2834789, rs358592, rs4918918, rs3781878, rs10903034, rs165774, rs16841143, rs11833579 rs10898553, rs7296262, rs3806263, and rs2462021). Genotype analysis revealed the significance of APOEε4, APOEε2, and rs4918918 (SORBS1) when comparing dementia and healthy control groups. The association of APOEε4, APOEε2, and rs10903034 (IFNLR1) with the overall MMSE score was indicated. The study found an association with dementia of rs4918918 (SORBS1) and rs10903034 (IFNLR1) previously associated with suicide and confirmed the association of APOEε4 and APOEε2 with dementia.

Treadmill exercise promotes E3 ubiquitin ligase to remove amyloid β and P-tau and improve cognitive ability in APP/PS1 transgenic mice

Background

Moderate physical exercise is conducive to the brains of healthy humans and AD patients. Previous reports have suggested that treadmill exercise plays an anti-AD role and improves cognitive ability by promoting amyloid clearance, inhibiting neuronal apoptosis, reducing oxidative stress level, alleviating brain inflammation, and promoting autophagy–lysosome pathway in AD mice. However, few studies have explored the relationships between the ubiquitin–proteasome system and proper exercise in AD. The current study was intended to investigate the mechanism by which the exercise-regulated E3 ubiquitin ligase improves AD.

Methods

Both wild type and APP/PS1 transgenic mice were divided into sedentary (WTC and ADC) and exercise (WTE and ADE) groups (n = 12 for each group). WTE and ADE mice were subjected to treadmill exercise of 12 weeks in order to assess the effect of treadmill running on learning and memory ability, Aβ plaque burden, hyperphosphorylated Tau protein and E3 ubiquitin ligase.

Results

The results indicated that exercise restored learning and memory ability, reduced Aβ plaque areas, inhibited the hyperphosphorylation of Tau protein activated PI3K/Akt/Hsp70 signaling pathway, and improved the function of the ubiquitin–proteasome system (increased UCHL-1 and CHIP levels, decreased BACE1 levels) in APP/PS1 transgenic mice.

Conclusions

These findings suggest that exercise may promote the E3 ubiquitin ligase to clear β-amyloid and hyperphosphorylated Tau by activating the PI3K/Akt signaling pathway in the hippocampus of AD mice, which is efficient in ameliorating pathological phenotypes and improving learning and memory ability.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02607-7.

Diagnostic accuracy of multi-component spatial-temporal gait parameters in older adults with amnestic mild cognitive impairment

Objective

This study aimed to develop a diagnostic model of multi-kinematic parameters for patients with amnestic mild cognitive impairment (aMCI).

Method

In this cross-sectional study, 94 older adults were included (33 cognitively normal, CN; and 61 aMCI). We conducted neuropsychological battery tests, such as global cognition and cognitive domains, and collected gait parameters by an inertial-sensor gait analysis system. Multivariable regression models were used to identify the potential diagnostic variables for aMCI. Receiver operating characteristic (ROC) curves were applied to assess the diagnostic accuracy of kinematic parameters in discriminating aMCI from healthy subjects.

Results

Multivariable regression showed that multi-kinematic parameters were the potential diagnostic variables for aMCI. The multi-kinematic parameter model, developed using Timed Up and Go (TUG) time, stride length, toe-off/heel stride angles, one-leg standing (OLS) time, and braking force, showed areas under ROC (AUC), 0.96 [95% confidence interval (CI), 0.905–0.857]; sensitivity, 0.90; and specificity, 0.91. In contrast, a single kinematic parameter’s sensitivity was 0.26–0.95 and specificity was 0.21–0.90. Notably, the separating capacity of multi-kinematic parameters was highly similar to Montreal Cognitive Assessment (MoCA; AUC: 0.96 vs. 0.95). Compared to cognitive domain tests, the separating ability was comparable to Auditory Verbal Learning Test (AVLT) and Boston Naming Test (BNT; AUC: 0.96 vs. 0.97; AUC: 0.96 vs. 0.94).

Conclusion

We developed one diagnostic model of multi-kinematic parameters for patients with aMCI in Foshan.

Improving Our Understanding of Driving Changes in Preclinical and Early Symptomatic Alzheimer’s Disease: The Role of Naturalistic Driving Studies

Research on how preclinical and early symptomatic Alzheimer’s disease (AD) impacts driving behavior is in its infancy, with several important research areas yet to be explored. This paper identifies research gaps and suggests priorities for driving studies over the next few years among those at the earliest stages of AD. These priorities include how individual differences in demographic and biomarker measures of AD pathology, as well as differences in the in-vehicle and external driving environment, affect driving behavior. Understanding these differences is important to developing future interventions to increase driving safety among those at the earliest stages of AD.

A Novel Automatic Quantification Protocol for Biomarkers of Tauopathies in the Hippocampus and Entorhinal Cortex of Post-Mortem Samples Using an Extended Semi-Siamese U-Net

Simple Summary

Tauopathies is a term coined to describe an umbrella of disorders characterized by abnormal Tau polypeptide deposits in neurons, glial cells, and extracellular space. In this work, we propose a novel quantification protocol for the study of tauopathies based on the U-Net neural network architecture. We also compare the proposed method against other state of the art variations of the U-Net to test its efficacy.

Abstract

Efforts have been made to diagnose and predict the course of different neurodegenerative diseases through various imaging techniques. Particularly tauopathies, where the tau polypeptide is a key participant in molecular pathogenesis, have significantly increased their morbidity and mortality in the human population over the years. However, the standard approach to exploring the phenomenon of neurodegeneration in tauopathies has not been directed at understanding the molecular mechanism that causes the aberrant polymeric and fibrillar behavior of the tau protein, which forms neurofibrillary tangles that replace neuronal populations in the hippocampal and cortical regions. The main objective of this work is to implement a novel quantification protocol for different biomarkers based on pathological post-translational modifications undergone by tau in the brains of patients with tauopathies. The quantification protocol consists of an adaptation of the U-Net neural network architecture. We used the resulting segmentation masks for the quantification of combined fluorescent signals of the different molecular changes tau underwent in neurofibrillary tangles. The quantification considers the neurofibrillary tangles as an individual study structure separated from the rest of the quadrant present in the images. This allows us to detect unconventional interaction signals between the different biomarkers. Our algorithm provides information that will be fundamental to understanding the pathogenesis of dementias with another computational analysis approach in subsequent studies.

Alzheimer's disease: a scoping review of biomarker research and development for effective disease diagnosis

INTRODUCTION

Alzheimer's disease (AD) is regarded as the foremost reason for neurodegeneration that prominently affects the geriatric population. Characterized by extracellular accumulation of amyloid-beta (Aβ), intracellular aggregation of hyperphosphorylated tau (p-tau), and neuronal degeneration that causes impairment of memory and cognition. Amyloid/tau/neurodegeneration (ATN) classification is utilized for research purposes and involves amyloid, tau, and neuronal injury staging through MRI, PET scanning, and CSF protein concentration estimations. CSF sampling is invasive, and MRI and PET scanning requires sophisticated radiological facilities which limit its widespread diagnostic use. ATN classification lacks effectiveness in preclinical AD.

AREAS COVERED

This publication intends to collate and review the existing biomarker profile and the current research and development of a new arsenal of biomarkers for AD pathology from different biological samples, microRNA (miRNA), proteomics, metabolomics, artificial intelligence, and machine learning for AD screening, diagnosis, prognosis, and monitoring of AD treatments.

EXPERT OPINION

It is an accepted observation that AD-related pathological changes occur over a long period of time before the first symptoms are observed providing ample opportunity for detection of biological alterations in various biological samples that can aid in early diagnosis and modify treatment outcomes.

Contributive Role of Hyperglycemia and Hypoglycemia Towards the Development of Alzheimer's Disease

Alzheimer's disease (AD) is one of the causes of dementia that results from several infections/biological conditions leading to either cell disruption or loss of neuronal communication. Studies have documented the accumulation of two proteins, beta-amyloid (Aβ), which accumulates on the exteriors of neurons, and tau (Tau), which assembles at the interiors of brain cells and is chiefly liable for the progression of the disease. Several molecular and cellular pathways account for the accumulation of amyloid-β and the formation of neurofibrillary tangles, which are phosphorylated variants of Tau protein. Moreover, research has revealed a potential connection between AD and diabetes. It has also been demonstrated that both hypoglycemia and hyperglycemia have a significant role in the development of AD. In addition, SUMO (small ubiquitin-like modifier protein) plays a crucial role in the pathogenesis of AD. SUMOylation is the process by which modification of amyloid precursor protein (APP) and Tau takes place. Furthermore, Drosophila melanogaster has proven to be an efficient model organism in studies to establish the relationship between AD and variations in blood glucose levels. In addition, the review successfully identifies the common pathway that links the effects of fluctuations in glucose levels on AD pathogenesis and advancements.

Glucose metabolism and AD: evidence for a potential diabetes type 3

BACKGROUND

Alzheimer's disease is the most prevalent cause of dementia in the elderly. Neuronal death and synaptic dysfunctions are considered the main hallmarks of this disease. The latter could be directly associated to an impaired metabolism. In particular, glucose metabolism impairment has demonstrated to be a key regulatory element in the onset and progression of AD, which is why nowadays AD is considered the type 3 diabetes.

METHODS

We provide a thread regarding the influence of glucose metabolism in AD from three different perspectives: (i) as a regulator of the energy source, (ii) through several metabolic alterations, such as insulin resistance, that modify peripheral signaling pathways that influence activation of the immune system (e.g., insulin resistance, diabetes, etc.), and (iii) as modulators of various key post-translational modifications for protein aggregation, for example, influence on tau hyperphosphorylation and other important modifications, which determine its self-aggregating behavior and hence Alzheimer's pathogenesis.

CONCLUSIONS

In this revision, we observed a 3 edge-action in which glucose metabolism impairment is acting in the progression of AD: as blockade of energy source (e.g., mitochondrial dysfunction), through metabolic dysregulation and post-translational modifications in key proteins, such as tau. Therefore, the latter would sustain the current hypothesis that AD is, in fact, the novel diabetes type 3.

Assessment of Lipid Peroxidation in Alzheimer's Disease Differential Diagnosis and Prognosis

Alzheimer’s disease (AD) and other dementias are becoming increasingly common in the older population, and the number of people affected is expected to increase in a few years. Nowadays, biomarkers used in early AD diagnosis are expensive and invasive. Therefore, this research field is growing. In fact, peroxidation by-products derived from the oxidation of brain lipids (arachidonic (AA), docosahexanoic (DHA) and adrenic acid (AdA)) could be potential biomarkers, participating in the mechanisms of inflammation, neurotoxicity and cell death in AD pathology. Previous studies have shown specificity between lipid peroxidation compounds and other dementias (e.g., Lewy bodies (DLB), frontotemporal dementia (FTD)), but more research is required. Lipid peroxidation compounds (prostaglandins, isoprostanes, isofurans, neuroprostanes, neurofurans, dihomo-isoprostanes and dihomo-isofurans) were analysed by liquid chromatography and mass spectrometry in plasma samples from participants classified into a healthy group (n = 80), a mild cognitive impairment due to AD group (n = 106), a mild dementia due to AD group (n = 70), an advanced dementia due to AD group (n = 11) and a group of other non-AD dementias (n = 20). Most of these compounds showed statistically significant differences between groups (p < 0.05), showing higher levels for the healthy and non-AD groups than the AD groups. Then, a multivariate analysis was carried out on these compounds, showing good diagnosis indexes (AUC 0.77, sensitivity 81.3%, positive predictive value 81%). Moreover, evaluating AD disease prognosis, two compounds (15-F2t-IsoP and 14(RS)-14-F4t-NeuroP) and three total parameters (isoprostanes, isofurans and neurofurans) showed significant differences among groups. Some compounds derived from the oxidation of AA, DHA and AdA have demonstrated their potential use in differential AD diagnosis. Specifically, 15-F2t-IsoP, 14(RS)-14-F4t-NeuroP and the total parameters for isoprostanes, isofurans and neurofurans have shown prognostic value for AD from its earliest stages to its most severe form.

Novel Nutraceutical Compounds in Alzheimer Prevention

Alzheimer's disease (AD) incidence is increasing worldwide at an alarming rate. Considering this increase, prevention efforts, stemming from scientific research, health education, and public policies, are critical. Clinical studies evidenced that healthy lifestyles along with natural multitarget and disease-modifying agents have a preventative impact on AD or mitigate symptoms in diagnosed patients. The pathological alterations of AD start 30 years before symptoms, and it is essential to develop the capacity to detect those changes. In this regard, molecular biomarkers that detect early pathological manifestations are helpful. Based on markers data, early preventive interventions could reduce more than 40% of AD cases. Protective actions include exercise, shown to induce neurogenesis, cognitive stimulation, intellectual-social activity, and nutrition among others. Mediterranean diet, preprobiotics, and nutraceuticals containing bioactive molecules with antioxidant and anti-inflammatory properties are relevant. Antiprotein aggregation molecules whose mechanisms were described are important. Anti-inflammatory agents with anti-aggregation properties that help to control cognitive impairment, include quercetin, biocurcumin, rosemarinic acid, and Andean shilajit. Anthocyanidins, e.g., delphinidin, malvidin, and natural flavonoids, are also included. Quercetin and hydroxy-tyrosol are antiaging molecules and could have anti-AD properties. We emphasize the relevance of nutraceuticals as a main actor in the prevention and/or control of dementia and particularly AD.

The Therapeutic and Diagnostic Potential of Amyloid β Oligomers Selective Antibodies to Treat Alzheimer's Disease

Improvements have been made in the diagnosis of Alzheimer’s disease (AD), manifesting mostly in the development of in vivo imaging methods that allow for the detection of pathological changes in AD by magnetic resonance imaging (MRI) and positron emission tomography (PET) scans. Many of these imaging methods, however, use agents that probe amyloid fibrils and plaques–species that do not correlate well with disease progression and are not present at the earliest stages of the disease. Amyloid β oligomers (AβOs), rather, are now widely accepted as the Aβ species most germane to AD onset and progression. Here we report evidence further supporting the role of AβOs as pathological instigators of AD and introduce promising anti-AβO diagnostic probes capable of distinguishing the 5xFAD mouse model from wild type mice by PET and MRI. In a developmental study, Aβ oligomers in 5xFAD mice were found to appear at 3 months of age, just prior to the onset of memory dysfunction, and spread as memory worsened. The increase of AβOs is prominent in the subiculum and correlates with concomitant development of reactive astrocytosis. The impact of these AβOs on memory is in harmony with findings that intraventricular injection of synthetic AβOs into wild type mice induced hippocampal dependent memory dysfunction within 24 h. Compelling support for the conclusion that endogenous AβOs cause memory loss was found in experiments showing that intranasal inoculation of AβO-selective antibodies into 5xFAD mice completely restored memory function, measured 30–40 days post-inoculation. These antibodies, which were modified to give MRI and PET imaging probes, were able to distinguish 5xFAD mice from wild type littermates. These results provide strong support for the role of AβOs in instigating memory loss and salient AD neuropathology, and they demonstrate that AβO selective antibodies have potential both for therapeutics and for diagnostics.

New Frontiers in the Prevention, Diagnosis, and Treatment of Alzheimer's Disease

One of the major puzzles in medical research and public health systems worldwide is Alzheimer's disease (AD), reaching nowadays a prevalence near 50 million people. This is a multifactorial brain disorder characterized by progressive cognitive impairment, apathy, and mood and neuropsychiatric disorders. The main risk of AD is aging; a normal biological process associated with a continuum dynamic involving a gradual loss of people's physical capacities, but with a sound experienced view of life. Studies suggest that AD is a break from normal aging with changes in the powerful functional capacities of neurons as well as in the mechanisms of neuronal protection. In this context, an important path has been opened toward AD prevention considering that there are elements of nutrition, daily exercise, avoidance of toxic substances and drugs, an active social life, meditation, and control of stress, to achieve healthy aging. Here, we analyze the involvement of such factors and how to control environmental risk factors for a better quality of life. Prevention as well as innovative screening programs for early detection of the disease using reliable biomarkers are becoming critical to control the disease. In addition, the failure of traditional pharmacological treatments and search for new drugs has stimulated the emergence of nutraceutical compounds in the context of a "multitarget" therapy, as well as mindfulness approaches shown to be effective in the aging, and applied to the control of AD. An integrated approach involving all these preventive factors combined with novel pharmacological approaches should pave the way for the future control of the disease.

Diagnostic and Prognostic Laboratory Testing for Alzheimer Disease

This article focuses on current clinical laboratory testing to diagnose Alzheimer disease and monitor its progression throughout its disease course. Several clinically available tests focus on analysis of amyloid and tau levels in cerebrospinal fluid as well as autosomal dominant and risk factor genes. Although the current armament of clinical laboratory testing is limited by invasiveness of cerebrospinal fluid collection, rarity of autosomal dominant genetic mutations, and uncertainties of risk inherent in nonpenetrant genes, the field is poised to advance the clinical repertoire of laboratory diagnostic testing.

Molecular mechanisms in Alzheimer's disease and the impact of physical exercise with advancements in therapeutic approaches

Alzheimer's disease (AD) is one of the most common, severe neurodegenerative brain disorder characterized by the accumulation of amyloid-beta plaques, neurofibrillary tangles in the brain causing neural disintegration, synaptic dysfunction, and neuronal death leading to dementia. Although many US-FDA-approved drugs like Donepezil, Rivastigmine, Galantamine are available in the market, their consumption reduces only the symptoms of the disease but fails in potency to cure the disease. This disease affects many individuals with aging. Combating the disease tends to be very expensive. This review focuses on biochemical mechanisms in the neuron both at normal and AD state with relevance to the tau hypothesis, amyloid hypothesis, the risk factors influencing dementia, oxidative stress, and neuroinflammation altogether integrated with neurodegeneration. A brief survey is carried out on available biomarkers in the diagnosis of the disease, drugs used for the treatment, and the challenges in approaching therapeutic targets in inhibiting the disease pathologies. This review conjointly assesses the demerits with the inefficiency of drugs to reach targets, their side effects, and toxicity. Optimistically, this review directs on the advantageous strategies in using nanotechnology-based drug delivery systems to cross the blood-brain barrier for improving the efficacy of drugs combined with a novel neuronal stem cell therapy approach. Determinately, this review aims at the natural, non-therapeutic healing impact of physical exercise on different model organisms and the effect of safe neuromodulation treatments using repetitive Transcranial Magnetic Stimulation (rTMS), transcranial Electrical Stimulation (tES) in humans to control the disease pathologies prominent in enhancing the synaptic function.

Met and unmet care needs of home-living people with dementia in China: An observational study using the Camberwell Assessment of Need for the Elderly

Aim

The goal of the study was to investigate the patterns of needs in older individuals with mild‐to‐moderate dementia living at home using the Camberwell Assessment of Need for the Elderly questionnaire.

Methods

This was a cross‐sectional study. A total of 378 home‐living residents served as the sample. The Camberwell Assessment of Need for the Elderly questionnaire was used to analyze the needs of those receiving adequate interventions (met needs) and those without appropriate supports (unmet needs). Thereafter, the factors that correlated with total needs were determined using demographic characteristics.

Results

Persons with dementia (PWD) had a mean care needs of 18.5 ± 5.4 (range 5–35). Unmet needs were most common in caring for someone (65.1%), looking after the home (63.5%), self‐care (58.7%) and intimate relationships (44.4%) domains. Higher needs were significantly related to living with others than a spouse, longer length of diagnosis, older age and higher cognitive function.

Conclusion

Unmet needs are common in home‐living PWD. Home‐based dementia care can identify and address PWD's unmet needs by focusing on care recipients and caregivers to enable PWD to remain safely at home and improve their quality of life. Geriatr Gerontol Int 2021; 21: 102–107.

Mechanism of TREM2/DAP12 complex affecting β-amyloid plaque deposition in Alzheimer's disease modeled mice through mediating inflammatory response

To investigate the mechanism of TREM2/DAP12 complex in mediating inflammatory responses that affect β-amyloid plaque deposition in Alzheimer's disease (AD) modeled mice. We measured escape latency and platform crossing time using the Morris water maze image automatic acquisition and software analysis system in TREM2 and DAP12 microglia knockout AD model mouse. We monitored the deposition of Aβ plaques in the mouse hippocampus using Congo red staining and measured levels. of inflammatory factors IL-6 and TNF-α by ELISA. Newborn mice with TREM2 knockout were selected for primary microglia isolation and culture, and Aged oligomer Aβ1-42 was added to the microglial culture medium to simulate the AD environment in vivo. Co-immunoprecipitation assay was used to detect the interaction between DAP12 and TREM2, and measured the inflammatory response induced by lipopolysaccharide (LPS) in mice with TREM2 and DAP12 knockdown through adeno-associated virus in BV2 microglia. The escape latency of the AD model mice with TREM2 and DAP12 knockout was higher and the number of crossing platforms lower than in the control group, whereas Aβ deposition and levels of inflammatory factors were higher. In TREM2 knockout microglial cultured with Aβ1-42, levels of IL-6 and TNF-α increased. Immunoprecipation pull-down assays showed that TREM2 binds to the membrane receptor DAP12 to form a complex. Knockout of TREM2 or DAP12 can inhibit LPS-induced microglial inflammatory responses. The TREM2/DAP12 complex inhibits the microglial inflammatory response through the JNK signaling pathway, thereby reducing the deposition of Aβ plaques and attenuation the behavioral manifestation in a mouse AD model.

Hydroxytyrosol improves mitochondrial energetics of a cellular model of Alzheimer's disease

Mitochondrial energetic deficit is one of the hallmarks of neurodegenerative disorders, e.g. Alzheimer´s disease (AD). Adherence to a Mediterranean diet is associated with lower incidence of cognitive decline and AD and extra virgin olive oil's (poly)phenols such as oleuropein and hydroxytyrosol (HT) are being actively studied in this respect. In this study, we assessed the effects of HT on mitochondrial energetic dysfunction in the 7PA2 cells cellular model, i.e. one of the best cellular models of Aβ toxicity with a well-characterized mitochondrial dysfunction typically observed in AD. We report an increase of new mitochondria at 8 h post HT-treatment, which was followed by higher mitochondrial fusion. Further, ATP concentrations were significantly increased after 24 h of treatment with HT as compared with controls. Our data suggest that HT may revert the energetic deficit of a cellular model of AD by potentiating mitochondrial activity. Because HT is being proposed as dietary supplement or component of functional foods, future studies in appropriate animal models and - eventually - humans are warranted to further investigate its potential neuroprotective actions in AD.

Strategies Targeting Soluble β-Amyloid Oligomers and their Application to Early Diagnosis of Alzheimer's Disease

BACKGROUND

Alzheimer's Disease (AD) is the most common neurodegenerative disorder, and it is still incurable. Early diagnosis and intervention are crucial for delaying the onset and progression of the disease. Mounting evidence indicates that the neurotoxic effects might be attributed to Soluble β-Amyloid Oligomers (SAβO). The SAβO are believed to be neurotoxic peptides more predominant than Aβ plaques in the early stage, and their key role in AD is self-evident. Unfortunately, identification of SAβO proves to be difficult due to their heterogeneous and transient nature. In spite of many obstacles, multiple techniques have recently been developed to target SAβO effectively. This review focuses on the recent progress in the approaches towards SAβO detection in order to shed some light on the future development of SAβO assays.

METHODS

Literatures were obtained from the following libraries: Web of Science, PubMed, EPO, SIPO, USPTO. Articles were critically reviewed based on their titles, abstracts, and contents.

RESULTS

A total of 85 papers are referenced in the review. Results are divided into three categories based on the types of detection methods: small molecule fluorescence probes, oligomer-specific antibodies and electrochemical biosensors. Finally, the improvements and challenges of these approaches applied in the early diagnosis of AD were discussed.

CONCLUSION

This review article covers three kinds of strategies that could be translated into clinic practice and lead to earlier diagnosis and therapeutic interventions of AD.

Plasma isoprostanoids assessment as Alzheimer's disease progression biomarkers

Alzheimer's Disease (AD) is the most common neurodegenerative disease worldwide. So, there is a need to identify AD early diagnosis and monitoring biomarkers in blood samples. The aim of this study was to analyse the utility of lipid peroxidation biomarkers in AD progression evaluation. Participants (n = 19) were diagnosed with AD at early stages (Time 0, T0), and they were re-evaluated 2 years later (Time 1, T1). Plasma biomarkers from AD patients were determined at both times. Some analytes, such as dihomo-isoprostanes (17-epi-17-F2t-dihomo-IsoP, 17-F2t-dihomo-IsoP, Ent-7(RS)-7-F2t-dihomo-IsoP), and neuroprostanes (10-epi-10-F4t-NeuroP) showed very high probability of showing an increasing trend over time. Baseline values allowed to develop an affordable preliminary regression model to predict long-term cognitive status. So, some lipid peroxidation biomarkers would deserve consideration as useful progression AD biomarkers. The developed prediction model would constitute an important minimally invasive approach in AD personalized prognosis and perhaps could have some interest also in experimental treatments evaluation.

Clinical Utility of Plasma Lipid Peroxidation Biomarkers in Alzheimer's Disease Differential Diagnosis

BACKGROUND

Differential diagnosis of Alzheimer's disease (AD) is a complex task due to the clinical similarity among neurodegenerative diseases. Previous studies showed the role of lipid peroxidation in early AD development. However, the clinical validation of potential specific biomarkers in minimally invasive samples constitutes a great challenge in early AD diagnosis.

METHODS

Plasma samples from participants classified into AD (n = 138), non-AD (including MCI and other dementias not due to AD) (n = 70) and healthy (n = 50) were analysed. Lipid peroxidation compounds (isoprostanes, isofurans, neuroprostanes, neurofurans) were determined by ultra-performance liquid chromatography coupled with tandem mass spectrometry. Statistical analysis for biomarkers' clinical validation was based on Elastic Net.

RESULTS

A two-step diagnosis model was developed from plasma lipid peroxidation products to diagnose early AD specifically, and a bootstrap validated AUC of 0.74 was obtained.

CONCLUSION

A promising AD differential diagnosis model was developed. It was clinically validated as a screening test. However, further external validation is required before clinical application.

Molecular and Imaging Biomarkers in Alzheimer's Disease: A Focus on Recent Insights

Alzheimer’s disease (AD) is the most common neurodegenerative disease among the elderly, affecting millions of people worldwide and clinically characterized by a progressive and irreversible cognitive decline. The rapid increase in the incidence of AD highlights the need for an easy, efficient and accurate diagnosis of the disease in its initial stages in order to halt or delay the progression. The currently used diagnostic methods rely on measures of amyloid-β (Aβ), phosphorylated (p-tau) and total tau (t-tau) protein levels in the cerebrospinal fluid (CSF) aided by advanced neuroimaging techniques like positron emission tomography (PET) and magnetic resonance imaging (MRI). However, the invasiveness of these procedures and the high cost restrict their utilization. Hence, biomarkers from biological fluids obtained using non-invasive methods and novel neuroimaging approaches provide an attractive alternative for the early diagnosis of AD. Such biomarkers may also be helpful for better understanding of the molecular mechanisms underlying the disease, allowing differential diagnosis or at least prolonging the pre-symptomatic stage in patients suffering from AD. Herein, we discuss the advantages and limits of the conventional biomarkers as well as recent promising candidates from alternative body fluids and new imaging techniques.

The influence of Aβ-dependent and independent pathways on TDP-43 proteinopathy in Alzheimer's disease: a possible connection to LATE-NC

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that results from the accumulation of plaques by cleaved Aβ₄₂ peptides as well as neurofibrillary tangles of tau proteins. This accumulation triggers a complex cascade of cytotoxic, neuroinflammatory, and oxidative stresses that lead to neuronal death throughout the progression of the disease. Much of research in AD focused on the 2 pathologic proteins. Interestingly, another form of dementia with similar clinical manifestations of AD, but preferentially affected much older individuals, was termed as limbic-predominant age-related transactive response DNA-binding protein 43 (TDP-43) encephalopathy (LATE) and involved the cytotoxic intraneuronal deposition of phosphorylated TDP-43. TDP-43 proteinopathy was also found to be involved in AD pathology leading to the possibility that AD and LATE may share a common upstream etiology. This paper discusses the roles molecular pathways known in AD may have on influencing TDP-43 proteinopathy and the development of AD, LATE, or the 2 being comorbid with each other.

Metabolic syndrome exacerbates amyloid pathology in a comorbid Alzheimer's mouse model

Alzheimer's disease (AD) often coexists with other aging-associated diseases including obesity, diabetes, hypertension, and cardiovascular diseases. The early stage of these comorbidities is known as metabolic syndrome (MetS) which is highly prevalent in mid-life. An important cause of MetS is the deficiency of SIRT3, a mitochondrial deacetylase which enhances the functions of critical mitochondrial proteins, including metabolic enzymes, by deacetylation. Deletion of Sirt3 gene has been reported to result in the acceleration of MetS. In a recently published study, we demonstrated in the brain of Sirt3^-/- mice, downregulation of metabolic enzymes, insulin resistance and elevation of inflammatory markers including microglial proliferation. These findings suggested a novel pathway that could link SIRT3 deficiency to neuroinflammation, an important cause of Alzheimer's pathogenesis. Therefore, we hypothesized that MetS and amyloid pathology may interact through converging pathways of insulin resistance and neuroinflammation in comorbid AD. To investigate these interactions, we crossed Sirt3^-/- mice with APP/PS1 mice and successfully generated APP/PS1/Sirt3^-/- mice with amyloid pathology and MetS. In these comorbid AD mice, we observed exacerbation of insulin resistance, glucose intolerance, amyloid plaque deposition, markers of neuroinflammation, including elevated expression of IL-1β, TNF-α and Cox-2 at 8 months of age. There was also increased microglial proliferation and activation. Our observations suggest a novel mechanism by which MetS may interact with amyloid pathology during the cellular phase of AD. Therapeutic targeting of SIRT3 in AD with comorbidities may produce beneficial effects.