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1.
J Am Soc Mass Spectrom ; 34(6): 1105-1116, 2023 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-37163770

RESUMO

Proteomics research has been transformed due to high-throughput liquid chromatography (LC-MS/MS) tandem mass spectrometry instruments combined with highly sophisticated automated sample preparation and multiplexing workflows. However, scaling proteomics experiments to large sample cohorts (hundreds to thousands) requires thoughtful quality control (QC) protocols. Robust QC protocols can help with reproducibility, quantitative accuracy, and provide opportunities for more decisive troubleshooting. Our laboratory conducted a plasma proteomics study of a cohort of N = 335 patient samples using tandem mass tag (TMTpro) 16-plex batches. Over the course of a 10-month data acquisition period for this cohort we collected 271 pooled QC LC-MS/MS result files obtained from MS/MS analysis of a patient-derived pooled plasma sample, representative of the entire cohort population. This sample was tagged with TMTzero or TMTpro reagents and used to inform the daily performance of the LC-MS/MS instruments and to allow within and across sample batch normalization. Analytical variability of a number of instrumental and data analysis metrics including protein and peptide identifications, peptide spectral matches (PSMs), number of obtained MS/MS spectra, average peptide abundance, percent of peptides with a Δ m/z between ±0.003 Da, percent of MS/MS spectra obtained at the maximum injection time, and the retention time of selected tracking peptides were evaluated to help inform the design of a robust LC-MS/MS QC workflow for use in future cohort studies. This study also led to general tips for using selected metrics to inform real-time troubleshooting of LC-MS/MS performance issues with daily QC checks.


Assuntos
Proteômica , Espectrometria de Massas em Tandem , Humanos , Espectrometria de Massas em Tandem/métodos , Proteômica/métodos , Cromatografia Líquida/métodos , Reprodutibilidade dos Testes , Peptídeos/química , Controle de Qualidade
2.
Neurobiol Aging ; 124: 11-17, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36680854

RESUMO

The vascular endothelial growth factor (VEGF) family of genes has been implicated in the clinical development of Alzheimer's Disease (AD). A previous study identified associations between gene expression of VEGF family members in the prefrontal cortex and cognitive performance and AD pathology. This study explored if those associations were also observed in the blood. Consistent with previous observations in brain tissue, higher blood gene expression of placental growth factor (PGF) was associated with a faster rate of memory decline (p=0.04). Higher protein abundance of FMS-related receptor tyrosine kinase 4 (FLT4) in blood was associated with biomarker levels indicative of lower amyloid and tau pathology, opposite the direction observed in brain. Also, higher gene expression of VEGFB in blood was associated with better baseline memory (p=0.008). Notably, we observed that higher gene expression of VEGFB in blood was associated with lower expression of VEGFB in the brain (r=-0.19, p=0.02). Together, these results suggest that the VEGFB, FLT4, and PGF alterations in the AD brain may be detectable in the blood compartment.


Assuntos
Doença de Alzheimer , Disfunção Cognitiva , Humanos , Feminino , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismo , Fator de Crescimento Placentário/genética , Fatores de Crescimento do Endotélio Vascular , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Biomarcadores , Cognição , Peptídeos beta-Amiloides , Proteínas tau/genética
3.
Stroke ; 53(3): 808-816, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34702069

RESUMO

BACKGROUND AND PURPOSE: Left ventricular (LV) mass index is a marker of subclinical LV remodeling that relates to white matter damage in aging, but molecular pathways underlying this association are unknown. This study assessed if LV mass index related to cerebrospinal fluid (CSF) biomarkers of microglial activation (sTREM2 [soluble triggering receptor expressed on myeloid cells 2]), axonal injury (NFL [neurofilament light]), neurodegeneration (total-tau), and amyloid-ß, and whether these biomarkers partially accounted for associations between increased LV mass index and white matter damage. We hypothesized higher LV mass index would relate to greater CSF biomarker levels, and these pathologies would partially mediate associations with cerebral white matter microstructure. METHODS: Vanderbilt Memory and Aging Project participants who underwent cardiac magnetic resonance, lumbar puncture, and diffusion tensor imaging (n=142, 72±6 years, 37% mild cognitive impairment [MCI], 32% APOE-ε4 positive, LV mass index 51.4±8.1 g/m2, NFL 1070±588 pg/mL) were included. Linear regressions and voxel-wise analyses related LV mass index to each biomarker and diffusion tensor imaging metrics, respectively. Follow-up models assessed interactions with MCI and APOE-ε4. In models where LV mass index significantly related to a biomarker and white matter microstructure, we assessed if the biomarker mediated white matter associations. RESULTS: Among all participants, LV mass index was unrelated to CSF biomarkers (P>0.33). LV mass index interacted with MCI (P=0.01), such that higher LV mass index related to increased NFL among MCI participants. Associations were also present among APOE-ε4 carriers (P=0.02). NFL partially mediated up to 13% of the effect of increased LV mass index on white matter damage. CONCLUSIONS: Subclinical cardiovascular remodeling, measured as an increase in LV mass index, is associated with neuroaxonal degeneration among individuals with MCI and APOE-ε4. Neuroaxonal degeneration partially reflects associations between higher LV mass index and white matter damage. Findings highlight neuroaxonal degeneration, rather than amyloidosis or microglia, may be more relevant in pathways between structural cardiovascular remodeling and white matter damage.


Assuntos
Peptídeos beta-Amiloides/líquido cefalorraquidiano , Apolipoproteínas E/líquido cefalorraquidiano , Lesão Axonal Difusa/líquido cefalorraquidiano , Glicoproteínas de Membrana/líquido cefalorraquidiano , Remodelação Ventricular , Substância Branca/lesões , Proteínas tau/líquido cefalorraquidiano , Idoso , Feminino , Humanos , Masculino , Receptores Imunológicos
4.
Neuroimage Clin ; 32: 102794, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34479171

RESUMO

Subjective cognitive decline (SCD) is a perceived cognitive change prior to objective cognitive deficits, and although it is associated with Alzheimer's disease (AD) pathology, it likely results from multiple underlying pathologies. We investigated the association of white matter microstructure to SCD as a sensitive and early marker of cognitive decline and quantified the contribution of white matter microstructure separate from amyloidosis. Vanderbilt Memory & Aging Project participants with diffusion MRI data and a 45-item measure of SCD were included [n = 236, 137 cognitively unimpaired (CU), 99 with mild cognitive impairment (MCI), 73 ± 7 years, 37% female]. A subset of participants (64 CU, 40 MCI) underwent a fasting lumbar puncture for quantification of cerebrospinal fluid (CSF) amyloid-ß(CSF Aß42), total tau (CSF t-tau), and phosphorylated tau (CSF p-tau). Diffusion MRI data was post-processed using the free-water (FW) elimination technique, which allowed quantification of extracellular (FW) and intracellular compartment (fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity) microstructure. Microstructural values were quantified within 11 cognitive-related white matter tracts, including medial temporal lobe, frontal transcallosal, and fronto-parietal tracts using a region of interest approach. General linear modeling related each tract to SCD scores adjusting for age, sex, race/ethnicity, education, Framingham Stroke Risk Profile scores, APOE ε4 carrier status, diagnosis, Geriatric Depression Scale scores, hippocampal volume, and total white matter volume. Competitive models were analyzed to determine if white matter microstructural values have a unique role in SCD scores separate from CSF Aß42. FW-corrected radial diffusivity (RDT) was related to SCD scores in 8 tracts: cingulum bundle, inferior longitudinal fasciculus, as well as inferior frontal gyrus (IFG) pars opercularis, IFG orbitalis, IFG pars triangularis, tapetum, medial frontal gyrus, and middle frontal gyrus transcallosal tracts. While CSF Aß42 was related to SCD scores in our cohort (Radj2 = 39.03%; ß = -0.231; p = 0.020), competitive models revealed that fornix and IFG pars triangularis transcallosal tract RDT contributed unique variance to SCD scores beyond CSF Aß42 (Radj2 = 44.35% and Radj2 = 43.09%, respectively), with several other tract measures demonstrating nominal significance. All tracts which demonstrated nominal significance (in addition to covariates) were input into a backwards stepwise regression analysis. ILF RDT, fornix RDT, and UF FW were best associated with SCD scores (Radj2 = 46.69%; p = 6.37 × 10-12). Ultimately, we found that medial temporal lobe and frontal transcallosal tract microstructure is an important driver of SCD scores independent of early amyloid deposition. Our results highlight the potential importance of abnormal white matter diffusivity as an early contributor to cognitive decline. These results also highlight the value of incorporating multiple biomarkers to help disentangle the mechanistic heterogeneity of SCD as an early stage of cognitive decline.


Assuntos
Doença de Alzheimer , Disfunção Cognitiva , Substância Branca , Idoso , Peptídeos beta-Amiloides/metabolismo , Disfunção Cognitiva/diagnóstico por imagem , Feminino , Hipocampo/metabolismo , Humanos , Masculino , Substância Branca/diagnóstico por imagem , Substância Branca/metabolismo
5.
Neurology ; 97(4): e329-e340, 2021 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-34031194

RESUMO

OBJECTIVES: To test the hypothesis that increased aortic stiffening is associated with greater CSF evidence of core Alzheimer disease pathology (ß-amyloid [Aß], phosphorylated tau [p-tau]), neurodegeneration (total tau [t-tau]), synaptic dysfunction (neurogranin), neuroaxonal injury (neurofilament light [NFL]), and neuroinflammation (YKL-40, soluble triggering receptor expressed on myeloid cells 2 [sTREM2]), we analyzed pulse wave velocity (PWV) data and CSF data among older adults. METHODS: Participants free of stroke and dementia from the Vanderbilt Memory and Aging Project, an observational community-based study, underwent cardiac magnetic resonance to assess aortic PWV (meters per second) and lumbar puncture to obtain CSF. Linear regressions related aortic PWV to CSF Aß, p-tau, t-tau, neurogranin, NFL, YKL-40, and sTREM2 concentrations after adjustment for age, race/ethnicity, education, apolipoprotein (APOE) ε4 status, Framingham Stroke Risk Profile, and cognitive diagnosis. Models were repeated testing PWV interactions with age, diagnosis, APOE ε4, and hypertension on each biomarker. RESULTS: One hundred forty-six participants were examined (age 72 ± 6 years). Aortic PWV interacted with age on p-tau (ß = 0.31, p = 0.04), t-tau, (ß = 2.67, p = 0.05), neurogranin (ß = 0.94, p = 0.04), and sTREM2 (ß = 20.4, p = 0.05). Among participants >73 years of age, higher aortic PWV related to higher p-tau (ß = 2.4, p = 0.03), t-tau (ß = 19.3, p = 0.05), neurogranin (ß = 8.4, p = 0.01), and YKL-40 concentrations (ß = 7,880, p = 0.005). Aortic PWV had modest interactions with diagnosis on neurogranin (ß = -10.76, p = 0.03) and hypertension status on YKL-40 (ß = 18,020, p < 0.001). CONCLUSIONS: Among our oldest participants, ≥74 years of age, greater aortic stiffening is associated with in vivo biomarker evidence of neuroinflammation, tau phosphorylation, synaptic dysfunction, and neurodegeneration, but not amyloidosis. Central arterial stiffening may lead to cumulative cerebral microcirculatory damage and reduced blood flow delivery to tissue, resulting in neuroinflammation and neurodegeneration in more advanced age.


Assuntos
Envelhecimento/fisiologia , Coração/diagnóstico por imagem , Inflamação/diagnóstico por imagem , Doenças Neurodegenerativas/diagnóstico por imagem , Rigidez Vascular/fisiologia , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/líquido cefalorraquidiano , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Biomarcadores/líquido cefalorraquidiano , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Neurodegenerativas/líquido cefalorraquidiano , Fosforilação , Análise de Onda de Pulso , Proteínas tau/líquido cefalorraquidiano
6.
Front Aging Neurosci ; 12: 139, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32581762

RESUMO

INTRODUCTION: While Alzheimer's disease (AD) is divided into severity stages, mild cognitive impairment (MCI) remains a solitary construct despite clinical and prognostic heterogeneity. This study aimed to characterize differences in genetic, cerebrospinal fluid (CSF), neuroimaging, and neuropsychological markers across clinician-derived MCI stages. METHODS: Vanderbilt Memory & Aging Project participants with MCI were categorized into 3 severity subtypes at screening based on neuropsychological assessment, functional assessment, and Clinical Dementia Rating interview, including mild (n = 18, 75 ± 8 years), moderate (n = 89 72 ± 7 years), and severe subtypes (n = 18, 78 ± 8 years). At enrollment, participants underwent neuropsychological testing, 3T brain magnetic resonance imaging (MRI), and optional fasting lumbar puncture to obtain CSF. Neuropsychological testing and MRI were repeated at 18-months, 3-years, and 5-years with a mean follow-up time of 3.3 years. Ordinary least square regressions examined cross-sectional associations between MCI severity and apolipoprotein E (APOE)-ε4 status, CSF biomarkers of amyloid beta (Aß), phosphorylated tau, total tau, and synaptic dysfunction (neurogranin), baseline neuroimaging biomarkers, and baseline neuropsychological performance. Longitudinal associations between baseline MCI severity and neuroimaging and neuropsychological trajectory were assessed using linear mixed effects models with random intercepts and slopes and a follow-up time interaction. Analyses adjusted for baseline age, sex, race/ethnicity, education, and intracranial volume for MRI models. RESULTS: Stages differed at baseline on APOE-ε4 status (early < middle = late; p-values < 0.03) and CSF Aß (early > middle = late), phosphorylated and total tau (early = middle < late; p-values < 0.05), and neurogranin concentrations (early = middle < late; p-values < 0.05). MCI stage related to greater longitudinal cognitive decline, hippocampal atrophy, and inferior lateral ventricle dilation (early < late; p-values < 0.03). DISCUSSION: Clinician staging of MCI severity yielded longitudinal cognitive trajectory and structural neuroimaging differences in regions susceptible to AD neuropathology and neurodegeneration. As expected, participants with more severe MCI symptoms at study entry had greater cognitive decline and gray matter atrophy over time. Differences are likely attributable to baseline differences in amyloidosis, tau, and synaptic dysfunction. MCI staging may provide insight into underlying pathology, prognosis, and therapeutic targets.

7.
Circulation ; 138(18): 1951-1962, 2018 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-30018169

RESUMO

BACKGROUND: Mechanisms underlying the association between age-related arterial stiffening and poor brain health remain elusive. Cerebral blood flow (CBF) homeostasis may be implicated. This study evaluates how aortic stiffening relates to resting CBF and cerebrovascular reactivity (CVR) in older adults. METHODS: Vanderbilt Memory & Aging Project participants free of clinical dementia, stroke, and heart failure were studied, including older adults with normal cognition (n=155; age, 72±7 years; 59% male) or mild cognitive impairment (n=115; age, 73±7 years; 57% male). Aortic pulse wave velocity (PWV; meters per second) was quantified from cardiac magnetic resonance. Resting CBF (milliliters per 100 g per minute) and CVR (CBF response to hypercapnic normoxia stimulus) were quantified from pseudocontinuous arterial spin labeling magnetic resonance imaging. Linear regression models related aortic PWV to regional CBF, adjusting for age, race/ethnicity, education, Framingham Stroke Risk Profile (diabetes mellitus, smoking, left ventricular hypertrophy, prevalent cardiovascular disease, atrial fibrillation), hypertension, body mass index, apolipoprotein E4 ( APOE ε4) status, and regional tissue volume. Models were repeated testing PWV× APOE ε4 interactions. Sensitivity analyses excluded participants with prevalent cardiovascular disease and atrial fibrillation. RESULTS: Among participants with normal cognition, higher aortic PWV related to lower frontal lobe CBF (ß=-0.43; P=0.04) and higher CVR in the whole brain (ß=0.11; P=0.02), frontal lobes (ß=0.12; P<0.05), temporal lobes (ß=0.11; P=0.02), and occipital lobes (ß=0.14; P=0.01). Among APOE ε4 carriers with normal cognition, findings were more pronounced with higher PWV relating to lower whole-brain CBF (ß=-1.16; P=0.047), lower temporal lobe CBF (ß=-1.81; P=0.004), and higher temporal lobe CVR (ß=0.26; P=0.08), although the last result did not meet the a priori significance threshold. Results were similar in sensitivity models. Among participants with mild cognitive impairment, higher aortic PWV related to lower CBF in the occipital lobe (ß=-0.70; P=0.02), but this finding was attenuated when participants with prevalent cardiovascular disease and atrial fibrillation were excluded. Among APOE ε4 carriers with mild cognitive impairment, findings were more pronounced with higher PWV relating to lower temporal lobe CBF (ß=-1.20; P=0.02). CONCLUSIONS: Greater aortic stiffening relates to lower regional CBF and higher CVR in cognitively normal older adults, especially among individuals with increased genetic predisposition for Alzheimer's disease. Central arterial stiffening may contribute to reductions in regional CBF despite preserved cerebrovascular reserve capacity.


Assuntos
Circulação Cerebrovascular/fisiologia , Disfunção Cognitiva/patologia , Rigidez Vascular/fisiologia , Idoso , Aorta Torácica/fisiologia , Apolipoproteína E4/genética , Encéfalo/diagnóstico por imagem , Cognição/fisiologia , Feminino , Hemodinâmica , Humanos , Modelos Lineares , Imagem Cinética por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Análise de Onda de Pulso
8.
Acta Neuropathol ; 136(6): 857-872, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-29967939

RESUMO

Cerebrospinal fluid (CSF) levels of amyloid-ß 42 (Aß42) and tau have been evaluated as endophenotypes in Alzheimer's disease (AD) genetic studies. Although there are sex differences in AD risk, sex differences have not been evaluated in genetic studies of AD endophenotypes. We performed sex-stratified and sex interaction genetic analyses of CSF biomarkers to identify sex-specific associations. Data came from a previous genome-wide association study (GWAS) of CSF Aß42 and tau (1527 males, 1509 females). We evaluated sex interactions at previous loci, performed sex-stratified GWAS to identify sex-specific associations, and evaluated sex interactions at sex-specific GWAS loci. We then evaluated sex-specific associations between prefrontal cortex (PFC) gene expression at relevant loci and autopsy measures of plaques and tangles using data from the Religious Orders Study and Rush Memory and Aging Project. In Aß42, we observed sex interactions at one previous and one novel locus: rs316341 within SERPINB1 (p = 0.04) and rs13115400 near LINC00290 (p = 0.002). These loci showed stronger associations among females (ß = - 0.03, p = 4.25 × 10-8; ß = 0.03, p = 3.97 × 10-8) than males (ß = - 0.02, p = 0.009; ß = 0.01, p = 0.20). Higher levels of expression of SERPINB1, SERPINB6, and SERPINB9 in PFC was associated with higher levels of amyloidosis among females (corrected p values < 0.02) but not males (p > 0.38). In total tau, we observed a sex interaction at a previous locus, rs1393060 proximal to GMNC (p = 0.004), driven by a stronger association among females (ß = 0.05, p = 4.57 × 10-10) compared to males (ß = 0.02, p = 0.03). There was also a sex-specific association between rs1393060 and tangle density at autopsy (pfemale = 0.047; pmale = 0.96), and higher levels of expression of two genes within this locus were associated with lower tangle density among females (OSTN p = 0.006; CLDN16 p = 0.002) but not males (p ≥ 0.32). Results suggest a female-specific role for SERPINB1 in amyloidosis and for OSTN and CLDN16 in tau pathology. Sex-specific genetic analyses may improve understanding of AD's genetic architecture.


Assuntos
Doença de Alzheimer , Biomarcadores/líquido cefalorraquidiano , Encéfalo/patologia , Claudinas/genética , Proteínas Musculares/genética , Serpinas/genética , Fatores de Transcrição/genética , Idoso de 80 Anos ou mais , Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Amiloidose/complicações , Amiloidose/genética , Apolipoproteínas E/genética , Encéfalo/metabolismo , Encéfalo/fisiopatologia , Feminino , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Masculino , Mutação/genética , Fragmentos de Peptídeos/líquido cefalorraquidiano , Fatores Sexuais , Proteínas tau/líquido cefalorraquidiano
9.
JAMA Neurol ; 75(8): 989-998, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29801024

RESUMO

Importance: The strongest genetic risk factor for Alzheimer disease (AD), the apolipoprotein E (APOE) gene, has a stronger association among women compared with men. Yet limited work has evaluated the association between APOE alleles and markers of AD neuropathology in a sex-specific manner. Objective: To evaluate sex differences in the association between APOE and markers of AD neuropathology measured in cerebrospinal fluid (CSF) during life or in brain tissue at autopsy. Design, Setting, and Participants: This multicohort study selected data from 10 longitudinal cohort studies of normal aging and AD. Cohorts had variable recruitment criteria and follow-up intervals and included population-based and clinic-based samples. Inclusion in our analysis required APOE genotype data and either CSF data available for analysis. Analyses began on November 6, 2017, and were completed on December 20, 2017. Main Outcomes and Measures: Biomarker analyses included levels of ß-amyloid 42, total tau, and phosphorylated tau measured in CSF. Autopsy analyses included Consortium to Establish a Registry for Alzheimer's Disease staging for neuritic plaques and Braak staging for neurofibrillary tangles. Results: Of the 1798 patients in the CSF biomarker cohort, 862 were women, 226 had AD, 1690 were white, and the mean (SD) age was 70 [9] years. Of the 5109 patients in the autopsy cohort, 2813 were women, 4953 were white, and the mean (SD) age was 84 (9) years. After correcting for multiple comparisons using the Bonferroni procedure, we observed a statistically significant interaction between APOE-ε4 and sex on CSF total tau (ß = 0.41; 95% CI, 0.27-0.55; P < .001) and phosphorylated tau (ß = 0.24; 95% CI, 0.09-0.38; P = .001), whereby APOE showed a stronger association among women compared with men. Post hoc analyses suggested this sex difference was present in amyloid-positive individuals (ß = 0.41; 95% CI, 0.20-0.62; P < .001) but not among amyloid-negative individuals (ß = 0.06; 95% CI, -0.18 to 0.31; P = .62). We did not observe sex differences in the association between APOE and ß-amyloid 42, neuritic plaque burden, or neurofibrillary tangle burden. Conclusions and Relevance: We provide robust evidence of a stronger association between APOE-ε4 and CSF tau levels among women compared with men across multiple independent data sets. Interestingly, APOE-ε4 is not differentially associated with autopsy measures of neurofibrillary tangles. Together, the sex difference in the association between APOE and CSF measures of tau and the lack of a sex difference in the association with neurofibrillary tangles at autopsy suggest that APOE may modulate risk for neurodegeneration in a sex-specific manner, particularly in the presence of amyloidosis.


Assuntos
Doença de Alzheimer/genética , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Apolipoproteínas E/genética , Fragmentos de Peptídeos/líquido cefalorraquidiano , Placa Amiloide/genética , Proteínas tau/líquido cefalorraquidiano , Idoso de 80 Anos ou mais , Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/patologia , Estudos de Coortes , Feminino , Genótipo , Humanos , Masculino , Emaranhados Neurofibrilares/patologia , Fosfoproteínas/líquido cefalorraquidiano , Placa Amiloide/líquido cefalorraquidiano , Placa Amiloide/patologia , Fatores Sexuais
10.
PLoS One ; 12(11): e0188501, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29190651

RESUMO

Biomarker definitions for preclinical Alzheimer's disease (AD) have identified individuals with neurodegeneration (ND+) without ß-amyloidosis (Aß-) and labeled them with suspected non-AD pathophysiology (SNAP). We evaluated Apolipoprotein E (APOE) ε2 and ε4 allele frequencies across biomarker definitions-Aß-/ND- (n = 268), Aß+/ND- (n = 236), Aß-/ND+ or SNAP (n = 78), Aß+/ND+ (n = 204)-hypothesizing that SNAP would have an APOE profile comparable to Aß-/ND-. Using AD Neuroimaging Initiative data (n = 786, 72±7 years, 48% female), amyloid status (Aß+ or Aß-) was defined by cerebrospinal fluid (CSF) Aß-42 levels, and neurodegeneration status (ND+ or ND-) was defined by hippocampal volume from MRI. Binary logistic regression related biomarker status to APOE ε2 and ε4 allele carrier status, adjusting for age, sex, education, and cognitive diagnosis. Compared to the biomarker negative (Aß-/ND-) participants, higher proportions of ε4 and lower proportions of ε2 carriers were observed among Aß+/ND- (ε4: OR = 6.23, p<0.001; ε2: OR = 0.53, p = 0.03) and Aß+/ND+ participants (ε4: OR = 12.07, p<0.001; ε2: OR = 0.29, p = 0.004). SNAP participants were statistically comparable to biomarker negative participants (p-values>0.30). In supplemental analyses, comparable results were observed when coding SNAP using amyloid imaging and when using CSF tau levels. In contrast to APOE, a polygenic risk score for AD that excluded APOE did not show an association with amyloidosis or neurodegeneration (p-values>0.15), but did show an association with SNAP defined using CSF tau (ß = 0.004, p = 0.02). Thus, in a population with low levels of cerebrovascular disease and a lower prevalence of SNAP than the general population, APOE and known genetic drivers of AD do not appear to contribute to the neurodegeneration observed in SNAP. Additional work in population based samples is needed to better elucidate the genetic contributors to various etiological drivers of SNAP.


Assuntos
Doença de Alzheimer/fisiopatologia , Apolipoproteínas E/genética , Frequência do Gene , Sintomas Prodrômicos , Idoso , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/genética , Peptídeos beta-Amiloides/metabolismo , Biomarcadores/metabolismo , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino
11.
Neurology ; 89(23): 2327-2334, 2017 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-29117962

RESUMO

OBJECTIVE: To assess cross-sectionally whether lower cardiac index relates to lower resting cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) among older adults. METHODS: Vanderbilt Memory & Aging Project participants free of stroke, dementia, and heart failure were studied (n = 314, age 73 ± 7 years, 59% male, 39% with mild cognitive impairment). Cardiac index (liters per minute per meter squared) was quantified from echocardiography. Resting CBF (milliliters per 100 grams per minute) and hypercapnia-induced CVR were quantified from pseudo-continuous arterial spin-labeling MRI. Linear regressions with ordinary least-square estimates related cardiac index to regional CBF, with adjustment for age, education, race/ethnicity, Framingham Stroke Risk Profile score (systolic blood pressure, antihypertensive medication use, diabetes mellitus, current cigarette smoking, left ventricular hypertrophy, prevalent cardiovascular disease [CVD], atrial fibrillation), APOE ε4 status, cognitive diagnosis, and regional tissue volume. RESULTS: Lower cardiac index corresponded to lower resting CBF in the left (ß = 2.4, p = 0.001) and right (ß = 2.5, p = 0.001) temporal lobes. Results were similar when participants with prevalent CVD and atrial fibrillation were excluded (left temporal lobe ß = 2.3, p = 0.003; right temporal lobe ß = 2.5, p = 0.003). Cardiac index was unrelated to CBF in other regions assessed (p > 0.25) and CVR in all regions (p > 0.05). In secondary cardiac index × cognitive diagnosis interaction models, cardiac index and CBF associations were present only in cognitively normal participants and affected a majority of regions assessed with effects strongest in the left (p < 0.0001) and right (p < 0.0001) temporal lobes. CONCLUSIONS: Among older adults without stroke, dementia, or heart failure, systemic blood flow correlates with cerebral CBF in the temporal lobe, independently of prevalent CVD, but not CVR.


Assuntos
Débito Cardíaco/fisiologia , Circulação Cerebrovascular/fisiologia , Idoso , Idoso de 80 Anos ou mais , Apolipoproteína E4/genética , Encéfalo/diagnóstico por imagem , Doenças Cardiovasculares/fisiopatologia , Disfunção Cognitiva/complicações , Estudos de Coortes , Estudos Transversais , Eletrocardiografia , Feminino , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Lobo Temporal/irrigação sanguínea
12.
J Alzheimers Dis ; 44(4): 1361-73, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25471188

RESUMO

BACKGROUND: Cardiovascular disease (CVD) and related risk factors are associated with Alzheimer's disease (AD). This association is less well-defined in normal cognition (NC) or prodromal AD (mild cognitive impairment, MCI). OBJECTIVE: Cross-sectionally and longitudinally relate a vascular risk index to cognitive outcomes among elders free of clinical dementia. METHODS: 3,117 MCI (74 ± 8 years, 56% female) and 6,603 NC participants (72 ± 8 years, 68% female) were drawn from the National Alzheimer's Coordinating Center. A composite measure of vascular risk was defined using the Framingham Stroke Risk Profile (FSRP) score (i.e., age, systolic blood pressure, anti-hypertensive medication, diabetes, cigarette smoking, CVD history, atrial fibrillation). Ordinary linear regressions and generalized linear mixed models related baseline FSRP to cross-sectional and longitudinal cognitive outcomes, separately for NC and MCI, adjusting for age, gender, race, education, and follow-up time (in longitudinal models). RESULTS: In NC participants, increasing FSRP was related to worse baseline global cognition, information processing speed, and sequencing abilities (p-values <0.0001) and a worse longitudinal trajectory on all cognitive measures (p-values <0.0001). In MCI, increasing FSRP correlated with worse longitudinal delayed memory (p = 0.004). In secondary models using an age-excluded FSRP score, associations persisted in NC participants for global cognition, naming, information processing speed, and sequencing abilities. CONCLUSIONS: An adverse vascular risk profile is associated with worse cognitive trajectory, especially global cognition, naming, and information processing speed, among NC elders. Future studies are needed to understand how effective management of CVD and related risk factors can modify cognitive decline to identify the ideal timeframe for primary prevention implementation.


Assuntos
Doenças Cardiovasculares/complicações , Transtornos Cognitivos/etiologia , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Feminino , Humanos , Estudos Longitudinais , Masculino , Entrevista Psiquiátrica Padronizada , Testes Neuropsicológicos , Fatores de Risco
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