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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 -
Revista de Neurologia Dec 2017Alzheimer's disease (AD) is a neurodegenerative disease which involves, among other manifestations, a progressive deterioration of memory and language, as well as...
INTRODUCTION
Alzheimer's disease (AD) is a neurodegenerative disease which involves, among other manifestations, a progressive deterioration of memory and language, as well as behavioral disorders. In addition to non-curative pharmacological therapies, for the last years, music therapy has been developed as an effective non-pharmacological therapy in order to relieve many of these manifestations.
AIM
To analyze the recent scientific evidence about the effect of music therapy on cognitive and behavioral symptoms in patients with AD.
PATIENTS AND METHODS
A systematic review has been carried out by means of a bibliographical research using the database PubMed and Science Direct. The key words used for this search were 'Alzheimer's disease' and 'music therapy', as well as the boolean operator 'AND'. We selected those publications between January 2006 and December 2016 and after inclusion criteria, 21 publications were selected.
RESULTS
This systematic review has demonstrated the beneficial impact of music therapy on cognition (memory, attention, language), emotion and behavior (anxiety, depression and agitation) in AD patients.
CONCLUSIONS
Music therapy constitutes a non-pharmacological therapy effective for some cognitive, emotional and behavioral symptoms in patients with AD. However, further investigations and more evidence in this field are needed to claim conclusively the impact of music therapy on this disease.
Topics: Alzheimer Disease; Behavior; Cognition; Emotions; Humans; Language; Memory; Music Therapy; Quality of Life; Treatment Outcome
PubMed: 29235615
DOI: No ID Found -
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 -
Epidemiology (Cambridge, Mass.) Sep 2016Engaging in late-life cognitive activity is often proposed as a strategy to delay or prevent Alzheimer's disease (AD) and other dementias. However, it is unclear to what... (Review)
Review
BACKGROUND
Engaging in late-life cognitive activity is often proposed as a strategy to delay or prevent Alzheimer's disease (AD) and other dementias. However, it is unclear to what extent the available evidence supports a causal effect of cognitive activity in dementia prevention.
METHODS
We systematically searched PubMed and EMBASE through June 2014 to identify peer-reviewed epidemiologic studies of cognitive activity and incidence of AD or all-cause dementia. Eligible articles analyzed data from cohort or nested case-control studies, explicitly defined cognitive activity, evaluated participants for AD or all-cause dementia using clearly defined criteria, and provided effect estimates adjusted for at least age and sex. We describe methodologic issues and biases relevant to interpretation of these studies, and quantify the degree of bias due to confounding and reverse causation required to nullify typically observed associations.
RESULTS
We reviewed 12 studies involving 13,939 participants and 1,663 dementia cases, of which 565 were specifically evaluated as AD. Most studies found associations between late-life cognitive activity and lower AD and/or all-cause dementia incidence. Differences in cognitive activity operationalization across studies precluded meta-analysis of effect estimates. Our bias analysis indicated that the observed inverse associations are probably robust to unmeasured confounding, and likely only partially explained by reverse causation.
CONCLUSION
Our systematic review and bias analyses provide support for the hypothesis that late-life cognitive activity offers some reduction in AD and all-cause dementia risk. However, more data are needed to confirm this relationship and on the optimal type, duration, intensity, and timing of that activity.
Topics: Alzheimer Disease; Bias; Case-Control Studies; Causality; Cognition; Cohort Studies; Confounding Factors, Epidemiologic; Dementia; Humans; Incidence; Proportional Hazards Models; Protective Factors
PubMed: 27227783
DOI: 10.1097/EDE.0000000000000513 -
PloS One 2015Metabolic factors are increasingly recognized to play an important role in the pathogenesis of Alzheimer's disease and dementia. Abnormal parathyroid hormone (PTH)... (Review)
Review
BACKGROUND
Metabolic factors are increasingly recognized to play an important role in the pathogenesis of Alzheimer's disease and dementia. Abnormal parathyroid hormone (PTH) levels play a role in neuronal calcium dysregulation, hypoperfusion and disrupted neuronal signaling. Some studies support a significant link between PTH levels and dementia whereas others do not.
METHODS
We conducted a systematic review through January 2014 to evaluate the association between PTH and parathyroid conditions, cognitive function and dementia. Eleven electronic databases and citation indexes were searched including Medline, Embase and the Cochrane Library. Hand searches of selected journals, reference lists of primary studies and reviews were also conducted along with websites of key organizations. Two reviewers independently screened titles and abstracts of identified studies. Data extraction and study quality were performed by one and checked by a second reviewer using predefined criteria. A narrative synthesis was performed due to the heterogeneity of included studies.
RESULTS
The twenty-seven studies identified were of low and moderate quality, and challenging to synthesize due to inadequate reporting. Findings from six observational studies were mixed but suggest a link between higher serum PTH levels and increased odds of poor cognition or dementia. Two case-control studies of hypoparathyroidism provide limited evidence for a link with poorer cognitive function. Thirteen pre-post surgery studies for primary hyperparathyroidism show mixed evidence for improvements in memory though limited agreement in other cognitive domains. There was some degree of cognitive impairment and improvement postoperatively in observational studies of secondary hyperparathyroidism but no evident pattern of associations with specific cognitive domains.
CONCLUSIONS
Mixed evidence offers weak support for a link between PTH, cognition and dementia due to the paucity of high quality research in this area.
Topics: Alzheimer Disease; Calcium; Cognition; Humans; Memory; Neurons; Parathyroid Hormone
PubMed: 26010883
DOI: 10.1371/journal.pone.0127574 -
Neurology Oct 2022Leisure activities are major components of modifiable and healthy lifestyles and are proposed to help prevent the development of dementia. This study aimed to assess the... (Meta-Analysis)
Meta-Analysis
BACKGROUND AND OBJECTIVES
Leisure activities are major components of modifiable and healthy lifestyles and are proposed to help prevent the development of dementia. This study aimed to assess the effects of different types of leisure activities, including cognitive, physical, and social activities, on the incidence of all-cause dementia (ACD), Alzheimer disease (AD), and vascular dementia (VD).
METHODS
We performed a systematic review and meta-analysis of the Cochrane, PubMed, Embase, and Web of Science databases to identify longitudinal studies that examined associations between leisure activities and dementia. Relative risks (RRs) and 95% CIs were pooled using random-effects meta-analysis. Subgroup analyses were used to estimate potential effect modifiers. The study was registered with PROSPERO (CRD42019116857).
RESULTS
A total of 38 longitudinal studies, with 2,154,818 participants at baseline, 74,700 ACD cases, 2,848 AD cases, and 1,423 VD cases during follow-up, were included in the meta-analysis. The subgroup analyses showed that physical (RR 0.83, 95% CI 0.78-0.88), cognitive (RR 0.77; 95% CI 0.68-0.87), and social (RR 0.93; 95% CI 0.87-0.99) activities were associated with a decreased incidence of ACD. In addition, physical (RR 0.87; 95% CI 0.78-0.96) and cognitive (RR 0.66; 95% CI 0.52-0.85) activities were related to a reduced risk of AD. Physical activity (RR 0.67; 95% CI 0.53-0.85) was associated with a lower incidence of VD.
DISCUSSION
Our findings suggest that leisure activities are inversely associated with a risk of ACD, AD, and VD.
Topics: Humans; Dementia; Risk Factors; Alzheimer Disease; Dementia, Vascular; Leisure Activities
PubMed: 35948447
DOI: 10.1212/WNL.0000000000200929 -
Cells Dec 2023The greatest risk factor for neurodegeneration is the aging of the multiple cell types of human CNS, among which microglia are important because they are the "sentinels"... (Review)
Review
The greatest risk factor for neurodegeneration is the aging of the multiple cell types of human CNS, among which microglia are important because they are the "sentinels" of internal and external perturbations and have long lifespans. We aim to emphasize microglial signatures in physiologic brain aging and Alzheimer's disease (AD). A systematic literature search of all published articles about microglial senescence in human healthy aging and AD was performed, searching for PubMed and Scopus online databases. Among 1947 articles screened, a total of 289 articles were assessed for full-text eligibility. Microglial transcriptomic, phenotypic, and neuropathological profiles were analyzed comprising healthy aging and AD. Our review highlights that studies on animal models only partially clarify what happens in humans. Human and mice microglia are hugely heterogeneous. Like a two-sided coin, microglia can be protective or harmful, depending on the context. Brain health depends upon a balance between the actions and reactions of microglia maintaining brain homeostasis in cooperation with other cell types (especially astrocytes and oligodendrocytes). During aging, accumulating oxidative stress and mitochondrial dysfunction weaken microglia leading to dystrophic/senescent, otherwise over-reactive, phenotype-enhancing neurodegenerative phenomena. Microglia are crucial for managing Aβ, pTAU, and damaged synapses, being pivotal in AD pathogenesis.
Topics: Humans; Mice; Animals; Alzheimer Disease; Microglia; Healthy Aging; Aging; Brain
PubMed: 38132144
DOI: 10.3390/cells12242824 -
Clinical Neurophysiology : Official... Dec 2022Alzheimer's disease dementia (AD) and its preclinical stage, mild cognitive impairment (MCI), are critical issues confronting the aging society. Non-invasive brain... (Meta-Analysis)
Meta-Analysis
OBJECTIVE
Alzheimer's disease dementia (AD) and its preclinical stage, mild cognitive impairment (MCI), are critical issues confronting the aging society. Non-invasive brain stimulation (NIBS) techniques have the potential to be effective tools for enhancing cognitive functioning. The main objective of our meta-analysis was to quantify and update the status of the efficacy of repetitive Transcranial Magnetic Stimulation (rTMS) and Transcranial Direct Current Stimulation (tDCS) when applied in AD and MCI.
METHODS
The systematic literature search was conducted in PubMed and Web of Science according to PRISMA statement.
RESULTS
Pooled effect sizes (Hedges' g) from 32 studies were analyzed using random effect models. We found both, rTMS and tDCS to have significant immediate cognition-enhancing effect in AD with rTMS inducing also beneficial long-term effects. We found no evidence for synergistic effect of cognitive training with NIBS.
CONCLUSIONS
In AD a clinical recommendation can be made for NEURO-AD system and for high-frequency rTMS over the left dorsolateral prefrontal cortex (DLPFC) as probably effective protocols (B-level of evidence) and for anodal tDCS over the left DLPFC as a possibly effective.
SIGNIFICANCE
According to scientific literature, NIBS may be an effective method for improving cognition in AD and possibly in MCI.
Topics: Humans; Alzheimer Disease; Brain; Cognition; Cognitive Dysfunction; Transcranial Direct Current Stimulation; Transcranial Magnetic Stimulation
PubMed: 36215904
DOI: 10.1016/j.clinph.2022.09.010