Petersen, Ronald C.

BackgroundRecently, a novel mutation in exon 24 of DNAJC13 gene (p.Asn855Ser, rs387907571) has been reported to cause autosomal dominant Parkinson's disease (PD) in a multi‐incident Mennonite family.MethodsIn the present study the mutation containing exon of the DNAJC13 gene has been sequenced in a Caucasian series consisting of 1938 patients with clinical PD and 838 with pathologically diagnosed Lewy body disease (LBD).ResultsOur sequence analysis did not identify any coding variants in exon 24 of DNAJC13. Two previously described variants in intron 23 (rs200204728 and rs2369796) were observed.ConclusionOur results indicate that the region surrounding the DNAJC13 p.Asn855Ser substitution is highly conserved and mutations in this exon are not a common cause of PD or LBD among Caucasian populations.

ObjectiveThe aim of this study was to determine whether the frequency of TAR DNA‐binding protein 43 (TDP‐43) deposition in Alzheimer's disease (AD) differs across pathologically defined AD subtypes (hippocampal sparing [HpSp]; typical and limbic) and further examine the relationship between TDP‐43, pathological subtype, and clinical features in AD.MethodsWe identified all cases with pathologically confirmed AD (NIA‐Reagan intermediate‐high probability, Braak stage IV–VI) independent of cognitive status (n = 188). Neurofibrillary tangle counts were performed using thioflavin‐S microscopy in hippocampus and three neocortical regions, and all cases were subtyped: HpSp AD pathology (n = 19); typical AD pathology (n = 136); and limbic AD pathology (n = 33). TDP‐43 immunoreactivity was performed in multiple brain regions to assess for the presence of TDP‐43 and TDP‐43 stage. All cases were clinically subclassified at presentation as amnestic AD dementia versus atypical AD dementia. Statistical analysis was performed using linear and penalized logistic regression to assess associations with pathological subtype, and the effects of TDP‐43, accounting for possible interactions between pathological subtype and TDP‐43.ResultsTDP‐43 deposition was frequent in typical (59%) and limbic AD pathologies (67%), but not HpSp AD pathology (21%; p = 0.003). The observed associations of TDP‐43 with greater memory loss, naming and functional decline, and smaller hippocampal volumes, closest to death, did not differ across AD pathological subtype. Clinical presentation was associated with pathological subtype (p = 0.01), but not TDP‐43 (p = 0.69).InterpretationAlthough the frequency of TDP‐43 deposition in AD varies by pathological subtype, the observed effects of TDP‐43 on clinical/magnetic resonance imaging features are consistent across pathological subtypes. Clinical presentation in AD is driven by pathological subtype, not by TDP‐43. Ann Neurol 2015;78:Ann Neurol 2015;78:679–696

AbstractIntroductionWe describe Alzheimer's Disease Neuroimaging Initiative (ADNI) Biomarker Core progress including: the Biobank; cerebrospinal fluid (CSF) amyloid beta (Aβ1–42), t‐tau, and p‐tau181 analytical performance, definition of Alzheimer's disease (AD) profile for plaque, and tangle burden detection and increased risk for progression to AD; AD disease heterogeneity; progress in standardization; and new studies using ADNI biofluids.MethodsReview publications authored or coauthored by ADNI Biomarker core faculty and selected non‐ADNI studies to deepen the understanding and interpretation of CSF Aβ1–42, t‐tau, and p‐tau181 data.ResultsCSF AD biomarker measurements with the qualified AlzBio3 immunoassay detects neuropathologic AD hallmarks in preclinical and prodromal disease stages, based on CSF studies in non‐ADNI living subjects followed by the autopsy confirmation of AD. Collaboration across ADNI cores generated the temporal ordering model of AD biomarkers varying across individuals because of genetic/environmental factors that increase/decrease resilience to AD pathologies.DiscussionFurther studies will refine this model and enable the use of biomarkers studied in ADNI clinically and in disease‐modifying therapeutic trials.

AbstractIntroductionThis article reviews the current status of the Clinical Core of the Alzheimer's Disease Neuroimaging Initiative (ADNI), and summarizes planning for the next stage of the project.MethodsClinical Core activities and plans were synthesized based on discussions among the Core leaders and external advisors.ResultsThe longitudinal data in ADNI‐2 provide natural history data on a clinical trials population and continue to inform refinement and standardization of assessments, models of trajectories, and clinical trial methods that have been extended into sporadic preclinical Alzheimer's disease (AD).DiscussionPlans for the next phase of the ADNI project include maintaining longitudinal follow‐up of the normal and mild cognitive impairment cohorts, augmenting specific clinical cohorts, and incorporating novel computerized cognitive assessments and patient‐reported outcomes. A major hypothesis is that AD represents a gradually progressive disease that can be identified precisely in its long presymptomatic phase, during which intervention with potentially disease‐modifying agents may be most useful.

Abstract Introduction The Alzheimer's Disease Neuroimaging Initiative (ADNI) was established in 2004 to facilitate the development of effective treatments for Alzheimer's disease (AD) by validating biomarkers for AD clinical trials. Methods We searched for ADNI publications using established methods. Results ADNI has (1) developed standardized biomarkers for use in clinical trial subject selection and as surrogate outcome measures; (2) standardized protocols for use across multiple centers; (3) initiated worldwide ADNI; (4) inspired initiatives investigating traumatic brain injury and post‐traumatic stress disorder in military populations, and depression, respectively, as an AD risk factor; (5) acted as a data‐sharing model; (6) generated data used in over 600 publications, leading to the identification of novel AD risk alleles, and an understanding of the relationship between biomarkers and AD progression; and (7) inspired other public‐private partnerships developing biomarkers for Parkinson's disease and multiple sclerosis. Discussion ADNI has made myriad impacts in its first decade. A competitive renewal of the project in 2015 would see the use of newly developed tau imaging ligands, and the continued development of recruitment strategies and outcome measures for clinical trials.

Abstract The Alzheimer's Disease Neuroimaging Initiative (ADNI) is an ongoing, longitudinal, multicenter study designed to develop clinical, imaging, genetic, and biochemical biomarkers for the early detection and tracking of Alzheimer's disease (AD). The initial study, ADNI‐1, enrolled 400 subjects with early mild cognitive impairment (MCI), 200 with early AD, and 200 cognitively normal elderly controls. ADNI‐1 was extended by a 2‐year Grand Opportunities grant in 2009 and by a competitive renewal, ADNI‐2, which enrolled an additional 550 participants and will run until 2015. This article reviews all papers published since the inception of the initiative and summarizes the results to the end of 2013. The major accomplishments of ADNI have been as follows: (1) the development of standardized methods for clinical tests, magnetic resonance imaging (MRI), positron emission tomography (PET), and cerebrospinal fluid (CSF) biomarkers in a multicenter setting; (2) elucidation of the patterns and rates of change of imaging and CSF biomarker measurements in control subjects, MCI patients, and AD patients. CSF biomarkers are largely consistent with disease trajectories predicted by β‐amyloid cascade (Hardy, J Alzheimer's Dis 2006;9(Suppl 3):151–3) and tau‐mediated neurodegeneration hypotheses for AD, whereas brain atrophy and hypometabolism levels show predicted patterns but exhibit differing rates of change depending on region and disease severity; (3) the assessment of alternative methods of diagnostic categorization. Currently, the best classifiers select and combine optimum features from multiple modalities, including MRI, [ 18 F]‐fluorodeoxyglucose‐PET, amyloid PET, CSF biomarkers, and clinical tests; (4) the development of blood biomarkers for AD as potentially noninvasive and low‐cost alternatives to CSF biomarkers for AD diagnosis and the assessment of α‐syn as an additional biomarker; (5) the development of methods for the early detection of AD. CSF biomarkers, β‐amyloid 42 and tau, as well as amyloid PET may reflect the earliest steps in AD pathology in mildly symptomatic or even nonsymptomatic subjects and are leading candidates for the detection of AD in its preclinical stages; (6) the improvement of clinical trial efficiency through the identification of subjects most likely to undergo imminent future clinical decline and the use of more sensitive outcome measures to reduce sample sizes. Multimodal methods incorporating APOE status and longitudinal MRI proved most highly predictive of future decline. Refinements of clinical tests used as outcome measures such as clinical dementia rating‐sum of boxes further reduced sample sizes; (7) the pioneering of genome‐wide association studies that leverage quantitative imaging and biomarker phenotypes, including longitudinal data, to confirm recently identified loci, CR1, CLU , and PICALM and to identify novel AD risk loci; (8) worldwide impact through the establishment of ADNI‐like programs in Japan, Australia, Argentina, Taiwan, China, Korea, Europe, and Italy; (9) understanding the biology and pathobiology of normal aging, MCI, and AD through integration of ADNI biomarker and clinical data to stimulate research that will resolve controversies about competing hypotheses on the etiopathogenesis of AD, thereby advancing efforts to find disease‐modifying drugs for AD; and (10) the establishment of infrastructure to allow sharing of all raw and processed data without embargo to interested scientific investigators throughout the world.

AbstractTranscription factors that mediate neuronal defenses against diverse stresses were quantified in plasma neural‐derived exosomes of Alzheimer's disease or frontotemporal dementia patients and matched controls. Exosomal levels of low‐density lipoprotein receptor‐related protein 6, heat‐shock factor‐1, and repressor element 1‐silencing transcription factor all were significantly lower in Alzheimer's disease patients than controls (P < 0.0001). In frontotemporal dementia, the only significant difference was higher levels of repressor element 1‐silencing transcription factor than in controls. Exosomal transcription factors were diminished 2–10 years before clinical diagnosis of Alzheimer's disease. Low exosomal levels of survival proteins may explain decreased neuronal resistance to Alzheimer's disease neurotoxic proteins.

Abstract Introduction This study assessed apolipoprotein E ( APOE ) ε4 carrier status effects on Alzheimer's disease imaging and cerebrospinal fluid (CSF) biomarkers in cognitively normal older adults with significant memory concerns (SMC). Methods Cognitively normal, SMC, and early mild cognitive impairment participants from Alzheimer's Disease Neuroimaging Initiative were divided by APOE ε4 carrier status. Diagnostic and APOE effects were evaluated with emphasis on SMC. Additional analyses in SMC evaluated the effect of the interaction between APOE and [ 18 F]Florbetapir amyloid positivity on CSF biomarkers. Results SMC ε4+ showed greater amyloid deposition than SMC ε4−, but no hypometabolism or medial temporal lobe (MTL) atrophy. SMC ε4+ showed lower amyloid beta 1–42 and higher tau/p‐tau than ε4−, which was most abnormal in APOE ε4+ and cerebral amyloid positive SMC. Discussion SMC APOE ε4+ show abnormal changes in amyloid and tau biomarkers, but no hypometabolism or MTL neurodegeneration, reflecting the at‐risk nature of the SMC group and the importance of APOE in mediating this risk.