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1.
Alzheimers Dement ; 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33527648

RESUMO

BACKGROUND: Neurofilament light (NfL) is a promising biomarker of early neurodegeneration in Alzheimer's disease (AD). We examined whether plasma NfL was associated with in vivo amyloid beta and tau, and cognitive performance in non-demented presenilin-1 (PSEN1) E280A mutation carriers. METHODS: Twenty-five mutation carriers and 19 non-carriers (age range: 28 to 49 years) were included in this study. Participants underwent 11C Pittsburgh compound B (PiB)-PET (positron emission tomography), flortaucipir-PET, blood sampling, and cognitive testing. RESULTS: Mutation carriers exhibited higher plasma NfL levels than non-carriers. In carriers, higher NfL levels were related to greater regional tau burden and worse cognition, but not amyloid beta load. When we adjusted for age, a proxy of disease progression, elevated plasma NfL levels were only correlated with worse memory recall. CONCLUSIONS: Findings support an association between plasma NfL, cognition, and tau pathology in non-demented individuals at genetic risk for developing AD dementia. Plasma NfL may be useful for selecting individuals at increased risk and tracking disease progression in AD.

2.
Neurology ; 2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33568538

RESUMO

OBJECTIVE: To examine whether amyloid PET in CN individuals that were screened for the Anti-Amyloid in Asymptomatic AD (A4) study differed across self-identified, non-Hispanic White and Black (NHW and NHB) groups. METHODS: We examined 3689 NHW and 144 NHB that passed initial screening for the A4 study and underwent amyloid PET. The effect of race on amyloid PET was examined using logistic (dichotomous groups) and linear (continuous values) regression controlling for age, sex, and number of APOE ε4 and APOE ε2 alleles. Associations between amyloid and genetically determined ancestry (reflecting African, South Asian, East Asian, American, European populations) were tested within the NHB group. Potential interactions with APOE were assessed. RESULTS: NHB had lower rates of amyloid-positivity and lower continuous amyloid levels compared to NHW. This race effect on amyloid was strongest in the APOE ε4 group. Within NHB, those with a lower percentage of African ancestry had higher amyloid. A greater proportion of NHB did not pass initial screening compared to NHW, suggesting potential sources of bias related to race in the A4 PET data. CONCLUSION: Reduced amyloid was observed in self-identified non-Hispanic Blacks that passed initial eligibility criteria for the A4 Study. This work stresses the importance of investigating AD biomarkers in ancestrally diverse samples as well as the need for careful consideration regarding study eligibility criteria in AD prevention trials.

3.
Neurology ; 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33589537

RESUMO

OBJECTIVE: To determine whether a digital clock drawing test, DCTclock™, improves upon standard cognitive assessments for discriminating diagnostic groups and for detecting biomarker evidence of amyloid and tau pathology in clinically normal older adults (CN). METHODS: Participants from the Harvard Aging Brain Study and the Positron Emission Tomography (PET) lab at Massachusetts General Hospital were recruited to undergo the DCTclock drawing test, standard neuropsychological assessments including the Preclinical Alzheimer Cognitive Composite (PACC), and amyloid /tau PET imaging. Receiver operating curve analyses were used to assess diagnostic and biomarker discriminability. Logistic regression and partial correlations were used to assess DCTclock performance in relation to PACC and PET biomarkers. RESULTS: A total of 300 participants were studied. Among the 264 CN, 143 had amyloid and tau PET imaging (Clinical Dementia Rating=0, Mini Mental State Exam=28.9±1.2). An additional 36 participants with a diagnosis of mild cognitive impairment or early Alzheimer's dementia (CDR=0.5, MMSE=25.2±3.9) were added to assess diagnostic discriminability. DCTclock showed excellent discrimination between diagnostic groups (AUC=0.86). Among CN with biomarkers, the DCTclock summary score and spatial reasoning sub-scores were associated with greater amyloid and tau burden and showed better discrimination (Cohen's d=0.76) between Aß+/- groups than the PACC (d=0.30). CONCLUSION: DCTclock discriminates between diagnostic groups and improves upon traditional cognitive tests for detecting biomarkers of amyloid and tau pathology in CN older adults. The validation of such digitized measures has the potential of providing an efficient tool for detecting early cognitive changes along the AD trajectory. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that the DCTclock results were associated with amyloid and tau burden in clinically normal older adults.

4.
Neurobiol Aging ; 101: 123-129, 2021 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-33610961

RESUMO

KLOTHO∗VS heterozygosity (KL∗VSHET+) was recently shown to be associated with reduced risk of Alzheimer's disease (AD) in APOE∗4 carriers. Additional studies suggest that KL∗VSHET+ protects against amyloid burden in cognitively normal older subjects, but sample sizes were too small to draw definitive conclusions. We performed a well-powered meta-analysis across 5 independent studies, comprising 3581 pre-clinical participants ages 60-80, to investigate whether KL∗VSHET+ reduces the risk of having an amyloid-positive positron emission tomography scan. Analyses were stratified by APOE∗4 status. KL∗VSHET+ reduced the risk of amyloid positivity in APOE∗4 carriers (odds ratio = 0.67 [0.52-0.88]; p = 3.5 × 10-3), but not in APOE∗4 non-carriers (odds ratio = 0.94 [0.73-1.21]; p = 0.63). The combination of APOE∗4 and KL∗VS genotypes should help enrich AD clinical trials for pre-symptomatic subjects at increased risk of developing amyloid aggregation and AD. KL-related pathways may help elucidate protective mechanisms against amyloid accumulation and merit exploration for novel AD drug targets. Future investigation of the biological mechanisms by which KL interacts with APOE∗4 and AD are warranted.

5.
Neuroimage ; 231: 117845, 2021 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33582276

RESUMO

Recent advances in automated face recognition algorithms have increased the risk that de-identified research MRI scans may be re-identifiable by matching them to identified photographs using face recognition. A variety of software exist to de-face (remove faces from) MRI, but their ability to prevent face recognition has never been measured and their image modifications can alter automated brain measurements. In this study, we compared three popular de-facing techniques and introduce our mri_reface technique designed to minimize effects on brain measurements by replacing the face with a population average, rather than removing it. For each technique, we measured 1) how well it prevented automated face recognition (i.e. effects on exceptionally-motivated individuals) and 2) how it altered brain measurements from SPM12, FreeSurfer, and FSL (i.e. effects on the average user of de-identified data). Before de-facing, 97% of scans from a sample of 157 volunteers were correctly matched to photographs using automated face recognition. After de-facing with popular software, 28-38% of scans still retained enough data for successful automated face matching. Our proposed mri_reface had similar performance with the best existing method (fsl_deface) at preventing face recognition (28-30%) and it had the smallest effects on brain measurements in more pipelines than any other, but these differences were modest.

6.
Alzheimers Res Ther ; 13(1): 27, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33451357

RESUMO

BACKGROUND: Neuroimaging studies of autosomal dominant Alzheimer's disease (ADAD) enable characterization of the trajectories of cerebral amyloid-ß (Aß) and tau accumulation in the decades prior to clinical symptom onset. Longitudinal rates of regional tau accumulation measured with positron emission tomography (PET) and their relationship with other biomarker and cognitive changes remain to be fully characterized in ADAD. METHODS: Fourteen ADAD mutation carriers (Presenilin-1 E280A) and 15 age-matched non-carriers from the Colombian kindred underwent 2-3 sessions of Aß (11C-Pittsburgh compound B) and tau (18F-flortaucipir) PET, structural magnetic resonance imaging, and neuropsychological evaluation over a 2-4-year follow-up period. Annualized rates of change for imaging and cognitive variables were compared between carriers and non-carriers, and relationships among baseline measurements and rates of change were assessed within carriers. RESULTS: Longitudinal measurements were consistent with a sequence of ADAD-related changes beginning with Aß accumulation (16 years prior to expected symptom onset, EYO), followed by entorhinal cortex (EC) tau (9 EYO), neocortical tau (6 EYO), hippocampal atrophy (6 EYO), and cognitive decline (4 EYO). Rates of tau accumulation among carriers were most rapid in parietal neocortex (~ 9%/year). EC tau PET signal at baseline was a significant predictor of subsequent neocortical tau accumulation and cognitive decline within carriers. CONCLUSIONS: Our results are consistent with the sequence of biological changes in ADAD implied by cross-sectional studies and highlight the importance of EC tau as an early biomarker and a potential link between Aß burden and neocortical tau accumulation in ADAD.

7.
Sci Transl Med ; 13(577)2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-33472953

RESUMO

Advances in molecular positron emission tomography (PET) have enabled anatomic tracking of brain pathology in longitudinal studies of normal aging and dementia, including assessment of the central model of Alzheimer's disease (AD) pathogenesis, according to which TAU pathology begins focally but expands catastrophically under the influence of amyloid-ß (Aß) pathology to mediate neurodegeneration and cognitive decline. Initial TAU deposition occurs many years before Aß in a specific area of the medial temporal lobe. Building on recent work that enabled focus of molecular PET measurements on specific TAU-vulnerable convolutional temporal lobe anatomy, we applied an automated anatomic sampling method to quantify TAU PET signal in 443 adult participants from several observational studies of aging and AD, spanning a wide range of ages, Aß burdens, and degrees of clinical impairment. We detected initial cortical emergence of tauopathy near the rhinal sulcus in clinically normal people and, in a subset with longitudinal 2-year follow-up data (n = 104), tracked Aß-associated spread of TAU from this site first to nearby neocortex of the temporal lobe and then to extratemporal regions. Greater rate of TAU spread was associated with baseline measures of both global Aß burden and medial temporal lobe TAU. These findings are consistent with clinicopathological correlation studies of Alzheimer's tauopathy and enable precise tracking of AD-related TAU progression for natural history studies and prevention therapeutic trials.

8.
Alzheimers Dement (Amst) ; 12(1): e12118, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33163609

RESUMO

Introduction: We examined the associations among instrumental activities of daily living (IADL), cortical amyloid, and cognition in cognitively normal (CN) older adults. Methods: CN participants screening for the A4 Study (n = 4486) underwent florbetapir (amyloid) positron emission tomography. IADL were assessed using the Alzheimer's Disease Cooperative Study Activities of Daily Living Prevention Instrument. Separate logistic regression models were run with cortical amyloid or cognition as independent variable and IADL as dependent variable, adjusting for age and sex. Results: IADL difficulties were endorsed infrequently (≤16%). Overall IADL and four select IADL item difficulties ("remembering appointments," "finding belongings," "following TV programs," and "remembering current events") reported by both participant and study partner were significantly associated with greater amyloid burden and worse cognition. Discussion: Although IADL deficits were infrequent in this CN cohort, greater participant and study partner report of overall IADL deficits and subtle difficulties in specific IADL items were associated with mildly higher amyloid burden and worse cognition.

9.
Neurology ; 2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-33199430

RESUMO

INTRODUCTION: As clinical trials move towards earlier intervention, we sought to redefine the Aß-PET threshold based on the lowest point in a baseline distribution that robustly predicts future Aß accumulation and cognitive decline in 3 independent samples of clinically normal individuals. METHODS: Sequential Aß cut-offs were tested to identify the lowest cutoff associated with future change in cognition (PACC) and Aß-PET in clinically-normal participants from the Harvard Aging Brain Study (n = 342), Australian Imaging, Biomarker and Lifestyle study of ageing (n = 157) and Alzheimer's Disease Neuroimaging Initiative (n = 356). RESULTS: Within sample, cutoffs derived from future Aß-PET accumulation and PACC decline converged on the same inflection point beyond which trajectories diverged from normal. Across samples, optimal cutoffs fell within a short range (Centiloid 15-18.5). DISCUSSION: These optimized thresholds can help to inform future research and clinical trials targeting early Aß. Threshold convergence raises the possibility of contemporaneous early changes in Aß and cognition. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that among clinically normal individuals a specific Aß-PET threshold is predictive of cognitive decline.

10.
Nat Commun ; 11(1): 6024, 2020 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-33247134

RESUMO

The availability of blood-based assays detecting Alzheimer's disease (AD) pathology should greatly accelerate AD therapeutic development and improve clinical care. This is especially true for markers that capture the risk of decline in pre-symptomatic stages of AD, as this would allow one to focus interventions on participants maximally at risk and at a stage prior to widespread synapse loss and neurodegeneration. Here we quantify plasma concentrations of an N-terminal fragment of tau (NT1) in a large, well-characterized cohort of clinically normal elderly who were followed longitudinally. Plasma NT1 levels at study entry (when all participants were unimpaired) were highly predictive of future cognitive decline, pathological tau accumulation, neurodegeneration, and transition to a diagnosis of MCI/AD. These predictive effects were particularly strong in participants with even modestly elevated brain ß-amyloid burden at study entry, suggesting plasma NT1 levels capture very early cognitive, pathologic and neurodegenerative changes along the AD trajectory.

11.
Alzheimers Res Ther ; 12(1): 138, 2020 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-33121534

RESUMO

BACKGROUND: Impairment in daily functioning is a clinical hallmark of dementia. Difficulties with "instrumental activities of daily living" (IADL) seem to increase gradually over the course of Alzheimer's disease (AD), before dementia onset. However, it is currently not well established how difficulties develop along the preclinical and prodromal stages of AD. We aimed to investigate the trajectories of decline in IADL performance, as reported by a study partner, along the early stages of AD. METHODS: In a longitudinal multicenter study, combining data from community-based and memory clinic cohorts, we included 1555 individuals (mean age 72.5 ± 7.8 years; 50% female) based on availability of amyloid biomarkers, longitudinal IADL data, and clinical information at baseline. Median follow-up duration was 2.1 years. All amyloid-positive participants (n = 982) were classified into the National Institute on Aging-Alzheimer's Association (NIA-AA) clinical stages ranging from preclinical AD (1) to overt dementia (4+). Cognitively normal amyloid-negative individuals (n = 573) served as a comparison group. The total scores of three study-partner reported IADL questionnaires were standardized. RESULTS: The rate of decline in cognitively normal (stage 1) individuals with and without abnormal amyloid did not differ (p = .453). However, from stage 2 onwards, decline was significantly faster in individuals on the AD continuum (B [95%CI] = - 0.32 [- 0.55, - 0.09], p = .007). The rate of decline increased with each successive stage: one standard deviation (SD) unit per year in stage 3 (- 1.06 [- 1.27, - 0.85], p < .001) and nearly two SD units per year in stage 4+ (1.93 [- 2.19, - 1.67], p < .001). Overall, results were similar between community-based and memory clinic study cohorts. CONCLUSIONS: Our results suggest that the rate of functional decline accelerates along the AD continuum, as shown by steeper rates of decline in each successive NIA-AA clinical stage. These results imply that incremental changes in function are a meaningful measure for early disease monitoring. Combined with the low-cost assessment, this advocates the use of these functional questionnaires for capturing the effects of early AD-related cognitive decline on daily life.

12.
J Int Neuropsychol Soc ; : 1-13, 2020 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-33046162

RESUMO

OBJECTIVE: Alzheimer's disease (AD) studies are increasingly targeting earlier (pre)clinical populations, in which the expected degree of observable cognitive decline over a certain time interval is reduced as compared to the dementia stage. Consequently, endpoints to capture early cognitive changes require refinement. We aimed to determine the sensitivity to decline of widely applied neuropsychological tests at different clinical stages of AD as outlined in the National Institute on Aging - Alzheimer's Association (NIA-AA) research framework. METHOD: Amyloid-positive individuals (as determined by positron emission tomography or cerebrospinal fluid) with longitudinal neuropsychological assessments available were included from four well-defined study cohorts and subsequently classified among the NIA-AA stages. For each stage, we investigated the sensitivity to decline of 17 individual neuropsychological tests using linear mixed models. RESULTS: 1103 participants (age = 70.54 ± 8.7, 47% female) were included: n = 120 Stage 1, n = 206 Stage 2, n = 467 Stage 3 and n = 309 Stage 4. Neuropsychological tests were differentially sensitive to decline across stages. For example, Category Fluency captured significant 1-year decline as early as Stage 1 (ß = -.58, p < .001). Word List Delayed Recall (ß = -.22, p < .05) and Trail Making Test (ß = 6.2, p < .05) became sensitive to 1-year decline in Stage 2, whereas the Mini-Mental State Examination did not capture 1-year decline until Stage 3 (ß = -1.13, p < .001) and 4 (ß = -2.23, p < .001). CONCLUSIONS: We demonstrated that commonly used neuropsychological tests differ in their ability to capture decline depending on clinical stage within the AD continuum (preclinical to dementia). This implies that stage-specific cognitive endpoints are needed to accurately assess disease progression and increase the chance of successful treatment evaluation in AD.

13.
Clin Neurophysiol ; 131(11): 2667-2672, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32957039

RESUMO

OBJECTIVE: To investigate neurophysiologic and neuroimaging characteristics of patients with late onset unexplained epilepsy (LOUE). METHODS: We performed a retrospective chart review of elderly patients with ICD9 diagnosis codes consistent with epilepsy/seizures. Inclusion criteria included unprovoked seizures, and absence of cortical lesions on magnetic resonance imaging (MRI). Electroencephalograms (EEGs) findings were also analyzed. MRI images were scored for degree of white matter hyperintensities (Fazekas Scale) and mesial temporal atrophy (MTA). Vascular risk factors, and Framingham Heart Study general cardiovascular disease (FHS-CVD) risk scores were compared to controls from the Harvard Aging Brain study (HABS). RESULTS: We identified 224 LOUE patients and 8% were drug resistant. Epileptiform abnormalities were captured on EEG in 35%. The location was temporal with left sided predominance in 49%. Fazekas scale consisted of 25% beginning of confluent lesions, and 10% large confluent lesions. MTA scores consisted of 21% moderate-severe hippocampal atrophy. LOUE patients had on average a 2.3% (adjusted), 7.4% (unadjusted) increased FHS-CVD score. CONCLUSIONS: Our findings highlight LOUE as pharmacosensitive and left temporal predominant. Given the higher prevalence of vascular risk factors, investigations are needed to study their role in pathophysiology. SIGNIFICANCE: Physicians caring for patients with LOUE should evaluate for vascular risk factors and investigate the presence of hippocampal atrophy.

14.
Neuroimage Clin ; 28: 102407, 2020 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-32942175

RESUMO

Proteinopathies are key elements in the pathogenesis of age-related neurodegenerative diseases, particularly Alzheimer's disease (AD), with the nature and location of the proteinopathy characterizing much of the disease phenotype. Susceptibility of brain regions to pathology may partly be determined by intrinsic network structure and connectivity. It remains unknown, however, how these networks inform the disease cascade in the context of AD biomarkers, such as beta-amyloid (Aß), in clinically-normal older adults.The default-mode network (DMN), a prominent intrinsic network, is heavily implicated in AD due to its spatial overlap with AD atrophy patterns and tau deposition. We investigated the influence of baseline Aß positron emission tomography (PET) signal and intrinsic DMN connectivity on DMN-specific cortical thinning in 120 clinically-normal older adults from the Harvard Aging Brain Study (73 ± 6 years, 58% Female, CDR = 0). Participants underwent11C Pittsburgh Compound-B (PiB) PET, 18F flortaucipir (FTP) PET, and resting-state MRI scans at baselineand longitudinal MRI (3.6 ± 0.96 scans; 5.04 ± 0.8 years). Linear mixed models tested relationships between baseline PiB and DMN connectivity on cortical thinning in a composite of DMN regions. Lower DMN connectivity was associated with faster cortical thinning, but only in those with elevated baseline PiB-PET signal. This relationship was network specific, in that the frontoparietal control network did not account for the observed association. Additionally, the relationship was independent of inferior temporal lobe FTP-PET signal. Our findings provide evidence that compromised DMN connectivity, in the context of preclinical AD, foreshadows neurodegeneration in DMN regions.

15.
Neuroimage Clin ; 28: 102400, 2020 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-32919366

RESUMO

OBJECTIVE: To identify a parsimonious set of markers that optimally predicts subsequent clinical progression from normal to mild cognitive impairment (MCI). METHODS: 250 clinically normal adults (mean age = 73.6 years, SD = 6.0) from the Harvard Aging Brain Study were assessed at baseline on a wide set of markers, including magnetic resonance imaging markers of gray matter thickness and volume, white matter lesions, fractional anisotropy, resting state functional connectivity, positron emission tomography markers of glucose metabolism and ß-amyloid (Aß) burden, and a measure of vascular risk. Participants were also tested annually on a battery of clinical and cognitive tests (median follow-up = 5.0 years, SD = 1.66). We applied least absolute shrinkage and selection operator (LASSO) Cox models to determine the minimum set of non-redundant markers that predicts subsequent clinical progression from normal to MCI, adjusting for age, sex, and education. RESULTS: 23 participants (9.2%) progressed to MCI over the study period (mean years of follow-up to diagnosis = 3.96, SD = 1.89). Progression was predicted by several brain markers, including reduced entorhinal thickness (hazard ratio, HR = 1.73), greater Aß burden (HR = 1.58), lower default network connectivity (HR = 1.42), and smaller hippocampal volume (HR = 1.30). When cognitive test scores were added to the model, the aforementioned neuroimaging markers remained significant and lower striatum volume as well as lower scores on baseline memory and processing speed tests additionally contributed to progression. CONCLUSION: Among a large set of brain, vascular and cognitive markers, a subset of markers independently predicted progression from normal to MCI. These markers may enhance risk stratification by identifying clinically normal individuals who are most likely to develop clinical symptoms and would likely benefit most from therapeutic intervention.

16.
Alzheimers Res Ther ; 12(1): 104, 2020 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-32912283

RESUMO

BACKGROUND: To determine whether performance on the Latin American Spanish version of the Face-Name Associative Memory Exam (LAS-FNAME) can differentiate between cognitively intact carriers of an autosomal dominant Alzheimer's disease mutation (E280A) in Presenilin-1, who are genetically determined to develop early-onset dementia, from matched non-carriers. We also sought to examine whether LAS-FNAME performance is associated with amyloid-ß and regional tau burden in mutation carriers. METHODS: A total of 35 cognitively intact mutation carriers (age range 26-41), 19 symptomatic carriers, and 48 matched non-carriers (age range 27-44) completed a neuropsychological assessment including the LAS-FNAME. A subset of participants (31 carriers [12 symptomatic] and 35 non-carriers) traveled from Colombia to Boston to undergo positron emission tomography (PET) using Pittsburgh compound B to measure mean cortical amyloid-ß and flortaucipir for regional tau. ANOVA analyses and Spearman correlations were used to examine group differences and relationships among LAS-FNAME performance and amyloid-ß and tau accumulation. RESULTS: Compared to non-carriers, cognitively intact mutation carriers had lower scores on the LAS-FNAME Total Scores (p = .040). Across all carriers (including symptomatic carriers), higher levels of amyloid-ß (r = - .436, p = .018) and regional tau in the entorhinal (r = - .394, p = .031) and inferior temporal cortex (r = - .563, p = .001) were associated with lower LAS-FNAME Total Scores. CONCLUSIONS: Performance on the LAS-FNAME differentiated between cognitively intact mutation carriers from non-carriers and was associated with greater amyloid and tau burden when examining all carriers. Findings suggest that the LAS-FNAME is sensitive to early clinical and pathological changes and can potentially help track disease progression in Spanish-speaking individuals.

17.
Brain ; 143(8): 2561-2575, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32844198

RESUMO

Approximately 30% of older adults exhibit the neuropathological features of Alzheimer's disease without signs of cognitive impairment. Yet, little is known about the genetic factors that allow these potentially resilient individuals to remain cognitively unimpaired in the face of substantial neuropathology. We performed a large, genome-wide association study (GWAS) of two previously validated metrics of cognitive resilience quantified using a latent variable modelling approach and representing better-than-predicted cognitive performance for a given level of neuropathology. Data were harmonized across 5108 participants from a clinical trial of Alzheimer's disease and three longitudinal cohort studies of cognitive ageing. All analyses were run across all participants and repeated restricting the sample to individuals with unimpaired cognition to identify variants at the earliest stages of disease. As expected, all resilience metrics were genetically correlated with cognitive performance and education attainment traits (P-values < 2.5 × 10-20), and we observed novel correlations with neuropsychiatric conditions (P-values < 7.9 × 10-4). Notably, neither resilience metric was genetically correlated with clinical Alzheimer's disease (P-values > 0.42) nor associated with APOE (P-values > 0.13). In single variant analyses, we observed a genome-wide significant locus among participants with unimpaired cognition on chromosome 18 upstream of ATP8B1 (index single nucleotide polymorphism rs2571244, minor allele frequency = 0.08, P = 2.3 × 10-8). The top variant at this locus (rs2571244) was significantly associated with methylation in prefrontal cortex tissue at multiple CpG sites, including one just upstream of ATPB81 (cg19596477; P = 2 × 10-13). Overall, this comprehensive genetic analysis of resilience implicates a putative role of vascular risk, metabolism, and mental health in protection from the cognitive consequences of neuropathology, while also providing evidence for a novel resilience gene along the bile acid metabolism pathway. Furthermore, the genetic architecture of resilience appears to be distinct from that of clinical Alzheimer's disease, suggesting that a shift in focus to molecular contributors to resilience may identify novel pathways for therapeutic targets.

18.
Alzheimers Res Ther ; 12(1): 99, 2020 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-32825838

RESUMO

BACKGROUND: Over the past decade, visual short-term memory (VSTM) binding tests have been shown to be one of the most sensitive behavioral indicators of Alzheimer's disease (AD), especially when they require the binding of multiple features (e.g., color and shape). Recently, it has become possible to directly measure amyloid and tau levels in vivo via positron emission tomography (PET). To this point, these behavioral and neurochemical markers have not been compared in humans with AD or at risk for it. METHODS: In a cross-sectional study, we compared VSTM performance to tau and amyloid concentrations, measured by PET, in individuals certain to develop AD by virtue of their inheritance of the presenilin-1 E280A mutation. These included 21 clinically unimpaired subjects and 7 subjects with early mild cognitive impairment (MCI), as well as 30 family members who were not carriers of the mutation. RESULTS: We found that VSTM performance correlated strongly with tau in entorhinal cortex and inferior temporal lobe, and also with amyloid when examining asymptomatic carriers only. The condition requiring binding was not preferentially linked to tau-in fact, the non-binding "shape only" condition showed a stronger relationship. CONCLUSIONS: The results confirm VSTM's status as an early marker of AD pathology and raise interesting questions as to the course of binding-specific versus non-binding aspects of VSTM in early AD.

19.
Ann Neurol ; 88(5): 921-932, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32799367

RESUMO

OBJECTIVE: The goal of this study was to examine sex differences in tau distribution across the brain of older adults, using positron emission tomography (PET), and investigate how these differences might associate with cognitive trajectories. METHODS: Participants were 343 clinically normal individuals (women, 58%; 73.8 [8.5] years) and 55 individuals with mild cognitive impairment (MCI; women, 38%; 76.9 [7.3] years) from the Harvard Aging Brain Study and the Alzheimer's Disease Neuroimaging Initiative. We examined 18 F-Flortaucipir (FTP)-positron emission tomography (PET) signal across 41 cortical and subcortical regions of interest (ROIs). Linear regression models estimated the effect of sex on FTP-signal for each ROI after adjusting for age and cohort. We also examined interactions between sex*Aß-PET positive / negative (+ / -) and sex*apolipoprotein ε4 (APOEε4) status. Linear mixed models estimated the moderating effect of sex on the relationship between a composite of sex-differentiated tau ROIs and cognitive decline. RESULTS: Women showed significantly higher FTP-signals than men across multiple regions of the cortical mantle (p < 0.007). ß-amyloid (Aß)-moderated sex differences in tau signal were localized to medial and inferio-lateral temporal regions (p < 0.007); Aß + women exhibited greater FTP-signal than other groups. APOEε4-moderated sex differences in FTP-signal were only found in the lateral occipital lobe. Women with higher FTP-signals in composite ROI exhibited faster cognitive decline than men (p = 0.04). INTERPRETATION: Tau vulnerability in women is not just limited to the medial temporal lobe and significantly contributed to greater risk of faster cognitive decline. Interactive effects of sex and Aß were predominantly localized in the temporal lobe, however, sex differences in extra-temporal tau highlights the possibility of accelerated tau proliferation in women with the onset of clinical symptomatology. ANN NEUROL 2020;88:921-932.

20.
JAMA Neurol ; 2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32777010

RESUMO

Importance: The goal of preclinical Alzheimer disease (AD) clinical trials is to move diagnosis and treatment to presymptomatic stages, which will require biomarker testing and disclosure. Objective: To assess the short-term psychological outcomes of disclosing amyloid positron emission tomography results to older adults who did not have cognitive impairment. Design, Setting, and Participants: This observational study included participants who were screening for a multisite randomized clinical trial that began on February 28, 2014, and is anticipated to be completed in 2022. Participants aged 65 to 85 years who had no known cognitive impairments underwent an amyloid positron emission tomography scan and learned their result from an investigator who used a protocol-specified process that included prescan education and psychological assessments. This report compares participants with elevated amyloid levels with at least 1 available outcome measure with participants who did not have elevated amyloid levels who enrolled in an observational cohort study and received further evaluations. Data were collected from April 2014 to December 2017 and analyzed from March 2019 to October 2019. Exposures: A personal biomarker result described as either an elevated or not elevated amyloid level. Main Outcomes and Measures: To assess the immediate and short-term psychological outcome of disclosure, the following validated measures were used: the Geriatric Depression Scale, the state items from the State-Trait Anxiety Inventory, and the Columbia Suicide Severity Rating Scale, as well as the Concerns About AD Scale and the Future Time Perspective Scale to assess changes in participants' perceived risk for AD and perceived remaining life span, respectively. Results: A total of 1167 participants with elevated amyloid levels and 538 participants with not elevated amyloid levels were included. Participants had a mean (SD) age of 71.5 (4.7) years, 1025 (60.1%) were women, and most were white (1611 [94.5%]) and non-Latino (1638 [96.1%]). Compared with participants who learned that they had a not elevated amyloid result, individuals who learned of an elevated amyloid result were no more likely to experience short-term increases in depression (mean [SD] change in the Geriatric Depression Scale score, 0.02 [1.3] vs 0.04 [1.3]; P = .90), anxiety (mean [SD] change in State-Trait Anxiety Inventory score, -0.02 [3.2] vs -0.15 [3.0]; P = .65), or suicidality (mean [SD] change in the Columbia Suicide Severity Rating Scale score, 0.0 [0.4] vs -0.01 [0.5]; P = .67). Participants with elevated amyloid levels had increased Concern About AD scores (raw change in scores: elevated amyloid group, 0.8 [3.9]; not elevated amyloid group, -0.4 [3.8]; P < .001). Participants with not elevated amyloid levels experienced a slight increase in Future Time Perspective score(mean [SD] score, 1.15 [7.4] points; P < .001); there was no change in time perspective among those receiving an elevated amyloid result (mean [SD] score, 0.33 [7.8] points). Conclusions and Relevance: In this observational preclinical AD study, participants who learned they had elevated amyloid levels did not experience short-term negative psychological sequelae compared with persons who learned they did not have elevated amyloid levels.

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