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Islet amyloid polypeptide (amylin) secreted from the pancreas crosses from the blood to the brain parenchyma and forms cerebral mixed amylin-ß amyloid (Aß) plaques in persons with Alzheimer's disease (AD). Cerebral amylin-Aß plaques are found in both sporadic and early-onset familial AD; however, the role of amylin-Aß co-aggregation in potential mechanisms underlying this association remains unknown, in part due to lack of assays for detection of these complexes. Here, we report the development of an ELISA to detect amylin-Aß hetero-oligomers in brain tissue and blood. The amylin-Aß ELISA relies on a monoclonal anti-Aß mid-domain antibody (detection) and a polyclonal anti-amylin antibody (capture) designed to recognize an epitope that is distinct from the high affinity amylin-Aß binding sites. The utility of this assay is supported by the analysis of molecular amylin-Aß codeposition in postmortem brain tissue obtained from persons with and without AD pathology. By using transgenic AD-model rats, we show that this new assay can detect circulating amylin-Aß hetero-oligomers in the blood and is sensitive to their dissociation to monomers. This is important because therapeutic strategies to block amylin-Aß co-aggregation could reduce or delay the development and progression of AD.
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Enfermedad de Alzheimer , Péptidos beta-Amiloides , Encéfalo , Animales , Ratones , Ratas , Enfermedad de Alzheimer/diagnóstico , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/tratamiento farmacológico , Péptidos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Polipéptido Amiloide de los Islotes Pancreáticos/metabolismo , Ratones Transgénicos , Páncreas/metabolismo , Ratas TransgénicasRESUMEN
Recent therapeutic advances provide heightened motivation for accurate diagnosis of the underlying biologic causes of dementia. This review focuses on the importance of clinical recognition of limbic-predominant age-related TDP-43 encephalopathy (LATE). LATE affects approximately one-quarter of older adults and produces an amnestic syndrome that is commonly mistaken for Alzheimer's disease (AD). Although AD and LATE often co-occur in the same patients, these diseases differ in the protein aggregates driving neuropathology (Aß amyloid/tau vs TDP-43). This review discusses signs and symptoms, relevant diagnostic testing, and potential treatment implications for LATE that may be helpful for physicians, patients, and families. ANN NEUROL 2023;94:211-222.
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Enfermedad de Alzheimer , Humanos , Anciano , Enfermedad de Alzheimer/patología , Proteínas tau/metabolismo , Péptidos beta-Amiloides/metabolismoRESUMEN
BACKGROUND AND PURPOSE: The immune response changes during aging and the progression of Alzheimer's disease (AD) and related dementia (ADRD). Terminally differentiated effector memory T cells (called TEMRA) are important during aging and AD due to their cytotoxic phenotype and association with cognitive decline. However, it is not clear if the changes seen in TEMRAs are specific to AD-related cognitive decline specifically or are more generally correlated with cognitive decline. This study aimed to examine whether TEMRAs are associated with cognition and plasma biomarkers of AD, neurodegeneration, and neuroinflammation in a community-based cohort of older adults. METHODS: Study participants from a University of Kentucky Alzheimer's Disease Research Center (UK-ADRC) community-based cohort of aging and dementia were used to test our hypothesis. There were 84 participants, 44 women and 40 men. Participants underwent physical examination, neurological examination, medical history, cognitive testing, and blood collection to determine plasma biomarker levels (Aß42/Aß40 ratio, total tau, Neurofilament Light chain (Nf-L), Glial Fibrillary Acidic Protein (GFAP)) and to isolate peripheral blood mononuclear cells (PBMCs). Flow cytometry was used to analyze PBMCs from study participants for effector and memory T cell populations, including CD4+ and CD8+ central memory T cells (TCM), Naïve T cells, effector memory T cells (TEM), and effector memory CD45RA+ T cells (TEMRA) immune cell markers. RESULTS: CD8+ TEMRAs were positively correlated with Nf-L and GFAP. We found no significant difference in CD8+ TEMRAs based on cognitive scores and no associations between CD8+ TEMRAs and AD-related biomarkers. CD4+ TEMRAs were associated with cognitive impairment on the MMSE. Gender was not associated with TEMRAs, but it did show an association with other T cell populations. CONCLUSION: These findings suggest that the accumulation of CD8+ TEMRAs may be a response to neuronal injury (Nf-L) and neuroinflammation (GFAP) during aging or the progression of AD and ADRD. As our findings in a community-based cohort were not clinically-defined AD participants but included all ADRDs, this suggests that TEMRAs may be associated with changes in systemic immune T cell subsets associated with the onset of pathology.
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INTRODUCTION: Protein-based plasma assays provide hope for improving accessibility and specificity of molecular diagnostics to diagnose dementia. METHODS: Plasma was obtained from participants (N = 837) in our community-based University of Kentucky Alzheimer's Disease Research Center cohort. We evaluated six Alzheimer's disease (AD)- and neurodegeneration-related (Aß40, Aß42, Aß42/40, p-tau181, total tau, and NfLight) and five inflammatory biomarkers (TNFð¼, IL6, IL8, IL10, and GFAP) using the SIMOA-based protein assay platform. Statistics were performed to assess correlations. RESULTS: Our large cohort reflects previous plasma biomarker findings. Relationships between biomarkers to understand AD-inflammatory biomarker correlations showed significant associations between AD and inflammatory biomarkers suggesting peripheral inflammatory interactions with increasing AD pathology. Biomarker associations parsed out by clinical diagnosis (normal, MCI, and dementia) reveal changes in strength of the correlations across the cognitive continuum. DISCUSSION: Unique AD-inflammatory biomarker correlations in a community-based cohort reveal a new avenue for utilizing plasma-based biomarkers in the assessment of AD and related dementias. HIGHLIGHTS: Large community cohorts studying sex, age, and APOE genotype effects on biomarkers are few. It is unknown how biomarker-biomarker associations vary through aging and dementia. Six AD (Aß40, Aß42, Aß42/40, p-tau181, total tau, and NfLight) and five inflammatory biomarkers (TNFα, IL6, IL8, IL10, and GFAP) were used to examine associations between biomarkers. Plasma biomarkers suggesting increasing cerebral AD pathology corresponded to increases in peripheral inflammatory markers, both pro-inflammatory and anti-inflammatory. Strength of correlations, between pairs of classic AD and inflammatory plasma biomarker, changes throughout cognitive progression to dementia.
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Enfermedad de Alzheimer , Disfunción Cognitiva , Humanos , Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides , Interleucina-10 , Interleucina-6 , Interleucina-8 , Proteínas tau , Biomarcadores , Reino UnidoRESUMEN
INTRODUCTION: Recent growth in the functionality and use of technology has prompted an increased interest in the potential for remote or decentralized clinical trials in dementia. There are many potential benefits associated with decentralized medication trials, but we currently lack specific recommendations for their delivery in the dementia field. METHODS: A modified Delphi method engaged an expert panel to develop recommendations for the conduct of decentralized medication trials in dementia prevention. A working group of researchers and clinicians with expertise in dementia trials further refined the recommendations. RESULTS: Overall, the recommendations support the delivery of decentralized trials in dementia prevention provided adequate safety checks and balances are included. A total of 40 recommendations are presented, spanning aspects of decentralized clinical trials, including safety, dispensing, outcome assessment, and data collection. DISCUSSION: These recommendations provide an accessible, pragmatic guide for the design and conduct of remote medication trials for dementia prevention. HIGHLIGHTS: Clinical trials of medication have begun adopting decentralized approaches. Researchers in the field lack guidance on what would be appropriate circumstances and frameworks for what would be appropriate circumstances and frameworks for the use of decentralized trial methods in dementia prevention. The present report provides consensus-based expert recommendations for decentralized clinical trials for dementia prevention.
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Ensayos Clínicos como Asunto , Consenso , Demencia , Humanos , Demencia/prevención & control , Demencia/tratamiento farmacológico , Técnica Delphi , Proyectos de Investigación/normasRESUMEN
The amygdala is vulnerable to multiple or "mixed" mis-aggregated proteins associated with neurodegenerative conditions that can manifest clinically with amnestic dementia; the amygdala region is often affected even at earliest disease stages. With the original intent of identifying novel dementia-associated proteins, the detergent-insoluble proteome was characterized from the amygdalae of 40 participants from the University of Kentucky Alzheimer's Disease Center autopsy cohort. These individuals encompassed a spectrum of clinical conditions (cognitively normal to severe amnestic dementia). Polypeptides from the detergent-insoluble fraction were interrogated using liquid chromatography-electrospray ionization-tandem mass spectrometry. As anticipated, portions of peptides previously associated with neurologic diseases were enriched from subjects with dementia. Among all detected peptides, Apolipoprotein E (ApoE) stood out: even more than the expected Tau, APP/Aß, and α-Synuclein peptides, ApoE peptides were strongly enriched in dementia cases, including from individuals lacking the APOE ε4 genotype. The amount of ApoE protein detected in detergent-insoluble fractions was robustly associated with levels of complement proteins C3 and C4. Immunohistochemical staining of APOE ε3/ε3 subjects' amygdalae confirmed ApoE co-localization with C4 in amyloid plaques. Thus, analyses of human amygdala proteomics indicate that rather than being only an "upstream" genetic risk factor, ApoE is an aberrantly aggregated protein in its own right, and show that the ApoE protein may play active disease-driving mechanistic roles in persons lacking the APOE ε4 allele.
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Enfermedad de Alzheimer , Apolipoproteínas E , Demencia , Alelos , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides/metabolismo , Apolipoproteína E4/genética , Apolipoproteínas E/metabolismo , Biomarcadores/metabolismo , Demencia/genética , Demencia/metabolismo , Demencia/patología , Detergentes , Genotipo , HumanosRESUMEN
BACKGROUND: Polypharmacy and inappropriate medications may be a modifiable risk factor for Alzheimer's Disease and Related Dementias (ADRD). Medication therapy management (MTM) interventions may mitigate medication-induced cognitive dysfunction and delay onset of symptomatic impairment. The objective of the current study is to describe an MTM protocol for a patient-centered team intervention (pharmacist and non-pharmacist clinician) in a randomized controlled trial (RCT) directed at delaying the symptomatic onset of ADRD. METHODS: Community dwelling adults 65 + years, non-demented, using ≥ 1 potentially inappropriate medications (PIM) were enrolled in an RCT to evaluate the effect of an MTM intervention on improving medication appropriateness and cognition (NCT02849639). The MTM intervention involved a three-step process: (1) pharmacist identified potential medication-related problems (MRPs) and made initial recommendations for prescribed and over-the-counter medications, vitamins, and supplements; (2) study team reviewed all initial recommendations together with the participants, allowing for revisions prior to the finalized recommendations; (3) participant responses to final recommendations were recorded. Here, we describe initial recommendations, changes during team engagement, and participant responses to final recommendations. RESULTS: Among the 90 participants, a mean 6.7 ± 3.6 MRPs per participant were reported. Of the 259 initial MTM recommendations made for the treatment group participants (N = 46), 40% percent underwent revisions in the second step. Participants reported willingness to adopt 46% of final recommendations and expressed need for additional primary care input in response to 38% of final recommendations. Willingness to adopt final recommendations was highest when therapeutic switches were offered and/or with anticholinergic medications. CONCLUSION: The evaluation of modifications to MTM recommendations demonstrated that pharmacists' initial MTM recommendations often changed following the participation in the multidisciplinary decision-making process that incorporated patient preferences. The team was encouraged to see a correlation between engaging patients and a positive overall response towards participant acceptance of final MTM recommendations. TRIAL REGISTRATION: Study registration number: clinicaltrial.gov NCT02849639 registered on 29/07/2016.
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Enfermedad de Alzheimer , Administración del Tratamiento Farmacológico , Humanos , Atención Dirigida al Paciente , Lista de Medicamentos Potencialmente InapropiadosRESUMEN
INTRODUCTION: This study examined the relationships between 13 novel blood-plasma biomarkers and dementia-related demographic and health factors in a cohort of 237 cognitively normal research volunteers whose average age was ≈82 years and who were 63% female. METHODS: We regressed each biomarker on selected covariates to explore the associations between the biomarkers and selected factors to assess whether they may contribute to biomarker values. Post hoc sensitivity analyses were done with updated data and consistent variable sets for robustness and batch effects. RESULTS: Biomarker concentrations were largely not associated with demographics or health conditions, but some expected associations (e.g., apolipoprotein E [APOE] status with amyloid beta [Aß]42/Aß40) were observed. Post hoc results remained similar to those of the main analysis. DISCUSSION: The absence of strong associations between the biomarkers with age, gender, or medical conditions suggests that changes in these biomarkers, when observed, may be attributable to neuropathological changes. HIGHLIGHTS: Among N = 237 cognitively normal adults, we studied candidate Alzheimer's disease and related dementia (ADRD) plasma biomarkers. Biomarkers were largely not associated with demographic or health factors. Apolipoprotein E (APOE) status was associated with amyloid beta (Aß)42/Aß40 ratio. These results support hypotheses that plasma biomarkers are informative for ADRD.
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Enfermedad de Alzheimer , Péptidos beta-Amiloides , Adulto , Humanos , Femenino , Anciano de 80 o más Años , Masculino , Voluntarios Sanos , Enfermedad de Alzheimer/diagnóstico , Apolipoproteínas E/genética , BiomarcadoresRESUMEN
INTRODUCTION: Clinically, detection of disease-causing pathology associated with Alzheimer's disease (AD) and vascular contributions to cognitive impairment and dementia (VCID) is limited to magnetic resonance imaging and positron emission tomography scans, which are expensive and not widely accessible. Here, we assess angiogenic, inflammatory, and AD-related plasma biomarkers to determine their relationships with human post mortem neuropathology. METHOD: Plasma samples were analyzed using a digital immunoassay and pathological evaluation was performed by University of Kentucky Alzheimer's Disease Research Center neuropathologists. The association of plasma markers with neuropathology was estimated via proportional odds and logistic regressions adjusted for age. RESULTS: Included cases (N = 90) showed increased tau/amyloid beta (Aß)42 ratio, glial fibrillary acidic protein (GFAP), vascular endothelial growth factor A (VEGF-A), and placental growth factor (PlGF) were positively associated with higher level of AD neuropathological change, while higher Aß42/Aß40 ratio was inversely associated. Higher PlGF, VEGF-A, and interleukin 6 were inversely associated with chronic cerebrovascular disease, while Aß42/Aß40 ratio was positively associated. DISCUSSION: Our results provide support for the continued study of plasma biomarkers as a clinical screening tool for AD and VCID pathology.
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Enfermedad de Alzheimer , Disfunción Cognitiva , Demencia Vascular , Humanos , Femenino , Enfermedad de Alzheimer/patología , Factor A de Crecimiento Endotelial Vascular , Péptidos beta-Amiloides , Neuropatología , Autopsia , Factor de Crecimiento Placentario , Biomarcadores , Proteínas tauRESUMEN
IMPORTANCE: Supporting community residency of adults with Alzheimer's disease (AD) is a critical public health initiative. Occupational therapy can contribute to this goal. OBJECTIVE: To assess the feasibility of a novel telehealth intervention to support occupational engagement in community-residing people with AD. DESIGN: Single-blind, three-arm, parallel, randomized controlled trial. SETTING: Occupational therapy delivered through telehealth in participants' homes. PARTICIPANTS: People with AD who reside in the community with behavioral symptoms and their care partners (dyads). INTERVENTIONS: (1) HARMONY (Helping older Adults cReate & Manage OccupatioNs successfully), a telehealth intervention that applies principles of individualized guided discovery with environmental cueing for caregivers of persons with AD to promote activity participation and manage behavioral symptoms; (2) standardized training regarding the use of a sensory-based approach in dementia care; and (3) a control, including home safety education and weekly monitoring of behaviors. OUTCOMES AND MEASURES: Feasibility was assessed as the primary outcome measured by completion of at least 75% of the telehealth sessions. Secondary outcomes included change in functional activity performance and neuropsychiatric behavioral symptoms. RESULTS: Twenty-eight dyads participated. The intervention was feasible, with high adherence to weekly visits (M number of visits = 5.4 for HARMONY, 4.9 for standardized training, and 4.6 for control), with high participant retention in the intervention arms. HARMONY demonstrated promise in improving patient performance and behavioral symptoms. CONCLUSIONS AND RELEVANCE: HARMONY is feasibly delivered through telehealth service and has a positive effect on occupational performance and behavioral symptoms of AD. Additional studies are needed to explore effectiveness in a broader population. What This Article Adds: Use of HARMONY for community-residing adults with AD is feasible and has promise for improving functional activity performance and behavioral symptoms, as well as caregiver satisfaction.
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Enfermedad de Alzheimer , Terapia Ocupacional , Telemedicina , Humanos , Anciano , Estudios de Factibilidad , Método Simple Ciego , Síntomas ConductualesRESUMEN
PURPOSE OF THE RESEARCH: The geriatric population is the fastest-growing population in the United States and the impact of incident epilepsy on the cognitively intact geriatric population is not well-studied. Understanding how epilepsy affects the elderly is important to improve the quality of treatment and care for our aging population. This study sought to address the impact of incident epilepsy on the perceived Quality of Life (QOL) in cognitively intact elderly using the SF-36 questionnaire. METHODS: Nine hundred and twenty-seven participants were assessed from a community-based cohort. Based on a history of subsequent development of new-onset seizures, participants were divided into two groups, an incident seizure group that developed new-onset seizures after 65â¯years of age and the control group without incident seizures. Of this, six hundred eleven were analyzed with the SF-36 questionnaire after excluding for cognitive decline and inconsistent medical data. PRINCIPAL RESULTS: Statistically significant differences were found in 9 items on SF-36, involving perception of increased physical disability (pâ¯<â¯0.01; t-test), frailty (pâ¯<â¯0.04; t-test), emotional health limitations (pâ¯<â¯0.03; t-test), anxiety and sadness (pâ¯<â¯0.04; t-test), problems interfering with social activities (pâ¯<â¯0.0001; t-test). No between-group differences were found for demographic variables including age, education, gender, or minority status. Among the 611 subjects who remained cognitively normal across all longitudinal visits, 12 reported a history of new-onset seizures. Ten of these 12 subjects were seizure free as a result of treatment, with only 2 experiencing recent seizures. The incidence of seizures in our population was 300 per 100,000 person years. MAJOR CONCLUSIONS: This study identified the elderly population with incident epilepsy as a subgroup with an unmet health need, and healthcare professionals should address the potential impact of seizures with their geriatric patients to ensure comprehensive care.
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Cognición , Epilepsia , Calidad de Vida , Convulsiones , Anciano , Estudios de Casos y Controles , Cognición/fisiología , Estudios de Cohortes , Epilepsia/epidemiología , Epilepsia/psicología , Humanos , Incidencia , Calidad de Vida/psicología , Convulsiones/epidemiología , Convulsiones/prevención & control , Encuestas y CuestionariosRESUMEN
BACKGROUND: Similarities exist in behavioral expression of autism spectrum disorder (ASD) and Alzheimer's disease and related dementias (ADRD). The purpose of this study was to assess presence of behavioral and psychiatric symptoms of dementia (BPSD) and ASD-like behaviors in adults with ADRD. METHODS: Using a cross-sectional design, data from University of Kentucky Alzheimer's Disease Center participant cohort were used. Hierarchical linear regression was used to assess (1) the relationship between ASD-like behaviors (measured by the Gilliam Autism Rating Scale-Second Edition, GARS-2) and BPSD measured by the Neuropsychiatric Inventory (NPI), and (2) the relationship between ASD-like behaviors and dementia severity (measured by the Clinical Dementia Rating [CDR] sum of boxes), when controlling for BPSD. RESULTS: Complete data were available for 142 participants. Using α of 0.05, analyses identified ASD behaviors were significantly associated with BPSD severity ratings (r = 0.47; p < 0.001) and dementia severity (r = 0.46; p < 0.001). GARS-2 explained 6.1% (p < 0.001) of variance in CDR sum of boxes when controlling for NPI and other covariates. DISCUSSION: There is significant overlap in behaviors characteristic of ASD and BPSD as assessed by the NPI and GARS-2, despite the use of these instruments in disparate developmental vs. aging settings. ASD behaviors appear to not be solely present in early childhood as a manifestation of ASD but are also present in older adults with neurodegenerative cognitive impairment. Such associations warrant additional research into causation, assessment, and behavioral interventions to further enable new therapeutic approaches targeting ASD behaviors across the lifespan.
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Enfermedad de Alzheimer , Trastorno del Espectro Autista , Demencia , Anciano , Enfermedad de Alzheimer/psicología , Trastorno del Espectro Autista/complicaciones , Trastorno del Espectro Autista/epidemiología , Síntomas Conductuales , Preescolar , Estudios Transversales , Demencia/psicología , Humanos , Escalas de Valoración PsiquiátricaRESUMEN
There is an urgent need for interventions that can prevent or delay cognitive decline and dementia. Decades of epidemiological research have identified potential pharmacological strategies for risk factor modification to prevent these serious conditions, but clinical trials have failed to confirm the potential efficacy for such interventions. Our multidisciplinary international group reviewed seven high-potential intervention strategies in an attempt to identify potential reasons for the mismatch between the observational and trial results. In considering our findings, we offer constructive recommendations for the next steps. Overall, we observed some differences in the observational evidence base for the seven strategies, but several common methodological themes that emerged. These themes included the appropriateness of trial populations and intervention strategies, including the timing of interventions and other aspects of trials methodology. To inform the design of future clinical trials, we provide recommendations for the next steps in finding strategies for effective dementia risk reduction.
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Disfunción Cognitiva , Demencia , Demencia/epidemiología , Demencia/prevención & control , Humanos , Motivación , Factores de Riesgo , Conducta de Reducción del RiesgoRESUMEN
Brain arteriolosclerosis (B-ASC), characterized by pathologic arteriolar wall thickening, is a common finding at autopsy in aged persons and is associated with cognitive impairment. Hypertension and diabetes are widely recognized as risk factors for B-ASC. Recent research indicates other and more complex risk factors and pathogenetic mechanisms. Here, we describe aspects of the unique architecture of brain arterioles, histomorphologic features of B-ASC, relevant neuroimaging findings, epidemiology and association with aging, established genetic risk factors, and the co-occurrence of B-ASC with other neuropathologic conditions such as Alzheimer's disease and limbic-predominant age-related TDP-43 encephalopathy (LATE). There may also be complex physiologic interactions between metabolic syndrome (e.g., hypertension and inflammation) and brain arteriolar pathology. Although there is no universally applied diagnostic methodology, several classification schemes and neuroimaging techniques are used to diagnose and categorize cerebral small vessel disease pathologies that include B-ASC, microinfarcts, microbleeds, lacunar infarcts, and cerebral amyloid angiopathy (CAA). In clinical-pathologic studies that factored in comorbid diseases, B-ASC was independently associated with impairments of global cognition, episodic memory, working memory, and perceptual speed, and has been linked to autonomic dysfunction and motor symptoms including parkinsonism. We conclude by discussing critical knowledge gaps related to B-ASC and suggest that there are probably subcategories of B-ASC that differ in pathogenesis. Observed in over 80% of autopsied individuals beyond 80 years of age, B-ASC is a complex and under-studied contributor to neurologic disability.
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Encéfalo/patología , Arteriosclerosis Intracraneal/patología , Anciano , Anciano de 80 o más Años , Animales , Arteriolas/patología , Angiopatía Amiloide Cerebral , Trastornos del Conocimiento/etiología , Trastornos del Conocimiento/patología , Trastornos del Conocimiento/psicología , Humanos , Arteriosclerosis Intracraneal/psicología , NeuroimagenRESUMEN
Small cerebral vascular disease (SCeVD) demonstrated by white matter hyperintensity (WMH) on MRI contributes to the development of dementia in Alzheimer's disease (AD), but it has not been possible to correlate onset, severity, or protein components of SCeVD with characteristics of WMH in living patients. Plasma endothelial-derived exosomes (EDEs) were enriched by two-step immunoabsorption from four groups of participants with no clinical evidence of cerebrovascular disease: cognitively normal (CN) without WMH (CN without SCeVD, n = 20), CN with SCeVD (n = 22), preclinical AD (pAD) + mild cognitive impairment (MCI) without SCeVD (pAD/MCI without SCeVD, n = 22), and pAD/MCI with SCeVD (n = 16) for ELISA quantification of cargo proteins. Exosome marker CD81-normalized EDE levels of the cerebrovascular-selective biomarkers large neutral amino acid transporter 1 (LAT-1), glucose transporter type 1 (Glut-1), and permeability-glycoprotein (p-GP, ABCB1) were similarly significantly higher in the CN with SCeVD and pAD/MCI with SCeVD groups than their corresponding control groups without SCeVD. CD81-normalized EDE levels of Aß40 and Aß42 were significantly higher in the pAD/MCI with SCeVD group but not in the CN with SCeVD group relative to controls without SCeVD. Levels of normal cellular prion protein (PrPc), a receptor for amyloid peptides, and phospho-181T-tau were higher in both CN and pAD/MCI with SCeVD groups than in the corresponding controls. High EDE levels of Aß40, Aß42, and phospho-181T-tau in patients with WMH suggesting SCeVD appear at the pre-clinical or MCI stage of AD and therapeutic lowering of neurotoxic peptide levels may delay progression of AD angiopathy.
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Enfermedad de Alzheimer/diagnóstico , Biomarcadores/sangre , Enfermedades de los Pequeños Vasos Cerebrales/diagnóstico , Disfunción Cognitiva/diagnóstico , Células Endoteliales/metabolismo , Exosomas/metabolismo , Sustancia Blanca/patología , Anciano , Enfermedad de Alzheimer/sangre , Péptidos beta-Amiloides/sangre , Estudios de Casos y Controles , Enfermedades de los Pequeños Vasos Cerebrales/sangre , Disfunción Cognitiva/sangre , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Estudios Prospectivos , Sustancia Blanca/metabolismo , Proteínas tau/sangreRESUMEN
Finite Markov chains are useful tools for studying transitions among health states; these chains can be complex consisting of a mix of transient and absorbing states. The transition probabilities, which are often affected by covariates, can be difficult to estimate due to the presence of many covariates and/or a subset of transitions that are rarely observed. The purpose of this article is to show how to estimate the effect of a subset of covariates of interest after adjusting for the presence of multiple other covariates by applying multidimensional dimension reduction to the latter. The case in which transitions within each row of the one-step transition probability matrix are estimated by multinomial logistic regression is discussed in detail. Dimension reduction for the adjustment covariates involves estimating the effect of the covariates by a product of matrices iteratively; at each iteration one matrix in the product is fixed while the second is estimated using either standard software or nonlinear estimation, depending on which of the matrices in the product is fixed. The algorithm is illustrated by an application where the effect of at least one Apolipoprotein-E (APOE) gene ϵ4 allele on transition probability is estimated in a Markov Chain that includes adjustment for eight covariates and focuses on transitions from normal cognition to several forms of mild cognitive impairment, with possible absorption into dementia. Data were drawn from annual cognitive assessments of 649 participants enrolled in the BRAiNS cohort at the University of Kentucky's Alzheimer's Disease Research Center.
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Disfunción Cognitiva , Cognición , Estudios de Cohortes , Humanos , Modelos Logísticos , Cadenas de MarkovRESUMEN
BACKGROUND: Alzheimer disease (AD) research increasingly requires healthy individuals willing to undergo genetic testing. OBJECTIVE: This study seeks to: (1) describe older adults' beliefs about AD genetic testing, worry about AD, and fear of AD stigma, and (2) explore how these constructs relate to research participation. METHODS: Surveys were sent to participants active in AD-observational research and those that were not. Three measures of research participation were explored: (1) being a current research participant, (2) self-report of clinical trial participation, and (3) expressing genetic registry interest. RESULTS: The majority of the 502 respondents perceived greater benefit than the risk associated with AD genetic testing. AD worry and perceptions of AD stigma were low. Higher levels of AD worry and lower perceptions of AD stigma were associated with being a current AD research volunteer. AD worry and stigma were unrelated to clinical trial participation or genetic registry interest; these research participation measures were associated with AD genetic testing benefit. CONCLUSIONS: Beliefs about AD genetic testing, AD worry, and AD stigma are related to research participation, but relationships vary based on the research participation investigated. Future work should identify how these findings can inform outreach and recruitment efforts.
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Enfermedad de Alzheimer/genética , Ansiedad , Miedo , Pruebas Genéticas , Selección de Paciente , Estigma Social , Anciano , Femenino , Humanos , Masculino , Encuestas y CuestionariosRESUMEN
BACKGROUND: Registries have been proposed as a novel way to accelerate targeted recruitment for Alzheimer disease prevention clinical trials. However, there are limited data regarding registry effectiveness at accelerating recruitment and enrollment in research opportunities. This manuscript explores one site's experience with GeneMatch, a novel genetic registry for Alzheimer disease research. METHODS: Referrals from GeneMatch to the site were tracked to understand the demographics of those referred and ultimate research enrollment outcomes. Referrals were cross-referenced with the site's existing recruitment database, to better understand the role of GeneMatch in the context of existing recruitment efforts. RESULTS: GeneMatch referred 86 individuals to the site, resulting in 54 individuals coming into the site to pursue research involvement further. The majority of referrals (52/86, 60.47%) did not have prior contact with the site about research engagement, and having prior site contact did not significantly relate to engaging in on-site research. CONCLUSIONS: GeneMatch helped identify new individuals for participation in Alzheimer disease prevention studies. Results highlight the value of continuing local site-level efforts while also taking advantage of registries to enhance research recruitment. Ongoing efforts to further develop these and other novel strategies for outreach and engagement are much needed.
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Enfermedad de Alzheimer/genética , Investigación Biomédica , Pruebas Genéticas , Selección de Paciente , Sistema de Registros , Anciano , Femenino , Humanos , Masculino , Derivación y ConsultaRESUMEN
TAR-DNA binding protein-43 (TDP-43) proteinopathy is seen in multiple brain diseases. A standardized terminology was recommended recently for common age-related TDP-43 proteinopathy: limbic-predominant, age-related TDP-43 encephalopathy (LATE) and the underlying neuropathological changes, LATE-NC. LATE-NC may be co-morbid with Alzheimer's disease neuropathological changes (ADNC). However, there currently are ill-defined diagnostic classification issues among LATE-NC, ADNC, and frontotemporal lobar degeneration with TDP-43 (FTLD-TDP). A practical challenge is that different autopsy cohorts are composed of disparate groups of research volunteers: hospital- and clinic-based cohorts are enriched for FTLD-TDP cases, whereas community-based cohorts have more LATE-NC cases. Neuropathological methods also differ across laboratories. Here, we combined both cases and neuropathologists' diagnoses from two research centres-University of Pennsylvania and University of Kentucky. The study was designed to compare neuropathological findings between FTLD-TDP and pathologically severe LATE-NC. First, cases were selected from the University of Pennsylvania with pathological diagnoses of either FTLD-TDP (n = 33) or severe LATE-NC (mostly stage 3) with co-morbid ADNC (n = 30). Sections from these University of Pennsylvania cases were cut from amygdala, anterior cingulate, superior/mid-temporal, and middle frontal gyrus. These sections were stained for phospho-TDP-43 immunohistochemically and evaluated independently by two University of Kentucky neuropathologists blinded to case data. A simple set of criteria hypothesized to differentiate FTLD-TDP from LATE-NC was generated based on density of TDP-43 immunoreactive neuronal cytoplasmic inclusions in the neocortical regions. Criteria-based sensitivity and specificity of differentiating severe LATE-NC from FTLD-TDP cases with blind evaluation was â¼90%. Another proposed neuropathological feature related to TDP-43 proteinopathy in aged individuals is 'Alpha' versus 'Beta' in amygdala. Alpha and Beta status was diagnosed by neuropathologists from both universities (n = 5 raters). There was poor inter-rater reliability of Alpha/Beta classification (mean κ = 0.31). We next tested a separate cohort of cases from University of Kentucky with either FTLD-TDP (n = 8) or with relatively 'pure' severe LATE-NC (lacking intermediate or severe ADNC; n = 14). The simple criteria were applied by neuropathologists blinded to the prior diagnoses at University of Pennsylvania. Again, the criteria for differentiating LATE-NC from FTLD-TDP was effective, with sensitivity and specificity â¼90%. If more representative cases from each cohort (including less severe TDP-43 proteinopathy) had been included, the overall accuracy for identifying LATE-NC was estimated at >98% for both cohorts. Also across both cohorts, cases with FTLD-TDP died younger than those with LATE-NC (P < 0.0001). We conclude that in most cases, severe LATE-NC and FTLD-TDP can be differentiated by applying simple neuropathological criteria.
Asunto(s)
Degeneración Lobar Frontotemporal/diagnóstico por imagen , Sistema Límbico/diagnóstico por imagen , Proteinopatías TDP-43/diagnóstico por imagen , Factores de Edad , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , Femenino , Degeneración Lobar Frontotemporal/fisiopatología , Humanos , Sistema Límbico/fisiopatología , Masculino , Persona de Mediana Edad , Proteinopatías TDP-43/fisiopatologíaRESUMEN
INTRODUCTION: We tested if water exchange across the blood-brain barrier (BBB), estimated with a noninvasive magnetic resonance imaging (MRI) technique, is associated with cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) and neuropsychological function. METHODS: Forty cognitively normal older adults (67-86 years old) were scanned with diffusion-prepared, arterial spin labeling (DP-ASL), which estimates water exchange rate across the BBB (kw ). Participants also underwent CSF draw and neuropsychological testing. Multiple linear regression models were run with kw as a predictor of CSF concentrations and neuropsychological scores. RESULTS: In multiple brain regions, BBB kw was positively associated with CSF amyloid beta (Aß)42 concentration levels. BBB kw was only moderately associated with neuropsychological performance. DISCUSSION: Our results suggest that low water exchange rate across the BBB is associated with low CSF Aß42 concentration. These findings suggest that kw may be a promising noninvasive indicator of BBB Aß clearance functions, a possibility which should be further tested in future research.