Citations

ABSTRACTBACKGROUND AND PURPOSEMild cognitive impairment (MCI) precedes both Alzheimer's disease (AD) dementia and with Lewy bodies (DLB). We investigated proton magnetic resonance spectroscopy (MRS) characteristics of MCI patients who progressed to DLB compared to those who progressed to AD dementia or remained stable.METHODSConsecutive MCI patients who underwent single voxel MRS at baseline and progressed to DLB (n = 10) were identified during a median follow‐up period of 18 months. From the same cohort, we identified age‐ and sex‐matched MCI patients who progressed to AD dementia (n = 27) or remained stable (n = 20) during a similar follow‐up period. This study was approved by the Institutional Review Board and informed consent was from every subject.RESULTSMCI patients who progressed to AD dementia were characterized by lower N‐acetylaspartate (NAA)/Cr ratio in the posterior cingulate voxel compared to those who progressed to DLB (P = .001). Decreased NAA/Cr in the posterior cingulate voxel differentiated MCI patients who progressed to DLB from those who progressed to AD with an area under the receiver operating characteristic curve of .85 (P < .001) on logistic regression analysis.CONCLUSIONSMRS may be useful in differentiating MCI patients with prodromal AD dementia from those with prodromal DLB for early disease‐specific interventions.

AbstractBackgroundLow HCV has recently been qualified by the European Medicines Agency as a biomarker for enrichment of clinical trials in predementia stages of Alzheimer's disease. For automated methods to meet the necessary regulatory requirements, it is essential they be standardized and their performance be well characterized.MethodsThe within‐image and between‐field strength reproducibility of automated hippocampal volumetry using the Learning Embeddings for Atlas Propagation (or LEAP) algorithm was assessed on 153 Alzheimer's Disease Neuroimaging Initiative subjects.ResultsTests/retests at 1.5 T and 3 T, and a comparison between 1.5 T and 3 T, yielded average unsigned variabilities in HCVs of 1.51%, 1.52%, and 2.68%. A small bias between field strengths (mean signed difference, 1.17%; standard deviation, 3.07%) was observed.ConclusionsThe measured reproducibility characteristics confirm the suitability of using automated magnetic resonance imaging analyses to assess HCVs quantitatively and to represent a fundamental characterization that is critical to meet the regulatory requirements for using hippocampal volumetry in clinical trials and health care.

AbstractBackgroundRegulatory qualification of a biomarker for a defined context of use provides scientifically robust assurances to sponsors and regulators that accelerate appropriate adoption of biomarkers into drug development.MethodsThe Coalition Against Major Diseases submitted a dossier to the Scientific Advice Working Party of the European Medicines Agency requesting a qualification opinion on the use of hippocampal volume as a biomarker for enriching clinical trials in subjects with mild cognitive impairment, incorporating a scientific rationale, a literature review and a de novo analysis of Alzheimer's Disease Neuroimaging Initiative data.ResultsThe literature review and de novo analysis were consistent with the proposed context of use, and the Committee for Medicinal Products for Human Use released an opinion in November 2011.ConclusionsWe summarize the scientific rationale and the data that supported the first qualification of an imaging biomarker by the European Medicines Agency.

AbstractBackgroundApolipoprotein E ε4 (APOE ε4) is a risk factor for β‐amyloid deposition in Alzheimer's disease dementia. Its influence on β‐amyloid deposition in speech and language disorders, including primary progressive aphasia (PPA), is unclear.MethodsOne hundred thirty subjects with PPA or progressive speech apraxia underwent APOE genotyping and Pittsburgh compound B (PiB) PET scanning. The relationship between APOE ε4 and PiB status, as well as severity and regional distribution of PiB, was assessed.ResultsForty‐five subjects had an APOE ε4 allele and 60 subjects were PiB‐positive. The odds ratio for a subject with APOE ε4 being PiB‐positive compared with a subject without APOE ε4 being PiB‐positive was 10.2 (95% confidence interval, 4.4–25.5; P < .0001). The APOE ε4 allele did not influence regional PiB distribution or severity.ConclusionAPOE ε4 increases the risk of β‐amyloid deposition in PPA and progressive speech apraxia but does not influence regional β‐amyloid distribution or severity.

AbstractBoth traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD) are common problems resulting from military service, and both have been associated with increased risk of cognitive decline and dementia resulting from Alzheimer's disease (AD) or other causes. This study aims to use imaging techniques and biomarker analysis to determine whether traumatic brain injury (TBI) and/or PTSD resulting from combat or other traumas increase the risk for AD and decrease cognitive reserve in Veteran subjects, after accounting for age. Using military and Department of Veterans Affairs records, 65 Vietnam War veterans with a history of moderate or severe TBI with or without PTSD, 65 with ongoing PTSD without TBI, and 65 control subjects are being enrolled in this study at 19 sites. The study aims to select subject groups that are comparable in age, gender, ethnicity, and education. Subjects with mild cognitive impairment (MCI) or dementia are being excluded. However, a new study just beginning, and similar in size, will study subjects with TBI, subjects with PTSD, and control subjects with MCI. Baseline measurements of cognition, function, blood, and cerebrospinal fluid biomarkers; magnetic resonance images (structural, diffusion tensor, and resting state blood‐level oxygen dependent (BOLD) functional magnetic resonance imaging); and amyloid positron emission tomographic (PET) images with florbetapir are being obtained. One‐year follow‐up measurements will be collected for most of the baseline procedures, with the exception of the lumbar puncture, the PET imaging, and apolipoprotein E genotyping. To date, 19 subjects with TBI only, 46 with PTSD only, and 15 with TBI and PTSD have been recruited and referred to 13 clinics to undergo the study protocol. It is expected that cohorts will be fully recruited by October 2014. This study is a first step toward the design and statistical powering of an AD prevention trial using at‐risk veterans as subjects, and provides the basis for a larger, more comprehensive study of dementia risk factors in veterans.