Petersen, Ronald C.

AbstractIntroductionWe conducted Japanese Alzheimer's Disease Neuroimaging Initiative (J‐ADNI) and compared the basic characteristics and progression profiles with those of ADNI in North America.MethodsA total of 537 Japanese subjects with normal cognition, late amnestic mild cognitive impairment (LMCI), or mild Alzheimer's disease (AD) were enrolled using the same criteria as ADNI. Rates of changes in representative cognitive or functional measures were compared for amyloid positron emission tomography‐ or cerebrospinal fluid amyloid β(1–42)‐positive LMCI and mild AD between J‐ADNI and ADNI.ResultsAmyloid positivity rates were significantly higher in normal cognition of ADNI but at similar levels in LMCI and mild AD between J‐ADNI and ADNI. Profiles of decline in cognitive or functional measures in amyloid‐positive LMCI in J‐ADNI (n = 75) and ADNI (n = 269) were remarkably similar, whereas those in mild AD were milder in J‐ADNI (n = 73) compared with ADNI (n = 230).DiscussionThese results support the feasibility of bridging of clinical trials in the prodromal stage of AD between Asia and western countries.

AbstractThe Alzheimer's Association's Research Roundtable met in November 2017 to explore the new National Institute on Aging and the Alzheimer's Association Research Framework for Alzheimer's disease. The meeting allowed experts in the field from academia, industry, and government to provide perspectives on the new National Institute on Aging and the Alzheimer's Association Research Framework. This review will summarize the “A, T, N System” (Amyloid, Tau, and Neurodegeneration) using biomarkers and how this may be applied to clinical research and drug development. In addition, challenges and barriers to the potential adoption of this new framework will be discussed. Finally, future directions for research will be proposed.

AbstractIntroductionWe examined and compared plasma phospho‐tau181 (pTau181) and total tau: (1) across the Alzheimer's disease (AD) clinical spectrum; (2) in relation to brain amyloid β (Aβ) positron emission tomography (PET), tau PET, and cortical thickness; and (3) as a screening tool for elevated brain Aβ.MethodsParticipants included 172 cognitively unimpaired, 57 mild cognitively impaired, and 40 AD dementia patients with concurrent Aβ PET (Pittsburgh compound B), tau PET (AV1451), magnetic resonance imaging, plasma total tau, and pTau181.ResultsPlasma total tau and pTau181 levels were higher in AD dementia patients than those in cognitively unimpaired. Plasma pTau181 was more strongly associated with both Aβ and tau PET. Plasma pTau181 was a more sensitive and specific predictor of elevated brain Aβ than total tau and was as good as, or better than, the combination of age and apolipoprotein E (APOE).DiscussionPlasma pTau181 may have utility as a biomarker of AD pathophysiology and as a noninvasive screener for elevated brain Aβ.

Abstract Introduction Neuroimaging modalities can measure different aspects of the disease process in Alzheimer's disease, although the relationship between these modalities is unclear. Methods We assessed subject‐level regional correlations between tau on [ 18 F]AV‐1451 positron emission tomography (PET), β amyloid on Pittsburgh compound B PET, hypometabolism on [ 18 F] fluorodeoxyglucose PET, and cortical thickness on magnetic resonance imaging in 96 participants with typical and atypical Alzheimer's disease presentations. We also assessed how correlations between modalities varied according to age, presenting syndrome, tau‐PET severity, and asymmetry. Results [ 18 F]AV‐1451 uptake showed the strongest regional correlation with hypometabolism. Correlations between [ 18 F]AV‐1451 uptake and both hypometabolism and cortical thickness were stronger in participants with greater cortical tau severity. In addition, age, tau asymmetry, and clinical diagnosis influenced the strength of the correlation between [ 18 F]AV‐1451 uptake and cortical thickness. Discussion These findings support a close relationship between tau and hypometabolism in Alzheimer's disease but show that correlations between neuroimaging modalities vary across participants.

ObjectivesTo assess [18F]AV‐1451 tau‐PET (positron emission tomography) uptake patterns across the primary progressive aphasia (PPA) variants (logopenic, semantic, and agrammatic), examine regional uptake patterns of [18F]AV‐1451 independent of clinical diagnosis, and compare the diagnostic utility of [18F]AV‐1451, [18F]‐fluorodeoxygluclose (FDG)‐PET and MRI (magnetic resonance imaging) to differentiate the PPA variants.MethodsWe performed statistical parametric mapping of [18F]AV‐1451 across 40 PPA patients (logopenic‐PPA = 14, semantic‐PPA = 13, and agrammatic‐PPA = 13) compared to 80 cognitively normal, Pittsburgh compound B–negative controls, age and gender matched 2:1. Principal component analysis of regional [18F]AV‐1451 tau‐PET standard uptake value ratio was performed to understand underlying patterns of [18F]AV‐1451 uptake independent of clinical diagnosis. Penalized multinomial regression analyses were utilized to assess diagnostic utility.ResultsLogopenic‐PPA showed striking uptake throughout neocortex, particularly temporoparietal, compared to controls, semantic‐PPA, and agrammatic‐PPA. Semantic‐PPA and agrammatic‐PPA showed milder patterns of focal [18F]AV‐1451 uptake. Semantic‐PPA showed elevated uptake (left>right) in anteromedial temporal lobes, compared to controls and agrammatic‐PPA. Agrammatic‐PPA showed elevated uptake (left>right) throughout prefrontal white matter and in subcortical gray matter structures, compared to controls and semantic‐PPA. The principal component analysis of regional [18F]AV‐1451 indicated two primary dimensions, a severity dimension that distinguished logopenic‐PPA from agrammatic‐PPA and semantic‐PPA, and a frontal versus temporal contrast that distinguishes agrammatic‐PPA and semantic‐PPA cases. Diagnostic utility of [18F]AV‐1451was superior to MRI and at least equal to FDG‐PET.Interpretation[18F]AV‐1451binding characteristics differ across the PPA variants and were excellent at distinguishing between the variants. [18F]AV‐1451binding characteristics were as good or better than other brain imaging modalities utilized in clinical practice, suggesting that [18F]AV‐1451 may have clinical diagnostic utility in PPA. Ann Neurol 2018 Ann Neurol 2018;83:599–611