Widespread white matter degeneration preceding the onset of dementia

Alzheimers Dement. 2015 May;11(5):485-493.e2. doi: 10.1016/j.jalz.2014.04.518. Epub 2014 Jul 14.

Abstract

Background: Brain atrophy in subjects with mild cognitive impairment (MCI) introduces partial volume effects, limiting the sensitivity of diffusion tensor imaging to white matter microstructural degeneration. Appropriate correction isolates microstructural effects in MCI that might be precursors of Alzheimer's disease (AD).

Methods: Forty-eight participants (18 MCI, 15 AD, and 15 healthy controls) had magnetic resonance imaging scans and clinical evaluations at baseline and follow-up after 36 months. Ten MCI subjects were diagnosed with AD at follow-up and eight remained MCI. Free-water (FW) corrected measures on the white matter skeleton were compared between groups.

Results: FW corrected radial diffusivity, but not uncorrected radial diffusivity, was increased across the brain of the converted group compared with the nonconverted group (P < .05). The extent of increases was similar to that found comparing AD with controls.

Conclusion: Partial volume elimination reveals microstructural alterations preceding dementia. These alterations may prove to be an effective and feasible early biomarker of AD.

Keywords: Alzheimer's disease; Diffusion tensor imaging; Free-water imaging; Mild cognitive impairment; Partial volume elimination.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Anisotropy
  • Cognitive Dysfunction / complications
  • Dementia / etiology*
  • Diffusion Tensor Imaging
  • Disease Progression
  • Female
  • Humans
  • Image Processing, Computer-Assisted
  • Male
  • Mental Status Schedule
  • Middle Aged
  • Nerve Degeneration / complications*
  • Nerve Degeneration / pathology
  • Nerve Fibers, Myelinated / pathology*
  • Neuropsychological Tests
  • White Matter / pathology*