title: Conversion of mild cognitive impairment to Alzheimer disease predicted by hippocampal atrophy maps.
abstract: BACKGROUND
  While most patients with mild cognitive impairment (MCI) transition to Alzheimer disease (AD), others develop non-AD dementia, remain in the MCI state, or improve.
  
  
  OBJECTIVE
  To test the following hypotheses: smaller hippocampal volumes predict conversion of MCI to AD, whereas larger hippocampal volumes predict cognitive stability and/or improvement; and patients with MCI who convert to AD have greater atrophy in the CA1 hippocampal subfield and subiculum.
  
  
  METHODS
  Prospective longitudinal cohort study.
  
  
  METHODS
  University of California-Los Angeles Alzheimer's Disease Research Center.
  
  
  METHODS
  We followed up 20 MCI subjects clinically and neuropsychologically for 3 years.
  
  
  METHODS
  Baseline regional hippocampal atrophy was analyzed with region-of-interest and 3-dimensional hippocampal mapping techniques.
  
  
  RESULTS
  During the 3-year study, 6 patients developed AD (MCI-c), 7 remained stable (MCI-nc), and 7 improved (MCI-i). Patients with MCI-c had 9% smaller left and 13% smaller right mean hippocampal volumes compared with MCI-nc patients. Radial atrophy maps showed greater atrophy of the CA1 subregion in MCI-c. Patients with MCI-c had significantly smaller hippocampi than MCI-i patients (left, 24%; right, 27%). Volumetric analyses showed a trend for greater hippocampal atrophy in MCI-nc relative to MCI-i patients (eg, 16% volume loss). After permutation tests corrected for multiple comparison, the atrophy maps showed a significant difference on the right. Subicular differences were seen between MCI-c and MCI-i patients, and MCI-nc and MCI-i patients. Multiple linear regression analysis confirmed the group effect to be highly significant and independent of age, hemisphere, and Mini-Mental State Examination scores at baseline.
  
  
  CONCLUSIONS
  Smaller hippocampi and specifically CA1 and subicular involvement are associated with increased risk for conversion from MCI to AD. Patients with MCI-i tend to have larger hippocampal volumes and relative preservation of both the subiculum and CA1.
authors: Laboratory of Neuro Imaging, Department of Neurology, The David Geffen School of Medicine at UCLA, University of California-Los Angeles, Los Angeles, CA, USA. lapostolova@mednet.ucla.edu
authors: Liana G
authors: LG
authors: Apostolova
authors: Rebecca A
authors: RA
authors: Dutton
authors: Ivo D
authors: ID
authors: Dinov
authors: Kiralee M
authors: KM
authors: Hayashi
authors: Arthur W
authors: AW
authors: Toga
authors: Jeffrey L
authors: JL
authors: Cummings
authors: Paul M
authors: PM
authors: Thompson