title: Age transformation of combined hippocampus and amygdala volume improves diagnostic accuracy in Alzheimer's disease.
abstract: OBJECTIVE
  The specificity of magnetic resonance imaging (MRI)-based hippocampal measurements in detecting Alzheimer's disease (AD) pathology is reduced by an age-related reduction of the hippocampus volume. We propose an adjustment for this age effect to increase the diagnostic accuracy of hippocampal volumes in AD.
  
  
  METHODS
  Using an orthogonal rotational transformation of the coordinate system, values of MRI-determined volumes of hippocampus-amygdala formation (HAF) were transformed according to the age effect in 27 AD patients and 28 age- and sex-matched healthy control subjects.
  
  
  RESULTS
  The age transformation increased the diagnostic accuracy of HAF volumes in the study sample and in an independent sample from the literature. The age-transformed HAF volume predicted AD in a subject with mild cognitive impairment (MCI) with later biopsy-confirmed AD.
  
  
  CONCLUSIONS
  Age transformation may provide an easily applicable method to increase the clinical diagnostic accuracy of hippocampal measurements by considering the effect of aging on hippocampus volume.
authors.affiliation: Dementia Research and Neuroimaging Section, Memory Clinic, Department of Psychiatry, Ludwig-Maximilian University, Nussbaumstr.7, 80336, Munich, Germany. hampel@psy.med.uni-muenchen.de
authors.forename: Harald
authors.initials: H
authors.lastname: Hampel
authors.forename: Stefan J
authors.initials: SJ
authors.lastname: Teipel
authors.forename: Wolfram
authors.initials: W
authors.lastname: Bayer
authors.forename: Gene E
authors.initials: GE
authors.lastname: Alexander
authors.forename: Robert
authors.initials: R
authors.lastname: Schwarz
authors.forename: Mark B
authors.initials: MB
authors.lastname: Schapiro
authors.forename: Stanley I
authors.initials: SI
authors.lastname: Rapoport
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Möller
mesh_terms: D000367:Age Factors; D000368:Aged; D000375:Aging; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000473:pathology; D000679:Amygdala / Q000473:pathology*; D001706:Biopsy; D016002:Discriminant Analysis; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D011237:Predictive Value of Tests; D012372:ROC Curve; D012680:Sensitivity and Specificity