PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-25 (47)
 

Clipboard (0)
None

Select a Filter Below

Year of Publication
Document Types
1.  The Alzheimer’s Prevention Initiative composite cognitive test score: Sample size estimates for the evaluation of preclinical Alzheimer’s disease treatments in presenilin 1 E280A mutation carriers 
Objective
There is a need to identify a cognitive composite that is sensitive to tracking preclinical AD decline to be used as a primary endpoint in treatment trials.
Method
We capitalized on longitudinal data, collected from 1995 to 2010, from cognitively unimpaired presenilin 1 (PSEN1) E280A mutation carriers from the world’s largest known early-onset autosomal dominant AD (ADAD) kindred to identify a composite cognitive test with the greatest statistical power to track preclinical AD decline and estimate the number of carriers age 30 and older needed to detect a treatment effect in the Alzheimer’s Prevention Initiative’s (API) preclinical AD treatment trial. The mean-to-standard-deviation ratios (MSDRs) of change over time were calculated in a search for the optimal combination of one to seven cognitive tests/sub-tests drawn from the neuropsychological test battery in cognitively unimpaired mutation carriers during a two and five year follow-up period, using data from non-carriers during the same time period to correct for aging and practice effects. Combinations that performed well were then evaluated for robustness across follow-up years, occurrence of selected items within top performing combinations and representation of relevant cognitive domains.
Results
This optimal test combination included CERAD Word List Recall, CERAD Boston Naming Test (high frequency items), MMSE Orientation to Time, CERAD Constructional Praxis and Ravens Progressive Matrices (Set A) with an MSDR of 1.62. This composite is more sensitive than using either the CERAD Word List Recall (MSDR=0.38) or the entire CERAD-Col battery (MSDR=0.76). A sample size of 75 cognitively normal PSEN1-E280A mutation carriers age 30 and older per treatment arm allows for a detectable treatment effect of 29% in a 60-month trial (80% power, p=0.05).
Conclusions
We have identified a composite cognitive test score representing multiple cognitive domains that has improved power compared to the most sensitive single test item to track preclinical AD decline in ADAD mutation carriers and evaluate preclinical AD treatments. This API composite cognitive test score will be used as the primary endpoint in the first API trial in cognitively unimpaired ADAD carriers within 15 years of their estimated age at clinical onset. We have independently confirmed our findings in a separate cohort of cognitively healthy older adults who progressed to the clinical stages of late-onset AD, described in a separate report, and continue to refine the composite in independent cohorts and compared with other analytical approaches.
doi:10.4088/JCP.13m08927
PMCID: PMC4331113  PMID: 24816373
composite cognitive score; API; Alzheimer’s Prevention Initiative; E280A; PSEN1; presenilin1; sample size; preclinical; cognitively unimpaired; autosomal dominant; ADAD
2.  Subjective Cognitive Decline: Self and Informant Comparisons 
Background
It is unclear whether self or informant-based subjective cognition better distinguishes emotional factors from early stage Alzheimer’s disease (AD).
Methods
447 healthy members of the Arizona Apolipoprotein E (APOE) Cohort and their informants completed both the self and informant paired Multidimensional Assessment of Neurodegenerative Symptoms questionnaire (MANS).
Results
30.6% of members and 26.2% of informants endorsed decline on the MANS. Both self and informant-based decliners had higher scores of psychological distress and slightly lower cognitive scores than nondecliners. Over the next 6.7 years, 20 developed mild cognitive impairment (MCI). Converters were older at entry than nonconverters (63.8[7.0] vs 58.8[7.3] years, p=.003), 85% were APOE e4 carriers (p<.0001), and they self-endorsed decline earlier than informants (58.9[39.2] vs 28.0[40.4] months before MCI; p=.002).
Conclusions
Both self and informant based subjective decline correlated with greater psychological distress, and slightly lower cognitive performance. Those with incident MCI generally self-endorsed decline earlier than informants.
doi:10.1016/j.jalz.2013.01.003
PMCID: PMC3732500  PMID: 23562429
3.  The neuropsychology of normal aging and preclinical Alzheimer’s disease 
Background
An NIA-sponsored workgroup on preclinical Alzheimer’s disease (AD) articulated the need to characterize cognitive differences between normal aging and preclinical AD.
Methods
71 apolipoprotein E (APOE) e4 homozygotes (HMZ), 194 e3/4 heterozygotes (HTZ), and 356 e4 noncarriers (NC) aged 21–87 years who were cognitively healthy underwent neuropsychological testing every two years. Longitudinal trajectories of test scores were compared between APOE subgroups.
Results
There was a significant effect of age on all cognitive domains in both APOE e4 carriers and NC. A significant effect of APOE e4 gene dose was confined to the memory domain and the Dementia Rating Scale. Cross sectional comparisons did not discriminate the groups.
Conclusions
While cognitive aging patterns are similar in APOE e4 carriers and NC, preclinical AD is characterized by a significant e4 gene dose effect that impacts memory and is detectable longitudinally. Preclinical neuropsychological testing strategies should emphasize memory sensitive measures and longitudinal design.
doi:10.1016/j.jalz.2013.01.004
PMCID: PMC3700591  PMID: 23541188
preclinical Alzheimer’s disease; cognitive aging; age-related memory loss; mild cognitive impairment; apolipoprotein E; longitudinal testing
4.  Fibrillar Amyloid Correlates of Preclinical Cognitive Decline 
Background
It is not known whether preclinical cognitive decline is associated with fibrillar β-amyloid (Aβ) deposition irrespective of Apolipoprotein E (APOE) ε4 status.
Methods
From a prospective observational study of 623 cognitively normal individuals, we identified all subjects who showed preclinical decline of at least 2 standard deviations beyond the decline of the entire group in memory or executive function. Fourteen decliners were matched by APOE ε4 gene dose, age, sex, and education with 14 nondecliners. Dynamic Pittsburgh compound B (PiB) positron emission tomography (PET) scans, the Logan method, statistical parametric mapping, and automatically labeled regions of interest were used to characterize and compare cerebral-to-cerebellar PiB distribution volume ratios (DVR), reflecting fibrillar Aβ burden.
Results
At P<.005 (uncorrected), decliners had significantly greater DVR’s in comparison to nondecliners.
Conclusions
Asymptomatic longitudinal neuropsychological decline is associated with subsequent increased fibrillar amyloid deposition, even when controlling for APOE ε4 genotype.
doi:10.1016/j.jalz.2013.01.009
PMCID: PMC3713087  PMID: 23583233
preclinical; Alzheimer’s disease; amyloid imaging; cognitive decline; Apolipoprotein E
5.  Neuropathologic Heterogeneity Does Not Impair Florbetapir-PET Postmortem Correlates 
Neuropathologic heterogeneity is often present within Alzheimer’s disease (AD). We sought to determine if amyloid imaging measures of AD are affected by concurrent pathologies. Thirty-eight clinicopathologically-defined AD and 17 non-demented cases (ND) with quantitative florbetapir F-18 (18F-AV-45) PET imaging during life and histological β-amyloid quantification and neuropathologic examination were assessed. AD cases were divided on the basis of concurrent pathologies, including those with Lewy bodies (N=21), white matter rarefaction (N=27), severe cerebral amyloid angiopathy (N=11), argyrophilic grains (N=5) and TDP-43 inclusions (N=18). Many cases exhibited more than one type of concurrent pathology. The ratio of cortical to cerebellar amyloid imaging signal (SUVr) and immunohistochemical β-amyloid load were analyzed in six cortical regions of interest. All AD subgroups had strong and significant correlations between SUVr and histological β-amyloid measures (p values <0.001). All AD subgroups had significantly greater amyloid measures compared to ND, and mean amyloid measures did not significantly differ between AD subgroups. When comparing AD cases with and without each pathology, AD cases with Lewy bodies had significantly decreased SUVr measures compared to AD cases without (p = 0.002); there were no other paired comparison differences. These findings indicate florbetapir-PET imaging is not confounded by neuropathological heterogeneity within AD.
doi:10.1097/NEN.0000000000000028
PMCID: PMC4037918  PMID: 24335535
argyrophilic grains; autopsy; cerebral amyloid angiopathy; Lewy bodies; plaques; TDP-43; vascular dementia; white matter; leuko-araiosis
6.  Brain Differences in Infants at Differential Genetic Risk for Late-Onset Alzheimer Disease A Cross-sectional Imaging Study 
JAMA neurology  2014;71(1):11-22.
IMPORTANCE
Converging evidence suggests brain structure alterations may precede overt cognitive impairment in Alzheimer disease by several decades. Early detection of these alterations holds inherent value for the development and evaluation of preventive treatment therapies.
OBJECTIVE
To compare magnetic resonance imaging measurements of white matter myelin water fraction (MWF) and gray matter volume (GMV) in healthy infant carriers and noncarriers of the apolipoprotein E (APOE) ε4 allele, the major susceptibility gene for late-onset AD.
DESIGN, SETTING, AND PARTICIPANTS
Quiet magnetic resonance imaging was performed at an academic research imaging center on 162 healthy, typically developing 2- to 25-month-old infants with no family history of Alzheimer disease or other neurological or psychiatric disorders. Cross-sectional measurements were compared in the APOE ε4 carrier and noncarrier groups. White matter MWF was compared in one hundred sixty-two 2- to 25-month-old sleeping infants (60 ε4 carriers and 102 noncarriers). Gray matter volume was compared in a subset of fifty-nine 6- to 25-month-old infants (23 ε4 carriers and 36 noncarriers), who remained asleep during the scanning session. The carrier and noncarrier groups were matched for age, gestational duration, birth weight, sex ratio, maternal age, education, and socioeconomic status.
MAIN OUTCOMES AND MEASURES
Automated algorithms compared regional white matter MWF and GMV in the carrier and noncarrier groups and characterized their associations with age.
RESULTS
Infant ε4 carriers had lower MWF and GMV measurements than noncarriers in precuneus, posterior/middle cingulate, lateral temporal, and medial occipitotemporal regions, areas preferentially affected by AD, and greater MWF and GMV measurements in extensive frontal regions and measurements were also significant in the subset of 2- to 6-month-old infants (MWF differences, P < .05, after correction for multiple comparisons; GMV differences, P < .001, uncorrected for multiple comparisons). Infant ε4 carriers also exhibited an attenuated relationship between MWF and age in posterior white matter regions.
CONCLUSIONS AND RELEVANCE
While our findings should be considered preliminary, this study demonstrates some of the earliest brain changes associated with the genetic predisposition to AD. It raises new questions about the role of APOE in normal human brain development, the extent to which these processes are related to subsequent AD pathology, and whether they could be targeted by AD prevention therapies.
doi:10.1001/jamaneurol.2013.4544
PMCID: PMC4056558  PMID: 24276092
7.  BRAIN ABNORMALITIES IN YOUNG ADULTS AT GENETIC RISK FOR AUTOSOMAL DOMINANT ALZHEIMER’S DISEASE: A CROSS-SECTIONAL STUDY 
The Lancet. Neurology  2012;11(12):1048-1056.
Summary
Background
We previously detected functional brain imaging abnormalities in young adults at genetic risk for late-onset Alzheimer’s disease (AD). Here, we sought to characterize structural and functional magnetic resonance imaging (MRI), cerebrospinal fluid (CSF), and plasma biomarker abnormalities in young adults at risk for autosomal dominant early-onset AD. Biomarker measurements were characterized and compared in presenilin 1 (PSEN1) E280A mutation carriers and non-carriers from the world’s largest known autosomal dominant early-onset AD kindred, more than two decades before the carriers’ estimated median age of 44 at the onset of mild cognitive impairment (MCI) and before their estimated age of 28 at the onset of amyloid-β (Aβ) plaque deposition.
Methods
Biomarker data for this cross-sectional study were acquired in Antioquia, Colombia between July and August, 2010. Forty-four participants from the Colombian Alzheimer’s Prevention Initiative (API) Registry had structural MRIs, functional MRIs during associative memory encoding/novel viewing and control tasks, and cognitive assessments. They included 20 mutation carriers and 24 non-carriers, who were cognitively normal, 18-26 years old and matched for their gender, age, and educational level. Twenty of the participants, including 10 mutation carriers and 10 non-carriers, had lumbar punctures and venipunctures. Primary outcome measures included task-dependent hippocampal/parahippocampal activations and precuneus/posterior cingulate deactivations, regional gray matter reductions, CSF Aβ1-42, total tau and phospho-tau181 levels, and plasma Aβ1-42 levels and Aβ1-42/Aβ1-40 ratios. Structural and functional MRI data were compared using automated brain mapping algorithms and AD-related search regions. Cognitive and fluid biomarkers were compared using Mann-Whitney tests.
Findings
The mutation carrier and non-carrier groups did not differ significantly in their dementia ratings, neuropsychological test scores, or proportion of apolipoprotein E (APOE) ε4 carriers. Compared to the non-carriers, carriers had higher CSF Aβ1-42 levels (p=0·008), plasma Aβ1-42 levels (p=0·01), and plasma Aβ1-42/Aβ1-40 ratios (p=0·001), consistent with Aβ1-42 overproduction. They also had greater hippocampal/parahippocampal activations (as low as p=0·008, after correction for multiple comparisons), less precuneus/posterior cingulate deactivations (as low as p=0·001, after correction), less gray matter in several regions (p-values <0·005, uncorrected, and corrected p=0·008 in the parietal search region), similar to findings in the later preclinical and clinical stages of autosomal dominant and late-onset AD.
Interpretation
Young adults at genetic risk for autosomal dominant AD have functional and structural MRI abnormalities, along with CSF and plasma biomarker findings consistent with Aβ1-42 over-production. While the extent to which the underlying brain changes are progressive or developmental remain to be determined, this study demonstrates the earliest known biomarker changes in cognitively normal people at genetic risk for autosomal dominant AD.
Funding
Banner Alzheimer’s Foundation, Nomis Foundation, Anonymous Foundation, Forget Me Not Initiative, Boston University Department of Psychology, Colciencias (1115-408-20512, 1115-545-31651), National Institute on Aging (R01 AG031581, P30 AG19610, UO1 AG024904, RO1 AG025526, RF1AG041705), National Institute of Neurological Disorders and Stroke (F31-NS078786) and state of Arizona.
doi:10.1016/S1474-4422(12)70228-4
PMCID: PMC4181671  PMID: 23137948
Alzheimer’s disease; biomarkers; preclinical; early-onset; dominantly inherited; MRI; functional MRI; cerebrospinal fluid; plasma; presenilin E280A mutation; amyloid; tau; genetics; prevention
8.  Genetic Susceptibility for Alzheimer’s Disease Neuritic Plaque Pathology 
JAMA neurology  2013;70(9):1150-1157.
Objective
To investigate whether Alzheimer’s disease (AD) susceptibility loci from genome-wide association studies (GWAS) impact neuritic plaque pathology and to additionally identify novel risk loci for this trait.
Design
Candidate analysis of single nucleotide polymorphisms (SNPs) and GWAS in a joint clinicopathologic cohort study, followed by targeted validation in independent neuroimaging cohorts.
Participants and Setting
725 deceased subjects from the Religious Orders and Rush Memory and Aging Project, two prospective, community-based studies of aging; the validation neuroimaging cohort consisted of 114 subjects from multiple clinical and research centers.
Main Outcome Measures
A quantitative measure of neuritic plaque pathologic burden, based on assessments of silver-stained tissue averaged from multiple brain regions. Validation based on β-amyloid load by immunocytochemistry, and replication with fibrillar β-amyloid Positron Emission Tomography (PET) imaging with Pittsburgh Compound B or florbetapir.
Results
Besides the previously reported APOE and CR1 loci, we find that ABCA7 (rs3764650, P=0.02) and CD2AP (rs9349407, P=0.03) AD susceptibility loci are associated with neuritic plaque burden. In addition, among the top results of our GWAS, we discovered a novel variant near the amyloid precursor protein gene (APP, rs2829887) that is associated with neuritic plaques (P=3.3×10−6). This polymorphism was associated with postmortem β-amyloid load, as well as fibrillar β-amyloid in two independent cohorts of adults with normal cognition.
Conclusion
These findings enhance understanding of AD risk factors by relating validated susceptibility alleles to increased neuritic plaque pathology and implicate common genetic variation at the APP locus in the earliest, pre-symptomatic stages of AD.
doi:10.1001/jamaneurol.2013.2815
PMCID: PMC3773291  PMID: 23836404
9.  USHERING IN THE STUDY AND TREATMENT OF PRECLINICAL ALZHEIMER DISEASE 
Nature reviews. Neurology  2013;9(7):371-381.
Researchers have begun to characterize the subtle biological and cognitive processes that precede the clinical onset of Alzheimer disease (AD), and to set the stage for accelerated evaluation of experimental treatments to delay the onset, reduce the risk of or completely prevent clinical decline. Here, we provide an overview of the experimental strategies, and brain imaging and cerebrospinal fluid biomarker measures that are used in early detection and tracking of AD, highlighting at-risk individuals who could be suitable for preclinical monitoring. We discuss how these advances have contributed to reconceptualization of AD as a sequence of biological changes that occur during progression from preclinical AD, to mild cognitive impairment and finally dementia, and we review recently proposed research criteria for preclinical AD. Advances in the study of preclinical AD have driven the recognition that efficacy of at least some AD therapies may depend on initiation of treatment before clinical manifestation of disease, leading to a new era of AD prevention research.
doi:10.1038/nrneurol.2013.107
PMCID: PMC4084675  PMID: 23752908
10.  The Receiver Operational Characteristic for Binary Classification with Multiple Indices and Its Application to the Neuroimaging Study of Alzheimer’s Disease 
Given a single index, the receiver operational characteristic (ROC) curve analysis is routinely utilized for characterizing performances in distinguishing two conditions/groups in terms of sensitivity and specificity. Given the availability of multiple data sources (referred to as multi-indices), such as multimodal neuroimaging data sets, cognitive tests, and clinical ratings and genomic data in Alzheimer’s disease (AD) studies, the single-index-based ROC underutilizes all available information. For a long time, a number of algorithmic/analytic approaches combining multiple indices have been widely used to simultaneously incorporate multiple sources. In this study, we propose an alternative for combining multiple indices using logical operations, such as “AND,” “OR,” and “at least n” (where n is an integer), to construct multivariate ROC (multiV-ROC) and characterize the sensitivity and specificity statistically associated with the use of multiple indices. With and without the “leave-one-out” cross-validation, we used two data sets from AD studies to showcase the potentially increased sensitivity/specificity of the multiV-ROC in comparison to the single-index ROC and linear discriminant analysis (an analytic way of combining multi-indices). We conclude that, for the data sets we investigated, the proposed multiV-ROC approach is capable of providing a natural and practical alternative with improved classification accuracy as compared to univariate ROC and linear discriminant analysis.
doi:10.1109/TCBB.2012.141
PMCID: PMC4085147  PMID: 23702553
Alzheimer’s dementia (AD); multiple indices; multiV-ROC; receiver operational characteristic (ROC)
11.  Brain Differences in Infants at Differential Genetic Risk for Late-Onset Alzheimer Disease 
JAMA neurology  2014;71(1):11-22.
IMPORTANCE
Converging evidence suggests brain structure alterations may precede overt cognitive impairment in Alzheimer disease by several decades. Early detection of these alterations holds inherent value for the development and evaluation of preventive treatment therapies.
OBJECTIVE
To compare magnetic resonance imaging measurements of white matter myelin water fraction (MWF) and gray matter volume (GMV) in healthy infant carriers and noncarriers of the apolipoprotein E (APOE) ε4 allele, the major susceptibility gene for late-onset AD.
DESIGN, SETTING, AND PARTICIPANTS
Quiet magnetic resonance imaging was performed at an academic research imaging center on 162 healthy, typically developing 2- to 25-month-old infants with no family history of Alzheimer disease or other neurological or psychiatric disorders. Cross-sectional measurements were compared in the APOE ε4 carrier and noncarrier groups. White matter MWF was compared in one hundred sixty-two 2- to 25-month-old sleeping infants (60 ε4 carriers and 102 noncarriers). Gray matter volume was compared in a subset of fifty-nine 6- to 25-month-old infants (23 ε4 carriers and 36 noncarriers), who remained asleep during the scanning session. The carrier and noncarrier groups were matched for age, gestational duration, birth weight, sex ratio, maternal age, education, and socioeconomic status.
MAIN OUTCOMES AND MEASURES
Automated algorithms compared regional white matter MWF and GMV in the carrier and noncarrier groups and characterized their associations with age.
RESULTS
Infant ε4 carriers had lower MWF and GMV measurements than noncarriers in precuneus, posterior/middle cingulate, lateral temporal, and medial occipitotemporal regions, areas preferentially affected by AD, and greater MWF and GMV measurements in extensive frontal regions and measurements were also significant in the subset of 2- to 6-month-old infants (MWF differences, P < .05, after correction for multiple comparisons; GMV differences, P < .001, uncorrected for multiple comparisons). Infant ε4 carriers also exhibited an attenuated relationship between MWF and age in posterior white matter regions.
CONCLUSIONS AND RELEVANCE
While our findings should be considered preliminary, this study demonstrates some of the earliest brain changes associated with the genetic predisposition to AD. It raises new questions about the role of APOE in normal human brain development, the extent to which these processes are related to subsequent AD pathology, and whether they could be targeted by AD prevention therapies.
doi:10.1001/jamaneurol.2013.4544
PMCID: PMC4056558  PMID: 24276092
12.  Higher serum glucose levels are associated with cerebral hypometabolism in Alzheimer regions 
Neurology  2013;80(17):1557-1564.
Objective:
To investigate whether higher fasting serum glucose levels in cognitively normal, nondiabetic adults were associated with lower regional cerebral metabolic rate for glucose (rCMRgl) in brain regions preferentially affected by Alzheimer disease (AD).
Methods:
This is a cross-sectional study of 124 cognitively normal persons aged 64 ± 6 years with a first-degree family history of AD, including 61 APOEε4 noncarriers and 63 carriers. An automated brain mapping algorithm characterized and compared correlations between higher fasting serum glucose levels and lower [18F]-fluorodeoxyglucose-PET rCMRgl measurements.
Results:
As predicted, higher fasting serum glucose levels were significantly correlated with lower rCMRgl and were confined to the vicinity of brain regions preferentially affected by AD. A similar pattern of regional correlations occurred in the APOEε4 noncarriers and carriers.
Conclusions:
Higher fasting serum glucose levels in cognitively normal, nondiabetic adults may be associated with AD pathophysiology. Findings suggest that the risk imparted by higher serum glucose levels may be independent of APOEε4 status. This study raises additional questions about the role of the metabolic process in the predisposition to AD and supports the possibility of targeting these processes in presymptomatic AD trials.
doi:10.1212/WNL.0b013e31828f17de
PMCID: PMC3662330  PMID: 23535495
13.  Amyloid deposition detected with florbetapir F 18 (18F-AV-45) is related to lower episodic memory performance in clinically normal older individuals 
Neurobiology of aging  2012;34(3):822-831.
The objective of this study was to evaluate the relationship of amyloid burden, as assessed by florbetapir F 18 (18F-AV-45) amyloid PET, and cognition in healthy older control subjects (HC). Seventy-eight HC subjects were assessed with a brief cognitive test battery and PET imaging with florbetapir F 18. A standard uptake value ratio (SUVr) was computed for mean data from six cortical regions using a whole cerebellum reference region. Scans were also visually rated as amyloid positive (Aβ+) or amyloid negative (Aβ−) by three readers. Higher SUVr correlated with lower immediate memory (r=−0.33; p=0.003) and delayed recall scores (r=−0.25; p=0.027). Performance on immediate recall was also lower in the visually rated Aβ+ compared to Aβ− HC (p=0.04), with a similar trend observed in delayed recall (p=0.06). These findings support the hypothesis that higher amyloid burden is associated with lower memory performance among clinically normal older subjects. Longitudinal follow-up is ongoing to determine whether florbetapir F 18 may also predict subsequent cognitive decline.
doi:10.1016/j.neurobiolaging.2012.06.014
PMCID: PMC3518678  PMID: 22878163
14.  A Sparse Structure Learning Algorithm for Gaussian Bayesian Network Identification from High-Dimensional Data 
Structure learning of Bayesian Networks (BNs) is an important topic in machine learning. Driven by modern applications in genetics and brain sciences, accurate and efficient learning of large-scale BN structures from high-dimensional data becomes a challenging problem. To tackle this challenge, we propose a Sparse Bayesian Network (SBN) structure learning algorithm that employs a novel formulation involving one L1-norm penalty term to impose sparsity and another penalty term to ensure that the learned BN is a Directed Acyclic Graph (DAG)—a required property of BNs. Through both theoretical analysis and extensive experiments on 11 moderate and large benchmark networks with various sample sizes, we show that SBN leads to improved learning accuracy, scalability, and efficiency as compared with 10 existing popular BN learning algorithms. We apply SBN to a real-world application of brain connectivity modeling for Alzheimer’s disease (AD) and reveal findings that could lead to advancements in AD research.
doi:10.1109/TPAMI.2012.129
PMCID: PMC3924722  PMID: 22665720
Bayesian network; machine learning; data mining
15.  Florbetapir PET analysis of amyloid-β deposition in the presenilin 1 E280A autosomal dominant Alzheimer’s disease kindred: a cross-sectional study 
Lancet neurology  2012;11(12):10.1016/S1474-4422(12)70227-2.
Summary
Background
Fibrillar amyloid-β (Aβ) is thought to begin accumulating in the brain many years before the onset of clinical impairment in patients with Alzheimer’s disease. By assessing the accumulation of Aβ in people at risk of genetic forms of Alzheimer’s disease, we can identify how early preclinical changes start in individuals certain to develop dementia later in life. We sought to characterise the age-related accumulation of Aβ deposition in presenilin 1 (PSEN1) E280A mutation carriers across the spectrum of preclinical disease.
Methods
Between Aug 1 and Dec 6, 2011, members of the familial Alzheimer’s disease Colombian kindred aged 18–60 years were recruited from the Alzheimer’s Prevention Initiative’s registry at the University of Antioquia, Medellín, Colombia. Cross-sectional assessment using florbetapir PET was done in symptomatic mutation carriers with mild cognitive impairment or mild dementia, asymptomatic carriers, and asymptomatic non-carriers. These assessments were done at the Banner Alzheimer’s Institute in Phoenix, AZ, USA. A cortical grey matter mask consisting of six predefined regions. was used to measure mean cortical florbetapir PET binding. Cortical-to-pontine standard-uptake value ratios were used to characterise the cross-sectional accumulation of fibrillar Aβ deposition in carriers and non-carriers with regression analysis and to estimate the trajectories of fibrillar Aβ deposition.
Findings
We enrolled a cohort of 11 symptomatic individuals, 19 presymptomatic mutation carriers, and 20 asymptomatic non-carriers, ranging in age from 20 to 56 years. There was greater florbetapir binding in asymptomatic PSEN1 E280A mutation carriers than in age matched non-carriers. Fibrillar Aβ began to accumulate in PSEN 1E280A mutation carriers at a mean age of 28·2 years (95% CI 27·3–33·4), about 16 years and 21 years before the predicted median ages at mild cognitive impairment and dementia onset, respectively. 18F florbetapir binding rose steeply over the next 9·4 years and plateaued at a mean age of 37·6 years (95% CI 35·3–40·2), about 6 and 11 years before the expected respective median ages at mild cognitive impairment and dementia onset. Prominent florbetapir binding was seen in the anterior and posterior cingulate, precuneus, and parietotemporal and frontal grey matter, as well as in the basal ganglia. Binding in the basal ganglia was not seen earlier or more prominently than in other regions.
Interpretation
These findings contribute to the understanding of preclinical familial Alzheimer’s disease and help set the stage for assessment of amyloid-modifying treatments in the prevention of familial Alzheimer’s disease.
Funding
Avid Radiopharmaceuticals, Banner Alzheimer’s Foundation, Nomis Foundation, Anonymous Foundation, Forget Me Not Initiative, Colciencias, National Institute on Aging, and the State of Arizona.
doi:10.1016/S1474-4422(12)70227-2
PMCID: PMC3515078  PMID: 23137949
16.  Amyloid-β assessed by florbetapir F 18 PET and 18-month cognitive decline 
Neurology  2012;79(16):1636-1644.
Objectives:
Florbetapir F 18 PET can image amyloid-β (Aβ) aggregates in the brains of living subjects. We prospectively evaluated the prognostic utility of detecting Aβ pathology using florbetapir PET in subjects at risk for progressive cognitive decline.
Methods:
A total of 151 subjects who previously participated in a multicenter florbetapir PET imaging study were recruited for longitudinal assessment. Subjects included 51 with recently diagnosed mild cognitive impairment (MCI), 69 cognitively normal controls (CN), and 31 with clinically diagnosed Alzheimer disease dementia (AD). PET images were visually scored as positive (Aβ+) or negative (Aβ−) for pathologic levels of β-amyloid aggregation, blind to diagnostic classification. Cerebral to cerebellar standardized uptake value ratios (SUVr) were determined from the baseline PET images. Subjects were followed for 18 months to evaluate changes in cognition and diagnostic status. Analysis of covariance and correlation analyses were conducted to evaluate the association between baseline PET amyloid status and subsequent cognitive decline.
Results:
In both MCI and CN, baseline Aβ+ scans were associated with greater clinical worsening on the Alzheimer's Disease Assessment Scale–Cognitive subscale (ADAS-Cog (p < 0.01) and Clinical Dementia Rating–sum of boxes (CDR-SB) (p < 0.02). In MCI Aβ+ scans were also associated with greater decline in memory, Digit Symbol Substitution (DSS), and Mini-Mental State Examination (MMSE) (p < 0.05). In MCI, higher baseline SUVr similarly correlated with greater subsequent decline on the ADAS-Cog (p < 0.01), CDR-SB (p < 0.03), a memory measure, DSS, and MMSE (p < 0.05). Aβ+ MCI tended to convert to AD dementia at a higher rate than Aβ− subjects (p < 0.10).
Conclusions:
Florbetapir PET may help identify individuals at increased risk for progressive cognitive decline.
doi:10.1212/WNL.0b013e3182661f74
PMCID: PMC3468774  PMID: 22786606
17.  Clinical and multimodal biomarker correlates of ADNI neuropathological findings 
Background
Autopsy series commonly report a high percentage of coincident pathologies in demented patients, including patients with a clinical diagnosis of dementia of the Alzheimer type (DAT). However many clinical and biomarker studies report cases with a single neurodegenerative disease. We examined multimodal biomarker correlates of the consecutive series of the first 22 Alzheimer’s Disease Neuroimaging Initiative autopsies. Clinical data, neuropsychological measures, cerebrospinal fluid Aβ, total and phosphorylated tau and α-synuclein and MRI and FDG-PET scans.
Results
Clinical diagnosis was either probable DAT or Alzheimer’s disease (AD)-type mild cognitive impairment (MCI) at last evaluation prior to death. All patients had a pathological diagnosis of AD, but only four had pure AD. A coincident pathological diagnosis of dementia with Lewy bodies (DLB), medial temporal lobe pathology (TDP-43 proteinopathy, argyrophilic grain disease and hippocampal sclerosis), referred to collectively here as MTL, and vascular pathology were present in 45.5%, 40.0% and 22.7% of these patients, respectively. Hallucinations were a strong predictor of coincident DLB (100% specificity) and a more severe dysexecutive profile was also a useful predictor of coincident DLB (80.0% sensitivity and 83.3% specificity). Occipital FDG-PET hypometabolism accurately classified coincident DLB (80% sensitivity and 100% specificity). Subjects with coincident MTL showed lower hippocampal volume.
Conclusions
Biomarkers can be used to independently predict coincident AD and DLB pathology, a common finding in amnestic MCI and DAT patients. Cohorts with comprehensive neuropathological assessments and multimodal biomarkers are needed to characterize independent predictors for the different neuropathological substrates of cognitive impairment.
doi:10.1186/2051-5960-1-65
PMCID: PMC3893373  PMID: 24252435
Alzheimer’s disease; Mild cognitive impairment; CSF; MRI; Autopsy; Neuropathology; Dementia; Biomarkers; Amyloid; Tau
18.  Posterior Cingulate Glucose Metabolism, Hippocampal Glucose Metabolism, and Hippocampal Volume in Cognitively Normal, Late-Middle-Aged Persons at 3 Levels of Genetic Risk for Alzheimer Disease 
JAMA neurology  2013;70(3):320-325.
Objective
To characterize and compare measurements of the posterior cingulate glucose metabolism, the hippocampal glucose metabolism, and hippocampal volume so as to distinguish cognitively normal, late-middle-aged persons with 2, 1, or 0 copies of the apolipoprotein E (APOE) ε4 allele, reflecting 3 levels of risk for late-onset Alzheimer disease.
Design
Cross-sectional comparison of measurements of cerebral glucose metabolism using 18F-fluorodeoxy-glucose positron emission tomography and measurements of brain volume using magnetic resonance imaging in cognitively normal ε4 homozygotes, ε4 heterozygotes, and noncarriers.
Setting
Academic medical center.
Participants
A total of 31 ε4 homozygotes, 42 ε4 heterozygotes, and 76 noncarriers, 49 to 67 years old, matched for sex, age, and educational level.
Main Outcome Measures
The measurements of posterior cingulate and hippocampal glucose metabolism were characterized using automated region-of-interest algorithms and normalized for whole-brain measurements. The hippocampal volume measurements were characterized using a semiautomated algorithm and normalized for total intracranial volume.
Results
Although there were no significant differences among the 3 groups of participants in their clinical ratings, neuropsychological test scores, hippocampal volumes (P=.60), or hippocampal glucose metabolism measurements (P = .12), there were significant group differences in their posterior cingulate glucose metabolism measurements (P=.001). The APOE ε4 gene dose was significantly associated with posterior cingulate glucose metabolism (r=0.29, P=.0003), and this association was significantly greater than those with hippocampal volume or hippocampal glucose metabolism (P<.05, determined by use of pairwise Fisher z tests).
Conclusions
Although our findings may depend in part on the analysis algorithms used, they suggest that a reduction in posterior cingulate glucose metabolism precedes a reduction in hippocampal volume or metabolism in cognitively normal persons at increased genetic risk for Alzheimer disease.
doi:10.1001/2013.jamaneurol.286
PMCID: PMC3745014  PMID: 23599929
19.  Association between an Alzheimer’s Disease-Related Index and APOE ε4 Gene Dose 
PLoS ONE  2013;8(6):e67163.
Background
We introduced a hypometabolic convergence index (HCI) to characterize in a single measurement the extent to which a person’s fluorodeoxyglucose positron emission tomogram (FDG PET) corresponds to that in Alzheimer’s disease (AD). Apolipoprotein E ε4 (APOE ε4) gene dose is associated with three levels of risk for late-onset AD. We explored the association between gene dose and HCI in cognitively normal ε4 homozygotes, heterozygotes, and non-carriers.
Methods
An algorithm was used to characterize and compare AD-related HCIs in cognitively normal individuals, including 36 ε4 homozygotes, 46 heterozygotes, and 78 non-carriers.
Results
These three groups differed significantly in their HCIs (ANOVA, p = 0.004), and there was a significant association between HCIs and gene dose (linear trend, p = 0.001).
Conclusions
The HCI is associated with three levels of genetic risk for late-onset AD. This supports the possibility of using a single FDG PET measurement to help in the preclinical detection and tracking of AD.
doi:10.1371/journal.pone.0067163
PMCID: PMC3694066  PMID: 23840615
20.  Correlations between FDG PET glucose uptake-MRI gray matter volume scores and apolipoprotein E ε4 gene dose in cognitively normal adults: a cross-validation study using voxel-based multi-modal partial least squares 
Neuroimage  2012;60(4):2316-2322.
We previously introduced a voxel-based, multi-modal application of the partial least square algorithm (MMPLS) to characterize the linkage between patterns in a person’s complementary complex datasets without the need to correct for multiple regional comparisons. Here we used it to demonstrate a strong correlation between MMPLS scores to characterize the linkage between the covarying patterns of fluorodeoxyglucose positron emission tomography (FDG PET) measurements of regional glucose metabolism and magnetic resonance imaging (MRI) measurements of regional gray matter associated with apolipoprotein E (APOE) ε4 gene dose (i.e., three levels of genetic risk for late-onset Alzheimer’s disease (AD)) in cognitively normal, late-middle-aged persons. Coregistered and spatially normalized FDG PET and MRI images from 70% of the subjects (27 ε4 homozygotes, 36 ε4 heterozygotes and 67 ε4 non-carriers) were used in a hypothesis-generating MMPLS analysis to characterize the covarying pattern of regional gray matter volume and cerebral glucose metabolism most strongly correlated with APOE-ε4 gene dose. Coregistered and spatially normalized FDG PET and MRI images from the remaining 30% of the subjects were used in a hypothesis-testing MMPLS analysis to generate FDG PET-MRI gray matter MMPLS scores blind to their APOE genotype and characterize their relationship to APOE-ε4 gene dose. The hypothesis-generating analysis revealed covarying regional gray matter volume and cerebral glucose metabolism patterns that resembled those in traditional univariate analyses of AD and APOE-ε4 gene dose and PET-MRI scores that were strongly correlated with APOE-ε4 gene dose (p<1×10−16). The hypothesis-testing analysis results showed strong correlations between FDG PET-MRI gray matter scores and APOE-ε4 gene dose (p=8.7×10−4). Our findings support the possibility of using the MMPLS to analyze complementary datasets from the same person in the presymptomatic detection and tracking of AD.
doi:10.1016/j.neuroimage.2012.02.005
PMCID: PMC3325642  PMID: 22348880
21.  Predicting missing biomarker data in a longitudinal study of Alzheimer disease 
Lo, Raymond Y. | Jagust, William J. | Aisen, Paul | Jack, Clifford R. | Toga, Arthur W. | Beckett, Laurel | Gamst, Anthony | Soares, Holly | C. Green, Robert | Montine, Tom | Thomas, Ronald G. | Donohue, Michael | Walter, Sarah | Dale, Anders | Bernstein, Matthew | Felmlee, Joel | Fox, Nick | Thompson, Paul | Schuff, Norbert | Alexander, Gene | DeCarli, Charles | Bandy, Dan | Chen, Kewei | Morris, John | Lee, Virginia M.-Y. | Korecka, Magdalena | Crawford, Karen | Neu, Scott | Harvey, Danielle | Kornak, John | Saykin, Andrew J. | Foroud, Tatiana M. | Potkin, Steven | Shen, Li | Buckholtz, Neil | Kaye, Jeffrey | Dolen, Sara | Quinn, Joseph | Schneider, Lon | Pawluczyk, Sonia | Spann, Bryan M. | Brewer, James | Vanderswag, Helen | Heidebrink, Judith L. | Lord, Joanne L. | Petersen, Ronald | Johnson, Kris | Doody, Rachelle S. | Villanueva-Meyer, Javier | Chowdhury, Munir | Stern, Yaakov | Honig, Lawrence S. | Bell, Karen L. | Morris, John C. | Mintun, Mark A. | Schneider, Stacy | Marson, Daniel | Griffith, Randall | Clark, David | Grossman, Hillel | Tang, Cheuk | Marzloff, George | Toledo-Morrell, Leylade | Shah, Raj C. | Duara, Ranjan | Varon, Daniel | Roberts, Peggy | Albert, Marilyn S. | Pedroso, Julia | Toroney, Jaimie | Rusinek, Henry | de Leon, Mony J | De Santi, Susan M | Doraiswamy, P. Murali | Petrella, Jeffrey R. | Aiello, Marilyn | Clark, Christopher M. | Pham, Cassie | Nunez, Jessica | Smith, Charles D. | Given, Curtis A. | Hardy, Peter | Lopez, Oscar L. | Oakley, MaryAnn | Simpson, Donna M. | Ismail, M. Saleem | Brand, Connie | Richard, Jennifer | Mulnard, Ruth A. | Thai, Gaby | Mc-Adams-Ortiz, Catherine | Diaz-Arrastia, Ramon | Martin-Cook, Kristen | DeVous, Michael | Levey, Allan I. | Lah, James J. | Cellar, Janet S. | Burns, Jeffrey M. | Anderson, Heather S. | Laubinger, Mary M. | Bartzokis, George | Silverman, Daniel H.S. | Lu, Po H. | Graff-Radford MBBCH, Neill R | Parfitt, Francine | Johnson, Heather | Farlow, Martin | Herring, Scott | Hake, Ann M. | van Dyck, Christopher H. | MacAvoy, Martha G. | Benincasa, Amanda L. | Chertkow, Howard | Bergman, Howard | Hosein, Chris | Black, Sandra | Graham, Simon | Caldwell, Curtis | Hsiung, Ging-Yuek Robin | Feldman, Howard | Assaly, Michele | Kertesz, Andrew | Rogers, John | Trost, Dick | Bernick, Charles | Munic, Donna | Wu, Chuang-Kuo | Johnson, Nancy | Mesulam, Marsel | Sadowsky, Carl | Martinez, Walter | Villena, Teresa | Turner, Scott | Johnson, Kathleen B. | Behan, Kelly E. | Sperling, Reisa A. | Rentz, Dorene M. | Johnson, Keith A. | Rosen, Allyson | Tinklenberg, Jared | Ashford, Wes | Sabbagh, Marwan | Connor, Donald | Jacobson, Sandra | Killiany, Ronald | Norbash, Alexander | Nair, Anil | Obisesan, Thomas O. | Jayam-Trouth, Annapurni | Wang, Paul | Lerner, Alan | Hudson, Leon | Ogrocki, Paula | DeCarli, Charles | Fletcher, Evan | Carmichael, Owen | Kittur, Smita | Mirje, Seema | Borrie, Michael | Lee, T-Y | Bartha, Dr Rob | Johnson, Sterling | Asthana, Sanjay | Carlsson, Cynthia M. | Potkin, Steven G. | Preda, Adrian | Nguyen, Dana | Tariot, Pierre | Fleisher, Adam | Reeder, Stephanie | Bates, Vernice | Capote, Horacio | Rainka, Michelle | Hendin, Barry A. | Scharre, Douglas W. | Kataki, Maria | Zimmerman, Earl A. | Celmins, Dzintra | Brown, Alice D. | Gandy, Sam | Marenberg, Marjorie E. | Rovner, Barry W. | Pearlson, Godfrey | Anderson, Karen | Saykin, Andrew J. | Santulli, Robert B. | Englert, Jessica | Williamson, Jeff D. | Sink, Kaycee M. | Watkins, Franklin | Ott, Brian R. | Wu, Chuang-Kuo | Cohen, Ronald | Salloway, Stephen | Malloy, Paul | Correia, Stephen | Rosen, Howard J. | Miller, Bruce L. | Mintzer, Jacobo
Neurology  2012;78(18):1376-1382.
Objective:
To investigate predictors of missing data in a longitudinal study of Alzheimer disease (AD).
Methods:
The Alzheimer's Disease Neuroimaging Initiative (ADNI) is a clinic-based, multicenter, longitudinal study with blood, CSF, PET, and MRI scans repeatedly measured in 229 participants with normal cognition (NC), 397 with mild cognitive impairment (MCI), and 193 with mild AD during 2005–2007. We used univariate and multivariable logistic regression models to examine the associations between baseline demographic/clinical features and loss of biomarker follow-ups in ADNI.
Results:
CSF studies tended to recruit and retain patients with MCI with more AD-like features, including lower levels of baseline CSF Aβ42. Depression was the major predictor for MCI dropouts, while family history of AD kept more patients with AD enrolled in PET and MRI studies. Poor cognitive performance was associated with loss of follow-up in most biomarker studies, even among NC participants. The presence of vascular risk factors seemed more critical than cognitive function for predicting dropouts in AD.
Conclusion:
The missing data are not missing completely at random in ADNI and likely conditional on certain features in addition to cognitive function. Missing data predictors vary across biomarkers and even MCI and AD groups do not share the same missing data pattern. Understanding the missing data structure may help in the design of future longitudinal studies and clinical trials in AD.
doi:10.1212/WNL.0b013e318253d5b3
PMCID: PMC3345787  PMID: 22491869
22.  Blood pressure is associated with higher brain amyloid burden and lower glucose metabolism in healthy late middle-age persons 
Neurobiology of Aging  2011;33(4):827.e11-827.e19.
Epidemiological studies suggest that elevated blood pressure (BP) in mid-life is associated with increased risk of Alzheimer’s disease (AD) in late-life. In this preliminary study, we investigated the extent to which BP measurements are related to positron emission tomography (PET) measurements of fibrillar amyloid-beta burden using Pittsburgh Compound-B (PiB) and fluorodeoxyglucose (FDG) PET measures of cerebral metabolic rate for glucose metabolism (CMRgl) in cognitively normal, late-middle-aged to older adult apolipoprotein E (APOE) ε4 homozygotes, heterozygotes and non-carriers. PiB PET results revealed that systolic BP (SBP) and pulse pressure (PP) were each positively correlated with cerebral-to-cerebellar PiB distribution volume ratio (DVR) in frontal, temporal and posterior-cingulate/precuneus regions, whereas no significant positive correlations were found between PiB DVRs and diastolic BP (DBP). FDG PET results revealed significant inverse correlations between each of the BP measures and lower CMRgl in frontal and temporal brain regions. These preliminary findings provide additional evidence that higher BP, likely a reflection of arterial stiffness, during late-mid-life may be associated with increased risk of presymptomatic AD.
doi:10.1016/j.neurobiolaging.2011.06.020
PMCID: PMC3236809  PMID: 21821316
APOE; blood pressure; arterial stiffness; brain imaging; PET; Alzheimer’s disease; amyloid; PiB; Pittsburgh Compound-B
23.  Altered Default Mode Network Connectivity in Alzheimer’s Disease--A Resting Functional MRI and Bayesian Network Study 
Human brain mapping  2011;32(11):1868-1881.
A number of functional magnetic resonance imaging (fMRI) studies reported the existence of default mode network (DMN) and its disruption due to the presence of a disease such as Alzheimer’s disease (AD). In this current investigation, firstly, we used the independent component analysis (ICA) technique to confirm the DMN difference between patients with AD and normal control (NC) reported in previous studies. Consistent with previous studies, the decreased resting-state functional connectivity of DMN in AD was identified in posterior cingulated cortex (PCC), medial prefrontal cortex (MPFC), inferior parietal cortex (IPC), inferior temporal cortex (ITC) and hippocampus (HC). Moreover, we introduced Bayesian Network (BN) to study the effective connectivity of DMN and the difference between AD and NC. Compared the DMN effective connectivity in AD to the one in NC using a non-parametric random permutation test, we found that connections from left HC to left IPC, left ITC to right HC, right HC to left IPC, to MPFC and to PCC were all lost. In addition, in AD group, the connection directions between right HC and left HC, between left HC and left ITC, and between right IPC and right ITC were opposite to those in NC group. The connections of right HC to other regions, except left HC, within the BN were all statistically in-distinguishable from 0, suggesting an increased right hippocampal pathological and functional burden in AD. The altered effective connectivity in patients with AD may reveal more characteristics of the disease and may serve as a potential biomarker.
doi:10.1002/hbm.21153
PMCID: PMC3208821  PMID: 21259382
biomarker; effective connectivity; functional connectivity; resting state; fMRI
24.  Positron Emission Tomography and Neuropathologic Estimates of Fibrillar Amyloid-β in a Patient With Down Syndrome and Alzheimer Disease 
Archives of Neurology  2011;68(11):1461-1466.
Background
Down syndrome appears to be associated with a virtually certain risk of fibrillar amyloid-β (Aβ) pathology by the age of 40 and a very high risk of dementia at older ages. The positron emission tomography (PET) ligand florbetapir F18 has been shown to characterize fibrillar Aβ in the living human brain and to provide a close correlation with subsequent Aβ neuropathology in individuals proximate to and after the end of life. The extent to which the most frequently used PET ligands can be used to detect fibrillar Aβ in patients with Down syndrome remains to be determined.
Objectives
To characterize PET estimates of fibrillar Aβ burden in a Down syndrome patient very close to the end of life and to compare them with neuropathologic assessment made after his death.
Design/Methods
With the family’s informed consent, florbetapir PET was used to study a 55-year-old Down syndrome patient with Alzheimer disease near the end of life; his brain was donated for neuropathologic assessment when he died 14 days later. Visual ratings of cerebral florbetapir uptake were performed by trained readers who were masked to the patient’s diagnosis as part of a larger study, and an automated algorithm was used to characterize regional-to-cerebellar standard uptake value ratios in 6 cerebral regions of interest. Neuropathologic assessments were performed masked to the patient’s diagnosis or PET measurements.
Results
Visual ratings and automated analyses of the PET image revealed a heavy fibrillar Aβ burden in cortical, striatal, and thalamic regions, similar to that reported for patients with late-onset Alzheimer disease. This matched neuropathologic findings of frequent neuritic and diffuse plaques, as well as frequent amyloid angiopathy, except for neuropathologically demonstrated frequent cerebellar diffuse plaques and amyloid angiopathy that were not detected by the PET scan.
Conclusions
Florbetapir PET can be used to detect increased cerebral-to-cerebellar fibrillar Aβ burden in a Down syndrome patient with Alzheimer disease, even in the presence of frequent amyloid angiopathy and diffuse plaques in the cerebellum. Additional studies are needed to determine the extent to which PET could be used to detect and to track fibrillar Aβ and to evaluate investigational Aβ-modifying treatments in the presymptomatic and symptomatic stages of Alzheimer disease.
doi:10.1001/archneurol.2011.535
PMCID: PMC3346179  PMID: 22084131

Results 1-25 (47)