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1.
AJNR Am J Neuroradiol ; 38(5): 961-965, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28279988

RESUMO

BACKGROUND AND PURPOSE: The entorhinal cortex, a critical gateway between the neocortex and hippocampus, is one of the earliest regions affected by Alzheimer disease-associated neurofibrillary tangle pathology. Although our prior work has automatically delineated an MR imaging-based measure of the entorhinal cortex, whether antemortem entorhinal cortex thickness is associated with postmortem tangle burden within the entorhinal cortex is still unknown. Our objective was to evaluate the relationship between antemortem MRI measures of entorhinal cortex thickness and postmortem neuropathological measures. MATERIALS AND METHODS: We evaluated 50 participants from the Rush Memory and Aging Project with antemortem structural T1-weighted MR imaging and postmortem neuropathologic assessments. Here, we focused on thickness within the entorhinal cortex as anatomically defined by our previously developed MR imaging parcellation system (Desikan-Killiany Atlas in FreeSurfer). Using linear regression, we evaluated the association between entorhinal cortex thickness and tangles and amyloid-ß load within the entorhinal cortex and medial temporal and neocortical regions. RESULTS: We found a significant relationship between antemortem entorhinal cortex thickness and entorhinal cortex (P = .006) and medial temporal lobe tangles (P = .002); we found no relationship between entorhinal cortex thickness and entorhinal cortex (P = .09) and medial temporal lobe amyloid-ß (P = .09). We also found a significant association between entorhinal cortex thickness and cortical tangles (P = .003) and amyloid-ß (P = .01). We found no relationship between parahippocampal gyrus thickness and entorhinal cortex (P = .31) and medial temporal lobe tangles (P = .051). CONCLUSIONS: Our findings indicate that entorhinal cortex-associated in vivo cortical thinning may represent a marker of postmortem medial temporal and neocortical Alzheimer disease pathology.


Assuntos
Doença de Alzheimer/patologia , Amiloide/análise , Córtex Entorrinal/patologia , Emaranhados Neurofibrilares/patologia , Idoso , Doença de Alzheimer/diagnóstico por imagem , Amiloidose/patologia , Autopsia , Córtex Entorrinal/diagnóstico por imagem , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino
2.
Mol Psychiatry ; 22(1): 13-23, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27872486

RESUMO

Preclinical changes that precede the onset of symptoms and eventual diagnosis of Alzheimer's disease (AD) are a target for potential preventive interventions. A large body of evidence suggests that inflammation is closely associated with AD pathogenesis and may be a promising target pathway for such interventions. However, little is known about the association between systemic inflammation and preclinical AD pathophysiology. We first examined whether the acute-phase protein, alpha-2 macroglobulin (A2M), a major component of the innate immune system, was associated with cerebrospinal fluid (CSF) markers of neuronal injury in preclinical AD and risk of incident AD in the predictors of cognitive decline among normal individuals (BIOCARD) cohort. We find that A2M concentration in blood is significantly associated with CSF concentrations of the neuronal injury markers, tau and phosphorylated tau, and that higher baseline serum A2M concentration is associated with an almost threefold greater risk of progression to clinical symptoms of AD in men. These findings were replicated in the Alzheimer's Disease Neuroimaging (ADNI) study. Then, utilizing a systems level approach combining large multi-tissue gene expression datasets with mass spectrometry-based proteomic analyses of brain tissue, we identified an A2M gene network that includes regulator of calcineurin (RCAN1), an inhibitor of calcineurin, a well-characterized tau phosphatase. A2M gene and protein expression in the brain were significantly associated with gene and protein expression levels of calcineurin. Collectively these novel findings suggest that A2M is associated with preclinical AD, reflects early neuronal injury in the disease course and may be responsive to tau phosphorylation in the brain through the RCAN1-calcineurin pathway.


Assuntos
Doença de Alzheimer/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas Musculares/metabolismo , alfa-Macroglobulinas/metabolismo , Idoso , Doença de Alzheimer/fisiopatologia , Peptídeos beta-Amiloides/metabolismo , Apolipoproteína E4/genética , Biomarcadores/líquido cefalorraquidiano , Encéfalo/metabolismo , Calcineurina , Cognição/fisiologia , Transtornos Cognitivos/metabolismo , Estudos de Coortes , Proteínas de Ligação a DNA , Progressão da Doença , Feminino , Regulação da Expressão Gênica/imunologia , Humanos , Imunidade Inata , Inflamação/líquido cefalorraquidiano , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Neuroimagem , Neurônios , Fosforilação , Proteômica , alfa-Macroglobulinas/análise , Proteínas tau/metabolismo
3.
J Prev Alzheimers Dis ; 3(4): 229-235, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-29034223

RESUMO

BACKGROUND: Alzheimer's disease (AD) prevention research requires methods for measurement of disease progression not yet revealed by symptoms. Preferably, such measurement should encompass multiple disease markers. OBJECTIVES: Evaluate an item response theory (IRT) model-based latent variable Alzheimer Progression Score (APS) that uses multi-modal disease markers to estimate pre-clinical disease progression. DESIGN: Estimate APS scores in the BIOCARD observational study, and in the parallel PREVENT-AD Cohort and its sister INTREPAD placebo-controlled prevention trial. Use BIOCARD data to evaluate whether baseline and early APS trajectory predict later progression to MCI/dementia. Similarly, use longitudinal PREVENT-AD data to assess test measurement invariance over time. Further, assess portability of the PREVENT-AD IRT model to baseline INTREPAD data, and explore model changes when CSF markers are added or withdrawn. SETTING: BIOCARD was established in 1995 and participants were followed up to 20 years in Baltimore, USA. The PREVENT-AD and INTREPAD trial cohorts were established between 2011-2015 in Montreal, Canada, using nearly identical entry criteria to enroll high-risk cognitively normal persons aged 60+ then followed for several years. PARTICIPANTS: 349 cognitively normal, primarily middle-aged participants in BIOCARD, 125 high-risk participants aged 60+ in PREVENT-AD, and 217 similar subjects in INTREPAD. 106 INTREPAD participants donated up to four serial CSF samples. MEASUREMENTS: Global cognitive assessment and multiple structural, functional, and diffusion MRI metrics, sensori-neural tests, and CSF concentrations of tau, Aß42 and their ratio. RESULTS: Both baseline values and early slope of APS scores in BIOCARD predicted later progression to MCI or AD. Presence of CSF variables strongly improved such prediction. A similarly derived APS in PREVENT-AD showed measurement invariance over time and portability to the parallel INTREPAD sample. CONCLUSIONS: An IRT-based APS can summarize multimodal information to provide a longitudinal measure of pre-clinical AD progression, and holds promise as an outcome for AD prevention trials.

5.
Comput Math Methods Med ; 2013: 624683, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23606904

RESUMO

A segmentation algorithm to isolate areas of ventilation from hyperpolarized helium-3 magnetic resonance imaging (HP (3)He MRI) is described. The algorithm was tested with HP (3)He MRI data from four healthy and six asthmatic subjects. Ventilated lung volume (VLV) measured using our semiautomated technique was compared to that obtained from manual outlining of ventilated lung regions and to standard spirometric measurements. VLVs from both approaches were highly correlated (R = 0.99; P < 0.0001) with a mean difference of 3.8 mL and 95% agreement indices of -30.8 mL and 38.4 mL. There was no significant difference between the VLVs obtained through the semiautomatic approach and the manual approach. A Dice coefficient which quantified the intersection of the two datasets was calculated and ranged from 0.95 to 0.97 with a mean of 0.96 ± 0.01 (mean ± SD). VLVs obtained through the semiautomatic algorithm were also highly correlated with measurements of forced expiratory volume in one second (FEV1) (R = 0.82; P = 0.0035) and forced vital capacity (FVC) (R = 0.95; P < 0.0001). The technique may open new pathways toward advancing more quantitative characterization of ventilation for routine clinical assessment for asthma severity as well as a number of other respiratory diseases.


Assuntos
Asma/fisiopatologia , Imageamento por Ressonância Magnética/métodos , Adulto , Algoritmos , Estudos de Casos e Controles , Biologia Computacional , Feminino , Volume Expiratório Forçado , Hélio , Humanos , Interpretação de Imagem Assistida por Computador , Isótopos , Pulmão/fisiopatologia , Imageamento por Ressonância Magnética/estatística & dados numéricos , Masculino , Testes de Função Respiratória/métodos , Testes de Função Respiratória/estatística & dados numéricos , Espirometria , Adulto Jovem
6.
Neurology ; 76(16): 1395-402, 2011 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-21490323

RESUMO

OBJECTIVE: Since Alzheimer disease (AD) neuropathology is thought to develop years before dementia, it may be possible to detect subtle AD-related atrophy in preclinical AD. Here we hypothesized that the "disease signature" of AD-related cortical thinning, previously identified in patients with mild AD dementia, would be useful as a biomarker to detect anatomic abnormalities consistent with AD in cognitively normal (CN) adults who develop AD dementia after longitudinal follow-up. METHODS: We studied 2 independent samples of adults who were CN when scanned. In sample 1, 8 individuals developing AD dementia (CN-AD converters) after an average of 11.1 years were compared to 25 individuals who remained CN (CN-stable). In sample 2, 7 CN-AD converters (average follow-up 7.1 years) were compared to 25 CN-stable individuals. RESULTS: AD-signature cortical thinning in CN-AD converters in both samples was remarkably similar, about 0.2 mm (p < 0.05). Despite this small absolute difference, Cohen d effect sizes for these differences were very large (> 1). Of the 11 CN individuals with baseline low AD-signature thickness (≥ 1 SD below cohort mean), 55% developed AD dementia over nearly the next decade, while none of the 9 high AD-signature thickness individuals (≥ 1 SD above mean) developed dementia. This marker predicted time to diagnosis of dementia (hazard ratio = 3.4, p < 0.0005); 1 SD of thinning increased dementia risk by 3.4. CONCLUSIONS: By focusing on cortical regions known to be affected in AD dementia, subtle but reliable atrophy is identifiable in asymptomatic individuals nearly a decade before dementia, making this measure a potentially important imaging biomarker of early neurodegeneration.


Assuntos
Doença de Alzheimer/diagnóstico , Doença de Alzheimer/fisiopatologia , Córtex Cerebral/patologia , Cognição/fisiologia , Demência/diagnóstico , Imageamento por Ressonância Magnética/métodos , Idoso , Idoso de 80 Anos ou mais , Biomarcadores , Distribuição de Qui-Quadrado , Progressão da Doença , Feminino , Humanos , Masculino , Entrevista Psiquiátrica Padronizada , Valor Preditivo dos Testes , Análise de Regressão
7.
Neurology ; 76(17): 1492-9, 2011 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-21518999

RESUMO

OBJECTIVES: MRI white matter hyperintensity (WMH) volume is associated with cognitive impairment. We hypothesized that specific loci of WMH would correlate with cognition even after accounting for total WMH volume. METHODS: Subjects were identified from a prospective community-based study: 40 had normal cognition, 94 had mild impairment (defined here as a Clinical Dementia Rating [CDR] score of 0.5 without dementia), and 11 had mild Alzheimer's dementia. Factor analysis of a 22-item neuropsychological battery yielded 4 factors (episodic memory, executive function, spatial skills, and general knowledge). MRI WMH segmentation and analysis was performed using FreeSurfer software. RESULTS: Higher WMH volume was independently associated with lower executive function and episodic memory factor scores. Voxel-based general linear models showed loci where WMH was strongly inversely associated with specific cognitive factor scores (p < 0.001), controlling for age, education, sex, APOE genotype, and total WMH volume. For episodic memory, clusters were observed in bilateral temporal-occipital and right parietal periventricular white matter, and the left anterior limb of the internal capsule. For executive function, clusters were observed in bilateral inferior frontal white matter, bilateral temporal-occipital and right parietal periventricular white matter, and the anterior limb of the internal capsule bilaterally. CONCLUSIONS: Specific WMH loci are closely associated with executive function and episodic memory, independent of total WMH volume. The anatomic locations suggest that WMH may cause cognitive impairment by affecting connections between cortex and subcortical structures, including the thalamus and striatum, or connections between the occipital lobe and frontal or parietal lobes.


Assuntos
Encéfalo/patologia , Transtornos Cognitivos/patologia , Função Executiva/fisiologia , Transtornos da Memória/patologia , Rememoração Mental/fisiologia , Fibras Nervosas Mielinizadas/patologia , Estatística como Assunto , Idoso , Idoso de 80 Anos ou mais , Mapeamento Encefálico , Feminino , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética/métodos , Masculino , Testes Neuropsicológicos , Características de Residência
8.
AJNR Am J Neuroradiol ; 30(3): 532-8, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19112067

RESUMO

BACKGROUND AND PURPOSE: Mild cognitive impairment (MCI) represents a transitional state between normal aging and Alzheimer disease (AD). Our goal was to determine if specific temporoparietal regions can predict the time to progress from MCI to AD. MATERIALS AND METHODS: MR images from 129 individuals with MCI were analyzed to identify the volume of 14 neocortical and 2 non-neocortical brain regions, comprising the temporal and parietal lobes. In addition, 3 neuropsychological test scores were included to determine whether they would provide independent information. After a mean follow-up time of 5 years, 44 of these individuals had progressed to a diagnosis of AD. RESULTS: Cox proportional hazards models demonstrated significant effects for 6 MR imaging regions with the greatest differences being the following: the entorhinal cortex (hazard ratio [HR] = 0.54, P < .001), inferior parietal lobule (hazard ratio [HR] = 0.64, P < .005), and middle temporal gyrus (HR = 0.64, P < .004), indicating decreased risk with larger volumes. A multivariable model showed that a combination of the entorhinal cortex (HR = 0.60, P < .001) and the inferior parietal lobule (HR = 0.62, P < .01) was the best predictor of time to progress to AD. A multivariable model reiterated the importance of including both MR imaging and neuropsychological variables in the final model. CONCLUSIONS: These findings reaffirm the importance of the entorhinal cortex and present evidence for the importance of the inferior parietal lobule as a predictor of time to progress from MCI to AD. The inclusion of neuropsychological performance in the final model continues to highlight the importance of using these measures in a complementary fashion.


Assuntos
Doença de Alzheimer/patologia , Transtornos Cognitivos/patologia , Imageamento por Ressonância Magnética , Lobo Parietal/patologia , Lobo Temporal/patologia , Idoso , Doença de Alzheimer/epidemiologia , Atrofia , Transtornos Cognitivos/epidemiologia , Córtex Entorrinal/patologia , Feminino , Seguimentos , Humanos , Masculino , Análise Multivariada , Testes Neuropsicológicos , Valor Preditivo dos Testes , Modelos de Riscos Proporcionais , Fatores de Risco , Índice de Gravidade de Doença
9.
Neurology ; 71(11): 819-25, 2008 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-18672473

RESUMO

BACKGROUND: MRI studies have demonstrated differential rates of atrophy in the entorhinal cortex and hippocampus during the prodromal phase of Alzheimer disease (AD). The current study was designed to determine whether a broader set of temporoparietal regions show differential rates of atrophy during the evolution of AD. METHODS: Sixteen regions of interest (ROIs) were analyzed on MRI scans obtained at baseline and follow-up in 66 subjects comprising three groups: controls = individuals who were cognitively normal at both baseline and follow-up; nonconverters = subjects with mild cognitive impairment (MCI) at both baseline and follow-up; converters had MCI at baseline but had progressed to AD at follow-up. RESULTS: Annualized percent change was analyzed with multivariate analysis of variance (MANOVA), covaried for age. The MANOVA demonstrated an effect of group (p = 0.004). Post hoc comparisons demonstrated greater rates of atrophy for converters vs nonconverters for six ROIs: hippocampus, entorhinal cortex, temporal pole, middle temporal gyrus, fusiform gyrus, and inferior temporal gyrus. Converters showed differentially greater rates of atrophy than controls in five of the same ROIs (and inferior parietal lobule). Rates of change in clinical status were correlated with the atrophy rates in these regions. Comparisons between controls and nonconverters demonstrated no differences. CONCLUSION: These results demonstrate that temporoparietal regions show differential rates of atrophy on MRI during prodromal Alzheimer disease (AD). MRI data correlate with measures of clinical severity and cognitive decline, suggesting the potential of these regions of interest as antemortem markers of prodromal AD.


Assuntos
Doença de Alzheimer/patologia , Imageamento por Ressonância Magnética/métodos , Lobo Parietal/patologia , Lobo Temporal/patologia , Idoso , Doença de Alzheimer/metabolismo , Atrofia , Feminino , Seguimentos , Humanos , Imageamento por Ressonância Magnética/normas , Masculino , Lobo Parietal/metabolismo , Projetos de Pesquisa/normas , Lobo Temporal/metabolismo , Fatores de Tempo
10.
Neuroimage ; 39(1): 10-8, 2008 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-17942325

RESUMO

In normal humans, relationships between cognitive test performance and cortical structure have received little study, in part, because of the paucity of tools for measuring cortical structure. Computational morphometric methods have recently been developed that enable the measurement of cortical thickness from MRI data, but little data exist on their reliability. We undertook this study to evaluate the reliability of an automated cortical thickness measurement method to detect correlates of interest between thickness and cognitive task performance. Fifteen healthy older participants were scanned four times at 2-week intervals on three different scanner platforms. The four MRI data sets were initially treated independently to investigate the reliability of the spatial localization of findings from exploratory whole-cortex analyses of cortical thickness-cognitive performance correlates. Next, the first data set was used to define cortical ROIs based on the exploratory results that were then applied to the remaining three data sets to determine whether the relationships between cognitive performance and regional cortical thickness were comparable across different scanner platforms and field strengths. Verbal memory performance was associated with medial temporal cortical thickness, while visuomotor speed/set shifting was associated with lateral parietal cortical thickness. These effects were highly reliable - in terms of both spatial localization and magnitude of absolute cortical thickness measurements - across the four scan sessions. Brain-behavior relationships between regional cortical thickness and cognitive task performance can be reliably identified using an automated data analysis system, suggesting that these measures may be useful as imaging biomarkers of disease or performance ability in multicenter studies in which MRI data are pooled.


Assuntos
Córtex Cerebral/anatomia & histologia , Córtex Cerebral/fisiologia , Cognição/fisiologia , Imageamento Tridimensional/instrumentação , Imageamento por Ressonância Magnética/instrumentação , Imageamento por Ressonância Magnética/métodos , Análise e Desempenho de Tarefas , Idoso , Idoso de 80 Anos ou mais , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Humanos , Imageamento Tridimensional/métodos , Masculino , Tamanho do Órgão/fisiologia , Doses de Radiação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Estatística como Assunto
11.
NMR Biomed ; 21(3): 217-25, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17557274

RESUMO

The longitudinal relaxation time of hyperpolarized (HP) (129)Xe in the brain is a critical parameter for developing HP (129)Xe brain imaging and spectroscopy and optimizing the pulse sequences, especially in the case of cerebral blood flow measurements. Various studies have produced widely varying estimates of HP (129)Xe T(1) in the rat brain. To make improved measurements of HP (129)Xe T(1) in the rat brain and investigate how low signal-to-noise ratio (SNR) contributes to these discrepancies, we developed a multi-pulse protocol during the washout of (129)Xe from the brain. Afterwards, we applied an SNR threshold theory to both the multi-pulse protocol and an existing two-pulse protocol. The two protocols yielded mean +/- SD HP (129)Xe T(1) values in the rat brain of 15.3 +/- 1.2 and 16.2 +/- 0.9 s, suggesting that the low SNR might be a key reason for the wide range of T(1) values published in the literature, a problem that might be easily alleviated by taking SNR levels into account.


Assuntos
Encéfalo/metabolismo , Espectroscopia de Ressonância Magnética , Isótopos de Xenônio/metabolismo , Animais , Encéfalo/anatomia & histologia , Processamento de Imagem Assistida por Computador , Masculino , Matemática , Ratos , Ratos Sprague-Dawley
12.
Hippocampus ; 17(11): 1060-70, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17604356

RESUMO

The ability to spontaneously recall recently learned information is a fundamental mnemonic activity of daily life, but has received little study using functional neuroimaging. We developed a functional MRI (fMRI) paradigm to study regional brain activity during encoding that predicts free recall. In this event-related fMRI study, ten lists of fourteen pictures of common objects were shown to healthy young individuals and regional brain activity during encoding was analyzed based on subsequent free recall performance. Free recall of items was predicted by activity during encoding in hippocampal, fusiform, and inferior prefrontal cortical regions. Within-subject variance in free recall performance for the ten lists was predicted by a linear combination of condition-specific inferior prefrontal, hippocampal, and fusiform activity. Recall performance was better for lists in which prefrontal activity was greater for all items of the list and hippocampal and fusiform activity were greater specifically for items that were recalled from the list. Thus, the activity of medial temporal, fusiform, and prefrontal brain regions during the learning of new information is important for the subsequent free recall of this information. These fronto-temporal brain regions act together as a large-scale memory-related network, the components of which make distinct yet interacting contributions during encoding that predict subsequent successful free recall performance.


Assuntos
Potenciais Evocados/fisiologia , Hipocampo/fisiologia , Imageamento por Ressonância Magnética , Rememoração Mental/fisiologia , Neocórtex/fisiologia , Córtex Pré-Frontal/fisiologia , Desempenho Psicomotor/fisiologia , Adulto , Interpretação Estatística de Dados , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Individualidade , Masculino , Estimulação Luminosa , Lobo Temporal/fisiologia
13.
Community Genet ; 10(2): 97-102, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17380059

RESUMO

OBJECTIVES: In preparation for the development of an educational intervention on Alzheimer disease (AD) genetics, we undertook a pilot survey of knowledge in this area and attitudes toward genetic testing for AD among individuals with a family history of AD. METHODS: For the pilot study, we administered a 30-min questionnaire to 57 unaffected individuals from a genetic linkage study. For the focus groups, we interviewed two groups of subjects, ages 44-70 years, with a family history of AD, one of 10 Caucasians and the other of 6 African-Americans. RESULTS: The pilot study showed that there was limited knowledge of genetics overall and AD genetics in particular, considerable concern about personal risk, and little knowledge of or interest in genetic testing for the disease. The focus groups reinforced and fleshed out these impressions and highlighted the importance of caregiving experience in the attitudes toward personal risk for AD. CONCLUSIONS: These results underscore the value of genetics education for this and other complex diseases and suggest specific foci for educational interventions.


Assuntos
Doença de Alzheimer/genética , Testes Genéticos , Conhecimentos, Atitudes e Prática em Saúde , Adulto , Idoso , Idoso de 80 Anos ou mais , Apolipoproteínas E/genética , Coleta de Dados , Feminino , Grupos Focais , Testes Genéticos/psicologia , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Inquéritos e Questionários
14.
J Neurol Neurosurg Psychiatry ; 78(3): 240-7, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17056633

RESUMO

OBJECTIVE: To relate cerebral perfusion abnormalities to subsequent changes in clinical status among patients with mild cognitive impairment (MCI). METHODS: Perfusion single photon emission computed tomography (SPECT) images were acquired in 105 elderly patients without dementia with MCI, using 99mTc-HMPAO. Clinical outcome after a 5-year follow-up period was heterogeneous. RESULTS: Baseline SPECT data differed in those patients with MCI who were later diagnosed with Alzheimer's disease (the converter group) from those patients with MCI who experienced clinically evident decline but did not progress to a diagnosis of Alzheimer's disease within the follow-up period (the decliner group), from patients with MCI who had no clinical evidence of progression (the stable group), and from a group of 19 normal subjects (the control group). The most consistent decreases in relative perfusion in converters compared with the normal, stable and decliner groups were observed in the caudal anterior cingulate, and in the posterior cingulate. In addition, converters showed increased relative perfusion in the rostral anterior cingulate in comparison to the stable and decliner groups. A group of patients with Alzheimer's disease were also included for purposes of comparison. The group of patients with Alzheimer's disease at baseline differed from each of the other groups, with temporoparietal regions showing the most significant reductions in perfusion. CONCLUSIONS: These results suggest that clinical heterogeneity in MCI is reflected in SPECT perfusion differences, and that the pattern of perfusion abnormalities evolves with increasing clinical severity.


Assuntos
Doença de Alzheimer/diagnóstico por imagem , Transtornos Cognitivos/diagnóstico por imagem , Tomografia Computadorizada de Emissão de Fóton Único , Idoso , Idoso de 80 Anos ou mais , Encéfalo/irrigação sanguínea , Progressão da Doença , Feminino , Seguimentos , Humanos , Masculino , Entrevista Psiquiátrica Padronizada , Compostos Radiofarmacêuticos , Fluxo Sanguíneo Regional , Tecnécio Tc 99m Exametazima
15.
Neurology ; 65(3): 404-11, 2005 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-16087905

RESUMO

OBJECTIVE: To use fMRI to investigate whether hippocampal and entorhinal activation during learning is altered in the earliest phase of mild cognitive impairment (MCI). METHODS: Three groups of older individuals were studied: 10 cognitively intact controls, 9 individuals at the mild end of the spectrum of MCI, and 10 patients with probable Alzheimer disease (AD). Subjects performed a face-name associative encoding task during fMRI scanning, and were tested for recognition of stimuli afterward. Data were analyzed using a functional-anatomic method in which medial temporal lobe (MTL) regions of interest were identified from each individual's structural MRI, and fMRI activation was quantified within each region. RESULTS: Significantly greater hippocampal activation was present in the MCI group compared to controls; there were no differences between these two groups in hippocampal or entorhinal volumes. In contrast, the AD group showed hippocampal and entorhinal hypoactivation and atrophy in comparison to controls. The subjects with MCI performed similarly to controls on the fMRI recognition memory task; patients with AD exhibited poorer performance. Across all 29 subjects, greater mean entorhinal activation was found in the subgroup of 13 carriers of the APOE epsilon4 allele than in the 16 noncarriers. CONCLUSIONS: The authors hypothesize that there is a phase of increased medial temporal lobe activation early in the course of prodromal Alzheimer disease followed by a subsequent decrease as the disease progresses.


Assuntos
Envelhecimento/fisiologia , Doença de Alzheimer/fisiopatologia , Transtornos Cognitivos/fisiopatologia , Hipocampo/fisiopatologia , Idoso , Envelhecimento/psicologia , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/psicologia , Apolipoproteínas E/genética , Transtornos Cognitivos/diagnóstico , Transtornos Cognitivos/psicologia , Feminino , Predisposição Genética para Doença/genética , Genótipo , Humanos , Imageamento por Ressonância Magnética , Masculino , Transtornos da Memória/etiologia , Transtornos da Memória/fisiopatologia , Transtornos da Memória/psicologia , Testes Neuropsicológicos , Reconhecimento Visual de Modelos/fisiologia
16.
Neurology ; 62(6): 925-31, 2004 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-15037694

RESUMO

BACKGROUND: Pathologic changes in the Alzheimer disease (AD) brain occur in a hierarchical neuroanatomical pattern affecting cortical, subcortical, and limbic regions. OBJECTIVE: To define the time course of pathologic and biochemical changes-amyloid deposition, amyloid beta-peptide (Abeta) accumulation, neurofibrillary tangle (NFT) formation, synaptic loss, and gliosis-within the temporal association cortex of AD cases of varying disease duration, relative to control brains. METHODS: Stereologic assessments of amyloid burden and tangle density as well as ELISA-based measurements of Abeta, synaptophysin, and glial fibrillary acidic protein (GFAP) were performed in the superior temporal sulcus from a cohort of 83 AD and 26 nondemented control brains. RESULTS: Relative to control cases, AD brains were characterized by accumulation of NFT and amyloid plaques, increase of tris- and formic acid-extractable Abeta species, reduced levels of synaptophysin, and elevated levels of GFAP. In AD cases, the duration of dementia correlated with the degree of tangle formation, gliosis, and synaptic loss but not with any Abeta measures. Accumulation of Abeta, measured both neuropathologically and biochemically, was markedly increased in AD brains independent of disease duration, even in cases of short duration. CONCLUSIONS: These data support distinct processes in the initiation and progression of AD pathology within the temporal cortex: Deposition of Abeta reaches a "ceiling" early in the disease process, whereas NFT formation, synaptic loss, and gliosis continue throughout the course of the illness.


Assuntos
Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Encéfalo/patologia , Gliose/patologia , Emaranhados Neurofibrilares/patologia , Sinapses/patologia , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Apolipoproteína E4 , Apolipoproteínas E/genética , Biomarcadores/análise , Encéfalo/metabolismo , Progressão da Doença , Proteína Glial Fibrilar Ácida/metabolismo , Gliose/metabolismo , Humanos , Fragmentos de Peptídeos/metabolismo , Valor Preditivo dos Testes , Sinaptofisina/metabolismo
17.
J Neurol Neurosurg Psychiatry ; 74(1): 44-50, 2003 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-12486265

RESUMO

OBJECTIVE: To examine alterations in patterns of brain activation seen in normal aging and in mild Alzheimer's disease by functional magnetic resonance imaging (fMRI) during an associative encoding task. METHODS: 10 young controls, 10 elderly controls, and seven patients with mild Alzheimer's disease were studied using fMRI during a face-name association encoding task. The fMRI paradigm used a block design with three conditions: novel face-name pairs, repeated face-name pairs, and visual fixation. RESULTS: The young and elderly controls differed primarily in the pattern of activation seen in prefrontal and parietal cortices: elderly controls showed significantly less activation in both superior and inferior prefrontal cortices but greater activation in parietal regions than younger controls during the encoding of novel face-name pairs. Compared with elderly controls, the Alzheimer patients showed significantly less activation in the hippocampal formation but greater activation in the medial parietal and posterior cingulate regions. CONCLUSIONS: The pattern of fMRI activation during the encoding of novel associations is differentially altered in the early stages of Alzheimer's disease compared with normal aging.


Assuntos
Doença de Alzheimer/diagnóstico , Doença de Alzheimer/fisiopatologia , Associação , Encéfalo/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/fisiologia , Aprendizagem por Associação , Encéfalo/patologia , Encéfalo/fisiologia , Mapeamento Encefálico , Feminino , Hipocampo/patologia , Hipocampo/fisiologia , Hipocampo/fisiopatologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Transtornos da Memória/diagnóstico , Transtornos da Memória/etiologia , Transtornos da Memória/fisiopatologia , Estimulação Luminosa , Valor Preditivo dos Testes , Valores de Referência
18.
Neurology ; 58(8): 1188-96, 2002 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-11971085

RESUMO

BACKGROUND: MRI measures of the entorhinal cortex and the hippocampus have been used to predict which nondemented individuals with memory problems will progress to meet criteria for AD on follow-up, but their relative accuracy remains controversial. OBJECTIVES: To compare MRI measures of the entorhinal cortex and the hippocampus for predicting who will develop AD. METHODS: MRI volumes of the entorhinal cortex and the hippocampus were obtained in 137 individuals comprising four groups: 1) individuals with normal cognition both at baseline and after 3 years of follow-up (n = 28), 2) subjects with memory difficulty but not dementia both at baseline and after 3 years of follow-up (n = 73), 3) subjects with memory difficulty at baseline who were diagnosed with probable AD within 3 years of follow-up (n = 21), and 4) patients with mild AD at baseline (n = 16). RESULTS: Measures of both the entorhinal cortex and the hippocampus were different for each of the pairwise comparisons between the groups (p < 0.001) and were correlated with tests of memory (p < 0.01). However, the volume of the entorhinal cortex differentiated the subjects from those destined to develop dementia with considerable accuracy (84%), whereas the measure of the hippocampus did not. CONCLUSION: These findings are consistent with neuropathologic data showing substantial involvement of the entorhinal cortex in the preclinical phase of AD and suggest that, as the disease spreads, atrophic change develops within the hippocampus, which is measurable on MRI.


Assuntos
Doença de Alzheimer/patologia , Córtex Entorrinal/patologia , Hipocampo/patologia , Idoso , Doença de Alzheimer/genética , Doença de Alzheimer/psicologia , Cognição/fisiologia , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética , Testes Neuropsicológicos
19.
Arch Neurol ; 58(11): 1803-9, 2001 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11708987

RESUMO

An international group of clinical and basic scientists participated in the Frontotemporal Dementia and Pick's Disease Criteria Conference at the National Institutes of Health in Bethesda, Md, on July 7, 2000, to reassess clinical and neuropathological criteria for the diagnosis of frontotemporal dementia (FTD). Previous criteria for FTD have primarily been designed for research purposes. The goal of this meeting was to propose guidelines that would enable clinicians (particularly neurologists, psychiatrists, and neuropsychologists) to recognize patients with FTD and, if appropriate, to expedite their referral to a diagnostic center. In addition, recommendations for the neuropathological criteria of FTD were reviewed, relative to classical neuropathology and modern molecular biology.


Assuntos
Demência/diagnóstico , Lobo Frontal/fisiopatologia , Doença de Pick/diagnóstico , Lobo Temporal/fisiopatologia , Adulto , Idoso , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/fisiopatologia , Demência/classificação , Demência/patologia , Demência/fisiopatologia , Diagnóstico Diferencial , Feminino , Lobo Frontal/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Doença de Pick/patologia , Doença de Pick/fisiopatologia , Lobo Temporal/patologia
20.
J Am Geriatr Soc ; 49(9): 1168-75, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11559375

RESUMO

OBJECTIVES: To identify a set of predictors of mortality among residents in the community, before any physical, biochemical, or image examination is performed, that could be collected on a routine standardized basis, to help the clinician define a patient follow-up strategy and the health planner make decisions regarding the care of older people. DESIGN: A household follow-up study, with an evaluation at baseline and 2 years later. SETTING: Residential area, with a low rate of in- and outmigration, in Sao Paulo, a large industrialized urban center in southeastern Brazil. PARTICIPANTS: One thousand six hundred sixty-seven older urban residents in the community (65+), from different socioeconomic backgrounds, enrolled after a study area census. INTERVENTION: Structured home interview with Brazilian Older Americans Resources and Services Multidimensional Functional Assessment Questionnaire, previously validated in Portuguese. MEASUREMENTS: A logistic regression model for the risk of dying in the period was developed, having as independent variables, sociodemographic characteristics plus six other dimensions: subjective self-evaluation of health, past medical history, use of health services, dependence in activities of daily living (ADLs), mental health, and cognitive status. RESULTS: There were 146 deaths (9%) in the cohort during the follow-up interval. The variables that appeared as independent predictors of death in the final logistic regression model were: gender (relative risk (RR) = 2.8 (males)), age (RR = 2.0 (80+ vs. 65-69)), hospitalization in the previous 6 months (RR = 2.4 (at least one)), dependence in ADLs (RR = 3.0 (assistance required for 7 vs. 0 ADLs)); and cognitive impairment (RR = 1.9 (Mini-Mental State Examination 18 vs. 30)). CONCLUSION: These findings suggest that in developing countries such as Brazil, an assessment of dependence in daily living and cognitive status should be an essential part of any health evaluation of an older person, not only because these variables represent potentially high independent mortality risks, but also because they can be easily and reliably assessed, using well-validated instruments, and may be susceptible to intervention.


Assuntos
Atividades Cotidianas , Transtornos Cognitivos/mortalidade , Avaliação Geriátrica , Mortalidade , Idoso , Idoso de 80 Anos ou mais , Brasil/epidemiologia , Feminino , Seguimentos , Humanos , Modelos Logísticos , Masculino , Análise Multivariada , Fatores de Risco , População Urbana
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