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1.
AJNR Am J Neuroradiol ; 38(5): 961-965, 2017 May.
Article in English | MEDLINE | ID: mdl-28279988

ABSTRACT

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.


Subject(s)
Alzheimer Disease/pathology , Amyloid/analysis , Entorhinal Cortex/pathology , Neurofibrillary Tangles/pathology , Aged , Alzheimer Disease/diagnostic imaging , Amyloidosis/pathology , Autopsy , Entorhinal Cortex/diagnostic imaging , Female , Humans , Magnetic Resonance Imaging , Male
2.
Mol Psychiatry ; 22(1): 13-23, 2017 01.
Article in English | MEDLINE | ID: mdl-27872486

ABSTRACT

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.


Subject(s)
Alzheimer Disease/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Muscle Proteins/metabolism , alpha-Macroglobulins/metabolism , Aged , Alzheimer Disease/physiopathology , Amyloid beta-Peptides/metabolism , Apolipoprotein E4/genetics , Biomarkers/cerebrospinal fluid , Brain/metabolism , Calcineurin , Cognition/physiology , Cognition Disorders/metabolism , Cohort Studies , DNA-Binding Proteins , Disease Progression , Female , Gene Expression Regulation/immunology , Humans , Immunity, Innate , Inflammation/cerebrospinal fluid , Longitudinal Studies , Male , Middle Aged , Neuroimaging , Neurons , Phosphorylation , Proteomics , alpha-Macroglobulins/analysis , tau Proteins/metabolism
3.
J Prev Alzheimers Dis ; 3(4): 229-235, 2016.
Article in English | MEDLINE | ID: mdl-29034223

ABSTRACT

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.
Article in English | MEDLINE | ID: mdl-23606904

ABSTRACT

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.


Subject(s)
Asthma/physiopathology , Magnetic Resonance Imaging/methods , Adult , Algorithms , Case-Control Studies , Computational Biology , Female , Forced Expiratory Volume , Helium , Humans , Image Interpretation, Computer-Assisted , Isotopes , Lung/physiopathology , Magnetic Resonance Imaging/statistics & numerical data , Male , Respiratory Function Tests/methods , Respiratory Function Tests/statistics & numerical data , Spirometry , Young Adult
6.
Neurology ; 76(16): 1395-402, 2011 Apr 19.
Article in English | MEDLINE | ID: mdl-21490323

ABSTRACT

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.


Subject(s)
Alzheimer Disease/diagnosis , Alzheimer Disease/physiopathology , Cerebral Cortex/pathology , Cognition/physiology , Dementia/diagnosis , Magnetic Resonance Imaging/methods , Aged , Aged, 80 and over , Biomarkers , Chi-Square Distribution , Disease Progression , Female , Humans , Male , Mental Status Schedule , Predictive Value of Tests , Regression Analysis
7.
Neurology ; 76(17): 1492-9, 2011 Apr 26.
Article in English | MEDLINE | ID: mdl-21518999

ABSTRACT

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.


Subject(s)
Brain/pathology , Cognition Disorders/pathology , Executive Function/physiology , Memory Disorders/pathology , Mental Recall/physiology , Nerve Fibers, Myelinated/pathology , Statistics as Topic , Aged , Aged, 80 and over , Brain Mapping , Female , Humans , Longitudinal Studies , Magnetic Resonance Imaging/methods , Male , Neuropsychological Tests , Residence Characteristics
8.
AJNR Am J Neuroradiol ; 30(3): 532-8, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19112067

ABSTRACT

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.


Subject(s)
Alzheimer Disease/pathology , Cognition Disorders/pathology , Magnetic Resonance Imaging , Parietal Lobe/pathology , Temporal Lobe/pathology , Aged , Alzheimer Disease/epidemiology , Atrophy , Cognition Disorders/epidemiology , Entorhinal Cortex/pathology , Female , Follow-Up Studies , Humans , Male , Multivariate Analysis , Neuropsychological Tests , Predictive Value of Tests , Proportional Hazards Models , Risk Factors , Severity of Illness Index
9.
Neurology ; 71(11): 819-25, 2008 Sep 09.
Article in English | MEDLINE | ID: mdl-18672473

ABSTRACT

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.


Subject(s)
Alzheimer Disease/pathology , Magnetic Resonance Imaging/methods , Parietal Lobe/pathology , Temporal Lobe/pathology , Aged , Alzheimer Disease/metabolism , Atrophy , Female , Follow-Up Studies , Humans , Magnetic Resonance Imaging/standards , Male , Parietal Lobe/metabolism , Research Design/standards , Temporal Lobe/metabolism , Time Factors
10.
Neuroimage ; 39(1): 10-8, 2008 Jan 01.
Article in English | MEDLINE | ID: mdl-17942325

ABSTRACT

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.


Subject(s)
Cerebral Cortex/anatomy & histology , Cerebral Cortex/physiology , Cognition/physiology , Imaging, Three-Dimensional/instrumentation , Magnetic Resonance Imaging/instrumentation , Magnetic Resonance Imaging/methods , Task Performance and Analysis , Aged , Aged, 80 and over , Equipment Design , Equipment Failure Analysis , Female , Humans , Imaging, Three-Dimensional/methods , Male , Organ Size/physiology , Radiation Dosage , Reproducibility of Results , Sensitivity and Specificity , Statistics as Topic
11.
NMR Biomed ; 21(3): 217-25, 2008 Mar.
Article in English | MEDLINE | ID: mdl-17557274

ABSTRACT

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.


Subject(s)
Brain/metabolism , Magnetic Resonance Spectroscopy , Xenon Isotopes/metabolism , Animals , Brain/anatomy & histology , Image Processing, Computer-Assisted , Male , Mathematics , Rats , Rats, Sprague-Dawley
12.
Hippocampus ; 17(11): 1060-70, 2007.
Article in English | MEDLINE | ID: mdl-17604356

ABSTRACT

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.


Subject(s)
Evoked Potentials/physiology , Hippocampus/physiology , Magnetic Resonance Imaging , Mental Recall/physiology , Neocortex/physiology , Prefrontal Cortex/physiology , Psychomotor Performance/physiology , Adult , Data Interpretation, Statistical , Female , Humans , Image Processing, Computer-Assisted , Individuality , Male , Photic Stimulation , Temporal Lobe/physiology
13.
Community Genet ; 10(2): 97-102, 2007.
Article in English | MEDLINE | ID: mdl-17380059

ABSTRACT

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.


Subject(s)
Alzheimer Disease/genetics , Genetic Testing , Health Knowledge, Attitudes, Practice , Adult , Aged , Aged, 80 and over , Apolipoproteins E/genetics , Data Collection , Female , Focus Groups , Genetic Testing/psychology , Humans , Male , Middle Aged , Pilot Projects , Surveys and Questionnaires
14.
J Neurol Neurosurg Psychiatry ; 78(3): 240-7, 2007 Mar.
Article in English | MEDLINE | ID: mdl-17056633

ABSTRACT

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.


Subject(s)
Alzheimer Disease/diagnostic imaging , Cognition Disorders/diagnostic imaging , Tomography, Emission-Computed, Single-Photon , Aged , Aged, 80 and over , Brain/blood supply , Disease Progression , Female , Follow-Up Studies , Humans , Male , Mental Status Schedule , Radiopharmaceuticals , Regional Blood Flow , Technetium Tc 99m Exametazime
15.
Neurology ; 65(3): 404-11, 2005 Aug 09.
Article in English | MEDLINE | ID: mdl-16087905

ABSTRACT

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.


Subject(s)
Aging/physiology , Alzheimer Disease/physiopathology , Cognition Disorders/physiopathology , Hippocampus/physiopathology , Aged , Aging/psychology , Alzheimer Disease/diagnosis , Alzheimer Disease/psychology , Apolipoproteins E/genetics , Cognition Disorders/diagnosis , Cognition Disorders/psychology , Female , Genetic Predisposition to Disease/genetics , Genotype , Humans , Magnetic Resonance Imaging , Male , Memory Disorders/etiology , Memory Disorders/physiopathology , Memory Disorders/psychology , Neuropsychological Tests , Pattern Recognition, Visual/physiology
16.
Neurology ; 62(6): 925-31, 2004 Mar 23.
Article in English | MEDLINE | ID: mdl-15037694

ABSTRACT

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.


Subject(s)
Alzheimer Disease/pathology , Amyloid beta-Peptides/metabolism , Brain/pathology , Gliosis/pathology , Neurofibrillary Tangles/pathology , Synapses/pathology , Aged , Aged, 80 and over , Alzheimer Disease/genetics , Alzheimer Disease/metabolism , Apolipoprotein E4 , Apolipoproteins E/genetics , Biomarkers/analysis , Brain/metabolism , Disease Progression , Glial Fibrillary Acidic Protein/metabolism , Gliosis/metabolism , Humans , Peptide Fragments/metabolism , Predictive Value of Tests , Synaptophysin/metabolism
17.
J Neurol Neurosurg Psychiatry ; 74(1): 44-50, 2003 Jan.
Article in English | MEDLINE | ID: mdl-12486265

ABSTRACT

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.


Subject(s)
Alzheimer Disease/diagnosis , Alzheimer Disease/physiopathology , Association , Brain/physiopathology , Adult , Aged , Aged, 80 and over , Aging/physiology , Association Learning , Brain/pathology , Brain/physiology , Brain Mapping , Female , Hippocampus/pathology , Hippocampus/physiology , Hippocampus/physiopathology , Humans , Magnetic Resonance Imaging , Male , Memory Disorders/diagnosis , Memory Disorders/etiology , Memory Disorders/physiopathology , Photic Stimulation , Predictive Value of Tests , Reference Values
18.
Neurology ; 58(8): 1188-96, 2002 Apr 23.
Article in English | MEDLINE | ID: mdl-11971085

ABSTRACT

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.


Subject(s)
Alzheimer Disease/pathology , Entorhinal Cortex/pathology , Hippocampus/pathology , Aged , Alzheimer Disease/genetics , Alzheimer Disease/psychology , Cognition/physiology , Humans , Longitudinal Studies , Magnetic Resonance Imaging , Neuropsychological Tests
19.
Arch Neurol ; 58(11): 1803-9, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11708987

ABSTRACT

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.


Subject(s)
Dementia/diagnosis , Frontal Lobe/physiopathology , Pick Disease of the Brain/diagnosis , Temporal Lobe/physiopathology , Adult , Aged , Alzheimer Disease/diagnosis , Alzheimer Disease/physiopathology , Dementia/classification , Dementia/pathology , Dementia/physiopathology , Diagnosis, Differential , Female , Frontal Lobe/pathology , Humans , Male , Middle Aged , Phenotype , Pick Disease of the Brain/pathology , Pick Disease of the Brain/physiopathology , Temporal Lobe/pathology
20.
J Am Geriatr Soc ; 49(9): 1168-75, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11559375

ABSTRACT

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.


Subject(s)
Activities of Daily Living , Cognition Disorders/mortality , Geriatric Assessment , Mortality , Aged , Aged, 80 and over , Brazil/epidemiology , Female , Follow-Up Studies , Humans , Logistic Models , Male , Multivariate Analysis , Risk Factors , Urban Population
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