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Role of ?-Amyloidosis and Neurodegeneration in Subsequent Imaging Changes in Mild Cognitive Impairment.

ABSTRACT: To understand how a model of Alzheimer disease pathophysiology based on ?-amyloidosis and neurodegeneration predicts the regional anatomic expansion of hypometabolism and atrophy in persons with mild cognitive impairment (MCI).To define the role of ?-amyloidosis and neurodegeneration in the subsequent progression of topographic cortical structural and metabolic changes in MCI.Longitudinal, observational study with serial brain imaging conducted from March 28, 2006, to January 6, 2015, using a population-based cohort. A total of 96 participants with MCI (all aged >70 years) with serial imaging biomarkers from the Mayo Clinic Study of Aging or Mayo Alzheimer's Disease Research Center were included. Participants were characterized initially as having elevated or not elevated brain ?-amyloidosis (A+ or A-) based on 11C-Pittsburgh compound B positron emission tomography. They were further characterized initially by the presence or absence of neurodegeneration (N+ or N-), where the presence of neurodegeneration was defined by abnormally low hippocampal volume or hypometabolism in an Alzheimer disease-like pattern on 18fluorodeoxyglucose (FDG)-positron emission tomography.Regional FDG standardized uptake value ratio (SUVR) and gray matter volumes in medial temporal, lateral temporal, lateral parietal, and medial parietal regions.In the primary regions of interest (ROI), the A+N+ group (n = 45) had lower FDG SUVR at baseline compared with the A+N- group (n = 17) (all 4 ROIs; P

SUBMITTER: Knopman DS

PROVIDER: S-EPMC4735877 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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Role of β-Amyloidosis and Neurodegeneration in Subsequent Imaging Changes in Mild Cognitive Impairment.

Knopman David S DS Jack Clifford R CR Lundt Emily S ES Wiste Heather J HJ Weigand Stephen D SD Vemuri Prashanthi P Lowe Val J VJ Kantarci Kejal K Gunter Jeffrey L JL Senjem Matthew L ML Mielke Michelle M MM Machulda Mary M MM Roberts Rosebud O RO Boeve Bradley F BF Jones David T DT Petersen Ronald C RC

JAMA neurology 20151201 12

<h4>Importance</h4>To understand how a model of Alzheimer disease pathophysiology based on β-amyloidosis and neurodegeneration predicts the regional anatomic expansion of hypometabolism and atrophy in persons with mild cognitive impairment (MCI).<h4>Objective</h4>To define the role of β-amyloidosis and neurodegeneration in the subsequent progression of topographic cortical structural and metabolic changes in MCI.<h4>Design, setting, and participants</h4>Longitudinal, observational study with ser ...[more]

PMID: 26437123

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Project description:OBJECTIVE:To identify a neuroimaging signature predictive of brain amyloidosis as a screening tool to identify individuals with mild cognitive impairment (MCI) that are most likely to have high levels of brain amyloidosis or to be amyloid-free. METHODS:The prediction model cohort included 62 MCI subjects screened with structural magnetic resonance imaging (MRI) and (11) C-labeled Pittsburgh compound B positron emission tomography (PET). We identified an anatomical shape variation-based neuroimaging predictor of brain amyloidosis and defined a structural MRI-based brain amyloidosis score (sMRI-BAS). Amyloid beta positivity (A?(+) ) predictive power of sMRI-BAS was validated on an independent cohort of 153 MCI patients with cerebrospinal fluid A?1-42 biomarker data but no amyloid PET scans. We compared the A?(+) predictive power of sMRI-BAS to those of apolipoprotein E (ApoE) genotype and hippocampal volume, the 2 most relevant candidate biomarkers for the prediction of brain amyloidosis. RESULTS:Anatomical shape variations predictive of brain amyloidosis in MCI embraced a characteristic spatial pattern known for high vulnerability to Alzheimer disease pathology, including the medial temporal lobe, temporal-parietal association cortices, posterior cingulate, precuneus, hippocampus, amygdala, caudate, and fornix/stria terminals. A?(+) prediction performance of sMRI-BAS and ApoE genotype jointly was significantly better than the performance of each predictor separately (area under the curve [AUC] = 0.88 vs AUC = 0.70 and AUC = 0.81, respectively) with >90% sensitivity and specificity at 20% false-positive rate and false-negative rate thresholds. Performance of hippocampal volume as an independent predictor of brain amyloidosis in MCI was only marginally better than random chance (AUC = 0.56). INTERPRETATION:As one of the first attempts to use an imaging technique that does not require amyloid-specific radioligands for identification of individuals with brain amyloidosis, our findings could lead to development of multidisciplinary/multimodality brain amyloidosis biomarkers that are reliable, minimally invasive, and widely available.

Project description:Neuropathological and neuroimaging studies have consistently demonstrated degeneration of monoamine systems, especially the serotonin system, in normal aging and Alzheimer's disease. The evidence for degeneration of the serotonin system in mild cognitive impairment is limited. Thus, the goal of the present study was to measure the serotonin transporter in vivo in mild cognitive impairment and healthy controls. The serotonin transporter is a selective marker of serotonin terminals and of the integrity of serotonin projections to cortical, subcortical and limbic regions and is found in high concentrations in the serotonergic cell bodies of origin of these projections (raphe nuclei). Twenty-eight participants with mild cognitive impairment (age 66.6±6.9, 16 males) and 28 healthy, cognitively normal, demographically matched controls (age 66.2±7.1, 15 males) underwent magnetic resonance imaging for measurement of grey matter volumes and high-resolution positron emission tomography with well-established radiotracers for the serotonin transporter and regional cerebral blood flow. Beta-amyloid imaging was performed to evaluate, in combination with the neuropsychological testing, the likelihood of subsequent cognitive decline in the participants with mild cognitive impairment. The following hypotheses were tested: 1) the serotonin transporter would be lower in mild cognitive impairment compared to controls in cortical and limbic regions, 2) in mild cognitive impairment relative to controls, the serotonin transporter would be lower to a greater extent and observed in a more widespread pattern than lower grey matter volumes or lower regional cerebral blood flow and 3) lower cortical and limbic serotonin transporters would be correlated with greater deficits in auditory-verbal and visual-spatial memory in mild cognitive impairment, not in controls. Reduced serotonin transporter availability was observed in mild cognitive impairment compared to controls in cortical and limbic areas typically affected by Alzheimer's disease pathology, as well as in sensory and motor areas, striatum and thalamus that are relatively spared in Alzheimer's disease. The reduction of the serotonin transporter in mild cognitive impairment was greater than grey matter atrophy or reductions in regional cerebral blood flow compared to controls. Lower cortical serotonin transporters were associated with worse performance on tests of auditory-verbal and visual-spatial memory in mild cognitive impairment, not in controls. The serotonin system may represent an important target for prevention and treatment of MCI, particularly the post-synaptic receptors (5-HT4 and 5-HT6), which may not be as severely affected as presynaptic aspects of the serotonin system, as indicated by the observation of lower serotonin transporters in MCI relative to healthy controls.

Project description:BACKGROUND/OBJECTIVES:Behavioral problems in individuals with Alzheimer's disease (AD) impose major management challenges. Current prevention strategies are anchored to cognitive outcomes, but behavioral outcomes may provide another, clinically relevant opportunity for preemptive therapy. We sought to determine whether personality changes that predispose to behavioral disorders arise during the transition from preclinical AD to mild cognitive impairment (MCI). DESIGN:Longitudinal observational cohort study. SETTING:Academic medical center. PARTICIPANTS:Members of an apolipoprotein E (APOE) ɛ4 genetically enriched cohort of Maricopa County residents who were neuropsychiatrically healthy at entry (N = 277). Over a mean interval of 7 years, 25 who developed MCI and had the Neuroticism, Extraversion, and Openness Personality Inventory-Revised (NEO-PI-R) before and during the MCI transition epoch were compared with 252 nontransitioners also with serial NEO-PI-R administrations. INTERVENTION:Longitudinal administration of the NEO-PI-R and neuropsychological test battery. MEASUREMENTS:Change in NEO-PI-R factor scores (neuroticism, extraversion, openness, agreeableness, conscientiousness) from entry to the epoch of MCI diagnosis or an equivalent follow-up duration in nontransitioners. RESULTS:NEO-PI-R neuroticism T-scores increased significantly more in MCI transitioners than in nontransitioners (mean 2.9, 95% confidence interval (CI) = 0.9-4.9 vs 0, 95% CI = -0.7-0.7, P = .02), and openness decreased more in MCI transitioners than in nontransitioners (-4.8, 95% CI = -7.3 to -2.4 vs -1.0, 95% CI = -1.6 to -0.4, P < .001). Concurrent subclinical but statistically significant changes in behavioral scores worsened more in MCI transitioners than nontransitioners for measures of depression, somatization, irritability, anxiety, and aggressive attitude. CONCLUSION:Personality and subclinical behavioral changes begin during the transition from preclinical AD to incident MCI and qualitatively resemble the clinically manifest behavioral disorders that subsequently arise in individuals with frank dementia.

Dataset Information

Role of ?-Amyloidosis and Neurodegeneration in Subsequent Imaging Changes in Mild Cognitive Impairment.

Publications

Role of β-Amyloidosis and Neurodegeneration in Subsequent Imaging Changes in Mild Cognitive Impairment.

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