title: The Alzheimer's Disease Neuroimaging Initiative phase 2: Increasing the length, breadth, and depth of our understanding.
abstract: BACKGROUND
  The Alzheimer's Disease Neuroimaging Initiative (ADNI) is a multisite study designed to characterize the trajectories of biomarkers across the aging process. We present ADNI Biostatistics Core analyses that integrate data over the length, breadth, and depth of ADNI.
  
  
  METHODS
  Relative progression of key imaging, fluid, and clinical measures was assessed. Individuals with subjective memory complaints (SMC) and early mild cognitive impairment (eMCI) were compared with normal controls (NC), MCI, and individuals with Alzheimer's disease. Amyloid imaging and magnetic resonance imaging (MRI) summaries were assessed as predictors of disease progression.
  
  
  RESULTS
  Relative progression of markers supports parts of the amyloid cascade hypothesis, although evidence of earlier occurrence of cognitive change exists. SMC are similar to NC, whereas eMCI fall between the cognitively normal and MCI groups. Amyloid leads to faster conversion and increased cognitive impairment.
  
  
  CONCLUSIONS
  Analyses support features of the amyloid hypothesis, but also illustrate the considerable heterogeneity in the aging process.
authors.affiliation: Division of Biostatistics, Department of Public Health Sciences, University of California, Davis, CA, USA. Electronic address: labeckett@ucdavis.edu.
authors.forename: Laurel A
authors.initials: LA
authors.lastname: Beckett
authors.affiliation: Division of Biostatistics and Bioinformatics, Department of Family Medicine and Public Health, University of California, San Diego, CA, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Donohue
authors.affiliation: Division of Biostatistics, Department of Public Health Sciences, University of California, Davis, CA, USA.
authors.forename: Cathy
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Neurosciences, University of California, San Diego, CA, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Aisen
authors.affiliation: Division of Biostatistics, Department of Public Health Sciences, University of California, Davis, CA, USA.
authors.forename: Danielle J
authors.initials: DJ
authors.lastname: Harvey
authors.affiliation: Division of Biostatistics, Department of Public Health Sciences, University of California, Davis, CA, USA.
authors.forename: Naomi
authors.initials: N
authors.lastname: Saito
mesh_terms: D000367:Age Factors; D000544:Alzheimer Disease / Q000150:complications / Q000175:diagnosis*; D000682:Amyloid / Q000378:metabolism; D001921:Brain / Q000473:pathology*; D060825:Cognitive Dysfunction / Q000209:etiology; D018450:Disease Progression; D006801:Humans; D008137:Longitudinal Studies; D008569:Memory Disorders / Q000209:etiology; D008609:Mental Status Schedule; D015337:Multicenter Studies as Topic; D059906:Neuroimaging / Q000379:methods*
chemical_list: D000682:Amyloid
keywords: Alzheimer's disease; Amyloid cascade hypothesis; Subjective memory complaints