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Ageing Research Reviews Dec 2021Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in ageing, affecting around 46 million people worldwide but few treatments are currently... (Review)
Review
Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in ageing, affecting around 46 million people worldwide but few treatments are currently available. The etiology of AD is still puzzling, and new drugs development and clinical trials have high failure rates. Urgent outline of an integral (multi-target) and effective treatment of AD is needed. Accumulation of amyloid-β (Aβ) peptides is considered one of the fundamental neuropathological pillars of the disease, and its dyshomeostasis has shown a crucial role in AD onset. Therefore, many amyloid-targeted therapies have been investigated. Here, we will systematically review recent (from 2014) investigational, follow-up and review studies focused on anti-amyloid strategies to summarize and analyze their current clinical potential. Combination of anti-Aβ therapies with new developing early detection biomarkers and other therapeutic agents acting on early functional AD changes will be highlighted in this review. Near-term approval seems likely for several drugs acting against Aβ, with recent FDA approval of a monoclonal anti-Aβ oligomers antibody -aducanumab- raising hopes and controversies. We conclude that, development of oligomer-epitope specific Aβ treatment and implementation of multiple improved biomarkers and risk prediction methods allowing early detection, together with therapies acting on other factors such as hyperexcitability in early AD, could be the key to slowing this global pandemic.
Topics: Alzheimer Disease; Amyloid; Amyloid beta-Peptides; Biomarkers; Humans; Neurodegenerative Diseases
PubMed: 34687956
DOI: 10.1016/j.arr.2021.101496 -
International Journal of Molecular... Jan 2023Alzheimer's disease (AD) is a multifactorial, progressive, neurodegenerative disease typically characterized by memory loss, personality changes, and a decline in... (Review)
Review
Alzheimer's disease (AD) is a multifactorial, progressive, neurodegenerative disease typically characterized by memory loss, personality changes, and a decline in overall cognitive function. Usually manifesting in individuals over the age of 60, this is the most prevalent type of dementia and remains the fifth leading cause of death among Americans aged 65 and older. While the development of effective treatment and prevention for AD is a major healthcare goal, unfortunately, therapeutic approaches to date have yet to find a treatment plan that produces long-term cognitive improvement. Drugs that may be able to slow down the progression rate of AD are being introduced to the market; however, there has been no previous solution for preventing or reversing the disease-associated cognitive decline. Recent studies have identified several factors that contribute to the progression and severity of the disease: diet, lifestyle, stress, sleep, nutrient deficiencies, mental health, socialization, and toxins. Thus, increasing evidence supports dietary and other lifestyle changes as potentially effective ways to prevent, slow, or reverse AD progression. Studies also have demonstrated that a personalized, multi-therapeutic approach is needed to improve metabolic abnormalities and AD-associated cognitive decline. These studies suggest the effects of abnormalities, such as insulin resistance, chronic inflammation, hypovitaminosis D, hormonal deficiencies, and hyperhomocysteinemia, in the AD process. Therefore a personalized, multi-therapeutic program based on an individual's genetics and biochemistry may be preferable over a single-drug/mono-therapeutic approach. This article reviews these multi-therapeutic strategies that identify and attenuate all the risk factors specific to each affected individual. This article systematically reviews studies that have incorporated multiple strategies that target numerous factors simultaneously to reverse or treat cognitive decline. We included high-quality clinical trials and observational studies that focused on the cognitive effects of programs comprising lifestyle, physical, and mental activity, as well as nutritional aspects. Articles from PubMed Central, Scopus, and Google Scholar databases were collected, and abstracts were reviewed for relevance to the subject matter. Epidemiological, pathological, toxicological, genetic, and biochemical studies have all concluded that AD represents a complex network insufficiency. The research studies explored in this manuscript confirm the need for a multifactorial approach to target the various risk factors of AD. A single-drug approach may delay the progression of memory loss but, to date, has not prevented or reversed it. Diet, physical activity, sleep, stress, and environment all contribute to the progression of the disease, and, therefore, a multi-factorial optimization of network support and function offers a rational therapeutic strategy. Thus, a multi-therapeutic program that simultaneously targets multiple factors underlying the AD network may be more effective than a mono-therapeutic approach.
Topics: Humans; Alzheimer Disease; Neurodegenerative Diseases; Cognitive Dysfunction; Cognition; Memory Disorders
PubMed: 36675177
DOI: 10.3390/ijms24021659 -
Cells May 2023Blood biomarkers have been considered tools for the diagnosis, prognosis, and monitoring of Alzheimer's disease (AD). Although amyloid-β peptide (Aβ) and tau are... (Meta-Analysis)
Meta-Analysis Review
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.
Topics: Humans; Alzheimer Disease; Amyloid beta-Peptides; Biomarkers; Cognitive Dysfunction; Glial Fibrillary Acidic Protein
PubMed: 37174709
DOI: 10.3390/cells12091309 -
Neurology Mar 2020To test the hypothesis that distinct subtypes of Alzheimer disease (AD) exist and underlie the heterogeneity within AD, we conducted a systematic review and... (Meta-Analysis)
Meta-Analysis
OBJECTIVE
To test the hypothesis that distinct subtypes of Alzheimer disease (AD) exist and underlie the heterogeneity within AD, we conducted a systematic review and meta-analysis on AD subtype studies based on postmortem and neuroimaging data.
METHODS
EMBASE, PubMed, and Web of Science databases were consulted until July 2019.
RESULTS
Neuropathology and neuroimaging studies have consistently identified 3 subtypes of AD based on the distribution of tau-related pathology and regional brain atrophy: typical, limbic-predominant, and hippocampal-sparing AD. A fourth subtype, minimal atrophy AD, has been identified in several neuroimaging studies. Typical AD displays tau-related pathology and atrophy both in hippocampus and association cortex and has a pooled frequency of 55%. Limbic-predominant, hippocampal-sparing, and minimal atrophy AD had a pooled frequency of 21%, 17%, and 15%, respectively. Between-subtype differences were found in age at onset, age at assessment, sex distribution, years of education, global cognitive status, disease duration, APOE ε4 genotype, and CSF biomarker levels.
CONCLUSION
We identified 2 core dimensions of heterogeneity: typicality and severity. We propose that these 2 dimensions determine individuals' belonging to one of the AD subtypes based on the combination of protective factors, risk factors, and concomitant non-AD brain pathologies. This model is envisioned to aid with framing hypotheses, study design, interpretation of results, and understanding mechanisms in future subtype studies. Our model can be used along the A/T/N classification scheme for AD biomarkers. Unraveling the heterogeneity within AD is critical for implementing precision medicine approaches and for ultimately developing successful disease-modifying drugs for AD.
Topics: Alzheimer Disease; Humans
PubMed: 32047067
DOI: 10.1212/WNL.0000000000009058 -
Atencion Primaria May 2020The objective of this review is to analyze through a the scientific evidence about the effects of physical activity in patients with Alzheimer's disease (AD) as a...
OBJECTIVE
The objective of this review is to analyze through a the scientific evidence about the effects of physical activity in patients with Alzheimer's disease (AD) as a preventive and non-pharmacological treatment.
DESIGN
Systematic review.
DATA SOURCES
We have identified articles from Pubmed, Science Direct, Medline and Scopus databases, with the keywords Alzheimer, Exercise, Neuroimaging, MRI, PET y Physical Activity. Selected articles: We included those studies that evaluated the effects of physical activity on Alzheimer's disease and those which also included magnetic resonance imaging or positron emission tomography with Pittsburg Compound B marker (PiB) analyzing brain atrophy or increase of the beta-amyloid deposit respectively. We excluded studies including other types of dementia, different of AD. We also excluded articles which not included neuroimaging tests, single cases or non-English language articles.
DATA EXTRACTION
The PRISMA quality scale was used for the critical lecture of the studies. The researchers independently assessed the articles and the discrepancies were resolved by consensus.
RESULTS
We identified 75 articles, of which 23 were finally included in the review.
CONCLUSIONS
Most of the studies included do not allow us to know the impact of physical exercise on cognition and the cerebral structural-functional changes in patients at risk of developing AD or in patients who already have the disease. Without being able to rule out a possible beneficial effect, more studies are needed with a better design and methodological rigor that allows a better known about this association.
Topics: Alzheimer Disease; Amyloid beta-Peptides; Atrophy; Brain; Exercise; Humans; Magnetic Resonance Imaging; Neuroimaging; Positron-Emission Tomography
PubMed: 31153668
DOI: 10.1016/j.aprim.2018.09.010 -
Journal of Alzheimer's Disease : JAD 2023Pre-clinical evidence implicates oral bacteria in the pathogenesis of Alzheimer's disease (AD), while clinical studies show diverse results. (Meta-Analysis)
Meta-Analysis
BACKGROUND
Pre-clinical evidence implicates oral bacteria in the pathogenesis of Alzheimer's disease (AD), while clinical studies show diverse results.
OBJECTIVE
To comprehensively assess the association between oral bacteria and AD with clinical evidence.
METHODS
Studies investigating the association between oral bacteria and AD were identified through a systematic search of six databases PubMed, Embase, Cochrane Central Library, Scopus, ScienceDirect, and Web of Science. Methodological quality ratings of the included studies were performed. A best evidence synthesis was employed to integrate the results. When applicable, a meta-analysis was conducted using a random-effect model.
RESULTS
Of the 16 studies included, ten investigated periodontal pathobionts and six were microbiome-wide association studies. Samples from the brain, serum, and oral cavity were tested. We found over a ten-fold and six-fold increased risk of AD when there were oral bacteria (OR = 10.68 95% CI: 4.48-25.43; p < 0.00001, I2 = 0%) and Porphyromonas gingivalis (OR = 6.84 95% CI: 2.70-17.31; p < 0.0001, I2 = 0%) respectively in the brain. While AD patients exhibited lower alpha diversity of oral microbiota than healthy controls, the findings of bacterial communities were inconsistent among studies. The best evidence synthesis suggested a moderate level of evidence for an overall association between oral bacteria and AD and for oral bacteria being a risk factor for AD.
CONCLUSION
Current evidence moderately supports the association between oral bacteria and AD, while the association was strong when oral bacteria were detectable in the brain. Further evidence is needed to clarify the interrelationship between both individual species and bacterial communities and the development of AD.
Topics: Humans; Alzheimer Disease; Cognitive Dysfunction; Risk Factors; Microbiota; Porphyromonas gingivalis
PubMed: 36404545
DOI: 10.3233/JAD-220627 -
Ageing Research Reviews Sep 2023The risk-benefit profile of anti-Aβ monoclonal antibodies (mAbs) in Alzheimer's disease (AD) remains unclear, especially concerning their safety and overall effects on... (Meta-Analysis)
Meta-Analysis Review
Efficacy and safety of anti-amyloid-β monoclonal antibodies in current Alzheimer's disease phase III clinical trials: A systematic review and interactive web app-based meta-analysis.
The risk-benefit profile of anti-Aβ monoclonal antibodies (mAbs) in Alzheimer's disease (AD) remains unclear, especially concerning their safety and overall effects on AD progression and cognitive function. Here, we investigated cognitive, biomarker and side effects of anti-Aβ mAbs in large phase III randomized placebo-controlled clinical trials (RCTs) in sporadic AD. The search was performed on Google Scholar, PubMed and ClinicalTrials.gov by applying Jadad score to evaluate the methodological quality of the reports. Studies were excluded if they scored < 3 on Jadad scale or if they analyzed less than 200 sporadic AD patients. We followed PRISMA guidelines and DerSimonian-Laird random-effects model in R. Primary outcomes were cognitive: AD Assessment Scale-Cognitive Subscale (ADAS-Cog), Mini Mental State Examination (MMSE) and Clinical Dementia Rating Scale-sum of Boxes (CDR-SB). Secondary and tertiary outcomes included biomarkers of Aβ and tau pathology, adverse events, and performance on Alzheimer's Disease Cooperative Study - Activities of Daily Living Scale. The meta-analysis included 14,980 patients in 14 studies and four mAbs: Bapineuzumab, Aducanumab, Solanezumab and Lecanemab. The results of this study suggest that anti-Aβ mAbs statistically improved cognitive and biomarker outcomes, particularly Aducanumab and Lecanemab. However, while cognitive effects were of small effect sizes, these drugs considerably increased risk of side effects such as Amyloid Related Imaging Abnormalities (ARIA), especially in APOE-ε4 carriers. Meta-regression revealed that higher (better) baseline MMSE score was associated with improved ADAS Cog and CDR-SB. In order to improve reproducibility and update the analysis in the future, we developed AlzMeta.app, web-based application freely available at https://alzmetaapp.shinyapps.io/alzmeta/.
Topics: Humans; Alzheimer Disease; Reproducibility of Results; Activities of Daily Living; Mobile Applications; Amyloid beta-Peptides; Antibodies, Monoclonal; Biomarkers
PubMed: 37423541
DOI: 10.1016/j.arr.2023.102012 -
Neurological Sciences : Official... Jul 2022To explore the pathogenetic hypothesis provided to explain the comorbidity of anxious and depressive symptomatology and AD and to assess the association between anxious... (Review)
Review
OBJECTIVES
To explore the pathogenetic hypothesis provided to explain the comorbidity of anxious and depressive symptomatology and AD and to assess the association between anxious and depressive symptoms and the AD-related cognitive impairment.
METHODS
In October 2020 and March 2021, PsycINFO, Embase, Ovid, and CINAHL were searched for peer-reviewed original articles investigating anxiety and/or depression in AD.
RESULTS
A total of 14,760 studies were identified and 34 papers on AD patients were included in the review. Suggested biological causes of depression and anxiety in AD include higher strychnine-sensitive glycine receptor (GlyRS) functioning and selective reduction of N-methyl-D-aspartate (NMDA) receptor NR2A density, cortical and limbic atrophy, lower resting cortical metabolism, lower CSF Aβ42 and higher t-tau and p-tau levels, and neuritic plaques. At the same time, dysthymia arises in the early stages of AD as an emotional reaction to the progressive cognitive decline and can cause it; anxiety can appear as an initial compensating behaviour; and depression might be related to AD awareness and loss of functional abilities. Affective symptoms and the expression of the depressive symptoms tend to reduce as AD progresses.
CONCLUSION
The neurodegeneration of areas and circuits dealing with emotions can elicit anxiety and depression in AD. In the early stages of the disease, anxiety and depression could arise as a psychological reaction to AD and due to coping difficulties. In late AD stages, the cognitive impairment reduces the emotional responses and their expression. Anxiety and depression are more intense in early-onset AD, due to the major impact of AD on the individual.
Topics: Alzheimer Disease; Anxiety; Anxiety Disorders; Biomarkers; Cognitive Dysfunction; Depression; Humans; Receptors, N-Methyl-D-Aspartate
PubMed: 35461471
DOI: 10.1007/s10072-022-06068-x -
International Journal of Environmental... Nov 2022Declines in activities of daily living (ADL) and instrumental activities of daily living (IADL) performances due to cognitive impairments hinder mild cognitive... (Meta-Analysis)
Meta-Analysis Review
Declines in activities of daily living (ADL) and instrumental activities of daily living (IADL) performances due to cognitive impairments hinder mild cognitive impairment (MCI) and Alzheimer's disease (AD) patients' independent and safe daily lives. In order to prevent and treat this, several cognitive interventions have been implemented, but their ecological validity was not ensured due to that their contents are far from real life. Virtual reality (VR) can resemble real life with immersive stimuli, but there have been few studies confirming its ecological effects on ADL and IADL. Therefore, this study conducted a meta-analysis of VR-based cognitive training to investigate its ecological effects on ADL and IADL in MCI and AD patients. From February 2012 to February 2022, a search was conducted for articles published in PubMed, Cochrane, Science Direct, and Web of Science. Quality assessment was assessed by the PEDro scale, and the Cochrane Collaboration tool was used to assess risk of bias. Publication bias was assessed by Egger's regression. Five studies that met inclusion criteria were included in this study. The VR-based cognitive training showed significant effects on ADL and IADL in both MCI and AD patients. When comparing effects in each group, both MCI and AD patients showed significant effects on ADL and IADL, but MCI patients showed lower effects on ADL and IADL than AD patients. The results indicated that VR-based cognitive training would be beneficial to improve ADL and IADL in MCI and AD patients, suggesting that VR-based cognitive training is ecologically valid.
Topics: Humans; Activities of Daily Living; Alzheimer Disease; Cognitive Training; Cognitive Dysfunction; Virtual Reality; Neuropsychological Tests
PubMed: 36497946
DOI: 10.3390/ijerph192315875 -
Journal of Neurochemistry Mar 2021Similar to dementia, the risk for developing type 2 diabetes mellitus (T2DM) increases with age, and T2DM also increases the risk for dementia, particularly Alzheimer's...
Similar to dementia, the risk for developing type 2 diabetes mellitus (T2DM) increases with age, and T2DM also increases the risk for dementia, particularly Alzheimer's disease (AD). Although T2DM is primarily a peripheral disorder and AD is a central nervous system disease, both share some common features as they are chronic and complex diseases, and both show involvement of oxidative stress and inflammation in their progression. These characteristics suggest that T2DM may be associated with AD, which gave rise to a new term, type 3 diabetes (T3DM). In this study, we searched for matching peripheral proteomic biomarkers of AD and T2DM based in a systematic review of the available literature. We identified 17 common biomarkers that were differentially expressed in both patients with AD or T2DM when compared with healthy controls. These biomarkers could provide a useful workflow for screening T2DM patients at risk to develop AD.
Topics: Alzheimer Disease; Animals; Biomarkers; Diabetes Mellitus, Type 2; Humans; Proteomics
PubMed: 32909269
DOI: 10.1111/jnc.15166