-
Molecular Neurobiology Sep 2019Currently there are 850,000 people with Alzheimer's disease in the UK, with an estimated rise to 1.1 million by 2025. Alzheimer's disease is characterised by the...
Currently there are 850,000 people with Alzheimer's disease in the UK, with an estimated rise to 1.1 million by 2025. Alzheimer's disease is characterised by the accumulation of amyloid-beta plaques and hyperphosphorylated tau in the brain causing a progressive decline in cognitive impairment. Small non-coding microRNA (miRNA) sequences have been found to be deregulated in the peripheral blood of Alzheimer patients. A systematic review was conducted to extract all miRNA found to be significantly deregulated in the peripheral blood. These deregulated miRNAs were cross-referenced against the miRNAs deregulated in the brain at Braak Stage III. This resulted in a panel of 10 miRNAs (hsa-mir-107, hsa-mir-26b, hsa-mir-30e, hsa-mir-34a, hsa-mir-485, hsa-mir200c, hsa-mir-210, hsa-mir-146a, hsa-mir-34c, and hsa-mir-125b) hypothesised to be deregulated early in Alzheimer's disease, nearly 20 years before the onset of clinical symptoms. After network analysis of the 10 miRNAs, they were found to be associated with the immune system, cell cycle, gene expression, cellular response to stress, neuron growth factor signalling, wnt signalling, cellular senescence, and Rho GTPases.
Topics: Alzheimer Disease; Animals; Biomarkers; Brain; Gene Regulatory Networks; Humans; MicroRNAs
PubMed: 30734227
DOI: 10.1007/s12035-019-1500-y -
Journal of Medical Internet Research Aug 2019Among areas that have challenged the progress of dementia care has been the assessment of change in symptoms over time. Digital biomarkers are defined as objective,...
Current State of Digital Biomarker Technologies for Real-Life, Home-Based Monitoring of Cognitive Function for Mild Cognitive Impairment to Mild Alzheimer Disease and Implications for Clinical Care: Systematic Review.
BACKGROUND
Among areas that have challenged the progress of dementia care has been the assessment of change in symptoms over time. Digital biomarkers are defined as objective, quantifiable, physiological, and behavioral data that are collected and measured by means of digital devices, such as embedded environmental sensors or wearables. Digital biomarkers provide an alternative assessment approach, as they allow objective, ecologically valid, and long-term follow-up with continuous assessment. Despite the promise of a multitude of sensors and devices that can be applied, there are no agreed-upon standards for digital biomarkers, nor are there comprehensive evidence-based results for which digital biomarkers may be demonstrated to be most effective.
OBJECTIVE
In this review, we seek to answer the following questions: (1) What is the evidence for real-life, home-based use of technologies for early detection and follow-up of mild cognitive impairment (MCI) or dementia? And (2) What transformation might clinicians expect in their everyday practices?
METHODS
A systematic search was conducted in PubMed, Cochrane, and Scopus databases for papers published from inception to July 2018. We searched for studies examining the implementation of digital biomarker technologies for mild cognitive impairment or mild Alzheimer disease follow-up and detection in nonclinic, home-based settings. All studies that included the following were examined: community-dwelling older adults (aged 65 years or older); cognitively healthy participants or those presenting with cognitive decline, from subjective cognitive complaints to early Alzheimer disease; a focus on home-based evaluation for noninterventional follow-up; and remote diagnosis of cognitive deterioration.
RESULTS
An initial sample of 4811 English-language papers were retrieved. After screening and review, 26 studies were eligible for inclusion in the review. These studies ranged from 12 to 279 participants and lasted between 3 days to 3.6 years. Most common reasons for exclusion were as follows: inappropriate setting (eg, hospital setting), intervention (eg, drugs and rehabilitation), or population (eg, psychiatry and Parkinson disease). We summarized these studies into four groups, accounting for overlap and based on the proposed technological solutions, to extract relevant data: (1) data from dedicated embedded or passive sensors, (2) data from dedicated wearable sensors, (3) data from dedicated or purposive technological solutions (eg, games or surveys), and (4) data derived from use of nondedicated technological solutions (eg, computer mouse movements).
CONCLUSIONS
Few publications dealt with home-based, real-life evaluations. Most technologies were far removed from everyday life experiences and were not mature enough for use under nonoptimal or uncontrolled conditions. Evidence available from embedded passive sensors represents the most relatively mature research area, suggesting that some of these solutions could be proposed to larger populations in the coming decade. The clinical and research communities would benefit from increasing attention to these technologies going forward.
Topics: Accelerometry; Aged; Alzheimer Disease; Automobile Driving; Biomarkers; Cognition; Cognitive Dysfunction; Disease Progression; Early Diagnosis; Geographic Information Systems; Humans; Independent Living; Surveys and Questionnaires; Technology; Telemedicine; Wearable Electronic Devices
PubMed: 31471958
DOI: 10.2196/12785 -
Accelerated Brain Volume Loss Caused by Anti-β-Amyloid Drugs: A Systematic Review and Meta-analysis.Neurology May 2023To evaluate brain volume changes caused by different subclasses of anti-β-amyloid (Aβ) drugs trailed in patients with Alzheimer disease. (Meta-Analysis)
Meta-Analysis
BACKGROUND AND OBJECTIVES
To evaluate brain volume changes caused by different subclasses of anti-β-amyloid (Aβ) drugs trailed in patients with Alzheimer disease.
METHODS
PubMed, Embase, and ClinicalTrials.gov databases were searched for clinical trials of anti-Aβ drugs. This systematic review and meta-analysis included adults enrolled in randomized controlled trials of anti-Aβ drugs (n = 8,062-10,279). The inclusion criteria were as follows: (1) randomized controlled trials of patients treated with anti-Aβ drugs that have demonstrated to favorably change at least one biomarker of pathologic Aβ and (2) detailed MRI data sufficient to assess the volumetric changes in at least one brain region. MRI brain volumes were used as the primary outcome measure; brain regions commonly reported include hippocampus, lateral ventricle, and whole brain. Amyloid-related imaging abnormalities (ARIAs) were investigated when reported in clinical trials. Of the 145 trials reviewed, 31 were included in the final analyses.
RESULTS
A meta-analysis on the highest dose of each trial on hippocampus, ventricle, and whole brain revealed drug-induced acceleration of volume changes that varied by anti-Aβ drug class. Secretase inhibitors accelerated atrophy to the hippocampus (Δ placebo - Δ drug: -37.1 µL [19.6% more than placebo]; 95% CI -47.0 to -27.1) and whole brain (Δ placebo - Δ drug: -3.3 mL [21.8% more than placebo]; 95% CI -4.1 to 2.5). Conversely, ARIA-inducing monoclonal antibodies accelerated ventricular enlargement (Δ placebo - Δ drug: +2.1 mL [38.7% more than placebo]; 95% CI 1.5-2.8) where a striking correlation between ventricular volume and ARIA frequency was observed ( = 0.86, = 6.22 × 10). Mild cognitively impaired participants treated with anti-Aβ drugs were projected to have a material regression toward brain volumes typical of Alzheimer dementia ∼8 months earlier than if they were untreated.
DISCUSSION
These findings reveal the potential for anti-Aβ therapies to compromise long-term brain health by accelerating brain atrophy and provide new insight into the adverse impact of ARIA. Six recommendations emerge from these findings.
Topics: Adult; Humans; Amyloid beta-Peptides; Alzheimer Disease; Antibodies, Monoclonal; Brain; Atrophy
PubMed: 36973044
DOI: 10.1212/WNL.0000000000207156 -
Sleep Medicine Reviews Apr 2020Increasing evidence links cognitive-decline and Alzheimer's disease (AD) to various sleep disorders, including obstructive sleep apnea (OSA). With increasing age, there...
Increasing evidence links cognitive-decline and Alzheimer's disease (AD) to various sleep disorders, including obstructive sleep apnea (OSA). With increasing age, there are substantial differences in OSA's prevalence, associated comorbidities and phenotypic presentation. An important question for sleep and AD researchers is whether OSA's heterogeneity results in varying cognitive-outcomes in older-adults compared to middle-aged adults. In this review, we systematically integrated research examining OSA and cognition, mild cognitive-impairment (MCI) and AD/AD biomarkers; including the effects of continuous positive airway pressure (CPAP) treatment, particularly focusing on characterizing the heterogeneity of OSA and its cognitive-outcomes. Broadly, in middle-aged adults, OSA is often associated with mild impairment in attention, memory and executive function. In older-adults, OSA is not associated with any particular pattern of cognitive-impairment at cross-section; however, OSA is associated with the development of MCI or AD with symptomatic patients who have a higher likelihood of associated disturbed sleep/cognitive-impairment driving these findings. CPAP treatment may be effective in improving cognition in OSA patients with AD. Recent trends demonstrate links between OSA and AD-biomarkers of neurodegeneration across all age-groups. These distinct patterns provide the foundation for envisioning better characterization of OSA and the need for more sensitive/novel sleep-dependent cognitive assessments to assess OSA-related cognitive-impairment.
Topics: Age Factors; Alzheimer Disease; Biomarkers; Cognition; Cognitive Dysfunction; Continuous Positive Airway Pressure; Humans; Interdisciplinary Research; Sleep Apnea, Obstructive; Sleep Wake Disorders
PubMed: 31881487
DOI: 10.1016/j.smrv.2019.101250 -
Life Sciences Nov 2023A diverse and stable microbiota promotes a healthy state, nevertheless, an imbalance in gut or oral bacterial composition, called dysbiosis, can cause gastrointestinal... (Review)
Review
A diverse and stable microbiota promotes a healthy state, nevertheless, an imbalance in gut or oral bacterial composition, called dysbiosis, can cause gastrointestinal disorders, systemic inflammatory states and oxidative stress, among others. Recently, gut and oral dysbiosis has been linked to Alzheimer's disease (AD), which is considered the most common form of dementia and a public health priority due to its high prevalence and incidence. The aim of this review is to highlight the implications of gut and oral microbiota in the neuroinflammation characteristic of AD pathology and the subsequent cognitive impairment. It is a systematic review of the current literature obtained by searching the PubMed, Web of Science and Scopus databases. The characteristic intestinal dysbiosis in AD patients leads to increased permeability of the intestinal barrier and activates immune cells in the central nervous system due to translocation of microbiota-derived metabolites and/or bacteria into the circulation leading to increased neuroinflammation and neuronal loss, thus generating the cognitive impairment characteristic of AD. The presence in the central nervous system of Porphyromonas gingivalis can cause an increased neuroinflammation and beta-amyloid peptide accumulation.
Topics: Humans; Alzheimer Disease; Gastrointestinal Microbiome; Neuroinflammatory Diseases; Dysbiosis; Microbiota; Inflammation; Bacteria; Brain
PubMed: 37793482
DOI: 10.1016/j.lfs.2023.122132 -
Neurologia Mar 2021Risk factors for dementia include genetic factors, aging, environmental factors, certain diseases, and unhealthy lifestyle; most types of dementia share a common chronic... (Review)
Review
INTRODUCTION
Risk factors for dementia include genetic factors, aging, environmental factors, certain diseases, and unhealthy lifestyle; most types of dementia share a common chronic systemic inflammatory phenotype. Psoriasis is also considered to be a chronic systemic inflammatory disease. It has been suggested that psoriasis may also contribute to the risk of dementia. The aim of this study was to systematically review the literature on the association between psoriasis and dementia.
DEVELOPMENT
Articles were selected according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched the PubMed and Web of Science databases to identify articles published in peer-reviewed journals and studying the association between psoriasis and dementia. Studies meeting the inclusion criteria were reviewed. We used the Newcastle-Ottawa Scale to assess the quality of each study. After applying the inclusion and exclusion criteria, we included 8 studies for review, 3 of which were found to present a higher risk of bias. Six of the 8 studies supported the hypothesis that prior diagnosis of psoriasis increases the risk of dementia; one study including only a few cases reported that psoriasis decreased the risk of dementia, and one study including relatively young patients found no significant association between psoriasis and the risk of dementia.
CONCLUSION
Most studies included in this review supported the hypothesis that psoriasis constitutes a risk factor for dementia. However, well-designed stratified cohort studies assessing both psoriasis severity and treatment status are still required to determine the real effect of psoriasis on the risk of dementia and its subtypes.
PubMed: 33771384
DOI: 10.1016/j.nrl.2020.12.007 -
Human Brain Mapping Jun 2021Resting-state fMRI (rs-fMRI) detects functional connectivity (FC) abnormalities that occur in the brains of patients with Alzheimer's disease (AD) and mild cognitive...
Resting-state fMRI (rs-fMRI) detects functional connectivity (FC) abnormalities that occur in the brains of patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). FC of the default mode network (DMN) is commonly impaired in AD and MCI. We conducted a systematic review aimed at determining the diagnostic power of rs-fMRI to identify FC abnormalities in the DMN of patients with AD or MCI compared with healthy controls (HCs) using machine learning (ML) methods. Multimodal support vector machine (SVM) algorithm was the commonest form of ML method utilized. Multiple kernel approach can be utilized to aid in the classification by incorporating various discriminating features, such as FC graphs based on "nodes" and "edges" together with structural MRI-based regional cortical thickness and gray matter volume. Other multimodal features include neuropsychiatric testing scores, DTI features, and regional cerebral blood flow. Among AD patients, the posterior cingulate cortex (PCC)/Precuneus was noted to be a highly affected hub of the DMN that demonstrated overall reduced FC. Whereas reduced DMN FC between the PCC and anterior cingulate cortex (ACC) was observed in MCI patients. Evidence indicates that the nodes of the DMN can offer moderate to high diagnostic power to distinguish AD and MCI patients. Nevertheless, various concerns over the homogeneity of data based on patient selection, scanner effects, and the variable usage of classifiers and algorithms pose a challenge for ML-based image interpretation of rs-fMRI datasets to become a mainstream option for diagnosing AD and predicting the conversion of HC/MCI to AD.
Topics: Alzheimer Disease; Cognitive Dysfunction; Connectome; Humans; Machine Learning; Magnetic Resonance Imaging; Predictive Value of Tests
PubMed: 33942449
DOI: 10.1002/hbm.25369 -
International Journal of Molecular... Jun 2023Alzheimer's Disease (AD) is a progressive neurodegenerative disorder characterised by cognitive impairment, and amyloid-β plaques and neurofibrillary tau tangles at... (Review)
Review
Alzheimer's Disease (AD) is a progressive neurodegenerative disorder characterised by cognitive impairment, and amyloid-β plaques and neurofibrillary tau tangles at neuropathology. Capsaicin is a spicy-tasting compound found in chili peppers, with anti-inflammatory, antioxidant, and possible neuroprotective properties. Capsaicin intake has been associated with greater cognitive function in humans, and attenuating aberrant tau hyperphosphorylation in a rat model of AD. This systematic review discusses the potential of capsaicin in improving AD pathology and symptoms. A systematic analysis was conducted on the effect of capsaicin on AD-associated molecular changes, cognitive and behaviour resulting in 11 studies employing rodents and/or cell cultures, which were appraised with the Cochrane Risk of Bias tool. Ten studies showed capsaicin attenuated tau deposition, apoptosis, and synaptic dysfunction; was only weakly effective on oxidative stress; and had conflicting effects on amyloid processing. Eight studies demonstrated improved spatial and working memory, learning, and emotional behaviours in rodents following capsaicin treatment. Overall, capsaicin showed promise in improving AD-associated molecular, cognitive, and behavioural changes in cellular and animal models, and further investigations are recommended to test the readily available bioactive, capsaicin, to treat AD.
Topics: Humans; Rats; Animals; Alzheimer Disease; Capsaicin; Amyloid beta-Peptides; Neurofibrillary Tangles; Cognition; tau Proteins; Disease Models, Animal
PubMed: 37373321
DOI: 10.3390/ijms241210176 -
Journal of the American Medical... Jul 2021An increasing reliance on telemedicine for older adults with cognitive impairment requires a better understanding of the barriers and facilitators for this unique... (Review)
Review
OBJECTIVES
An increasing reliance on telemedicine for older adults with cognitive impairment requires a better understanding of the barriers and facilitators for this unique patient population.
DESIGN
The study team queried PubMed, Embase, the Cochrane Library, PsycINFO, CINAHL, Scopus, and ClinicalTrials.gov on May 1, 2020, for studies in English published from January 2010 to May 2020.
SETTING AND PARTICIPANTS
We conducted a systematic review of articles investigating the use of telemedicine among older adults with Alzheimer's disease and related dementia (ADRD) or mild cognitive impairment (MCI) that focused on the patient and care partner perspectives.
METHODS
Telemedicine encounter purpose, technological requirements, and findings regarding sensory needs were extracted. The Cochrane Collaboration's Risk of Bias Tool was applied for quality assessment.
RESULTS
The search yielded 3551 abstracts, from which 90 articles were reviewed and 17 were included. The purpose of telemedicine encounters included routine care, cognitive assessment, and telerehabilitation. All studies reported successful implementation of telemedicine, supported by patient and care partner satisfaction, similar results on cognitive assessment and diagnosis compared to in-person visits, and improvement in outcome measures following rehabilitation. Sixteen studies relied on staff and care partners to navigate technologies. Six studies reported participants reporting difficulty hearing the provider during the telemedicine visits. Five studies excluded participants with visual or hearing impairment because of the potential difficulty of using telemedicine technology. No studies reported technological adaptations to account for sensory impairment.
CONCLUSIONS AND IMPLICATIONS
Telemedicine is well received among patients and care partners, but successful delivery incorporates support staff and the care partners to navigate technologies. The exclusion of older adults with sensory impairment, especially given that it is highly prevalent, in developing telemedicine systems may further exacerbate access to care in this population. Adapting technologies for sensory needs is critical to the advancement of accessible dementia care through telemedicine.
Topics: Aged; Alzheimer Disease; Cognitive Dysfunction; Humans; Telemedicine
PubMed: 33887231
DOI: 10.1016/j.jamda.2021.03.015 -
Ageing Research Reviews Dec 2022This study aimed to evaluate the bidirectional association between the kidney dysfunction and the brain health, including structural and functional abnormalities. (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
This study aimed to evaluate the bidirectional association between the kidney dysfunction and the brain health, including structural and functional abnormalities.
DESIGN
Systematic review and meta-analysis with network meta-analysis for outcomes with different estimated glomerular filtration rate (eGFR) ranges.
DATA SOURCES
PubMed, Embase database, Cochrane library and Web of Science (up to Dec. 2021).
ELIGIBILITY CRITERIA FOR SELECTING STUDIES
Longitudinal studies that provided evidence of the impact of kidney function estimated from eGFR and urine albumin-to-creatinine ratio (UACR) or chronic kidney disease (CKD) on structural and functional brain abnormalities, and those that provided evidence of the opposite relationship. Studies with study population mean age under 18 years old were excluded.
MAIN OUTCOME MEASURES
Two independent reviewers screened the included studies, extracted the data, and assessed the risk of bias. We performed a random-effects meta-analysis and a network meta-analysis for outcomes with compatible data. We assessed the risk of bias using the Newcastle-Ottawa Quality Assessment Scale criteria (NOS). Subgroup and sensitivity analyses were conducted to explore heterogeneity in the meta-analyses. Inconsistency analyses using the node-splitting method were performed to confirm the results of network meta-analysis.
RESULTS
A total of 53 studies with 3037,357 participants were included in the current systematic review. Among these, 16 provided evidence of structural brain abnormalities, and 38 provided evidence of cognitive impairment and dementia. Analysis of evidence of categorical kidney function showed a positive association between kidney dysfunction and cerebral small vessel disease (cSVD) (relative risk (RR) 1.77, 95% confidence interval (CI) 1.40-2.24, I = 0.0%), but such results were not found in the analyses of evidence where the kidney function was measured as a continuous variable. Meanwhile, analysis of 28 prior longitudinal studies with 194 compatible sets of data showed that the worse kidney function as categorical variables was related to a greater risk of global brain cognitive disorder (RR 1.28, 95% CI 1.20-1.36, I = 82.5%).
CONCLUSIONS
In this systematic review and meta-analysis, we found a positive association between CKD and functional brain disorders. However, the relationship between the kidney dysfunction and structural abnormalities in the brain remains controversial. As for the opposite relationship, structural brain abnormalities, especially cerebral microbleeds and silent infarction, but not functional brain abnormalities, are associated with worse renal function. In addition, a higher UACR, but not a lower eGFR, was associated with a higher risk of Alzheimer's disease and vascular dementia.
Topics: Humans; Adolescent; Brain; Cohort Studies; Alzheimer Disease; Renal Insufficiency, Chronic; Kidney
PubMed: 36374833
DOI: 10.1016/j.arr.2022.101762