title: Regional differences in white matter breakdown between frontotemporal dementia and early-onset Alzheimer's disease.
abstract: BACKGROUND
  White matter abnormalities have been associated with both behavioral variant frontotemporal dementia (bvFTD) and Alzheimer's disease (AD).
  
  
  OBJECTIVE
  Using MRI diffusion tensor imaging (DTI) measures, we compared white matter integrity between patients with bvFTD and those with early-onset AD and correlated these biomarkers with behavioral symptoms involving emotional blunting.
  
  
  METHODS
  We studied 8 bvFTD and 12 AD patients as well as 12 demographically-matched healthy controls (NCs). Using four DTI metrics (fractional anisotropy, axial diffusivity, radial diffusivity, and mean diffusivity), we assessed the frontal lobes (FWM) and genu of the corpus callosum (GWM), which are vulnerable late-myelinating regions, and a contrasting early-myelinating region (splenium of the corpus callosum). The Scale for Emotional Blunting Scale (SEB) was used to assess emotional functioning of the study participants.
  
  
  RESULTS
  Compared to AD patients and NCs, the bvFTD subjects exhibited significantly worse FWM and GWM integrity on all four DTI metrics sensitive to myelin and axonal integrity. In contrast, AD patients showed a numerical trend toward worse splenium of the corpus callosum integrity than bvFTD and NC groups. Significant associations between SEB ratings and GWM DTI measures were demonstrated in the combined bvFTD and AD sample. When examined separately, these relationships remained robust for the bvFTD group but not the AD group.
  
  
  CONCLUSIONS
  The regional DTI alterations suggest that FTD and AD are each associated with a characteristic distribution of white matter degradation. White matter breakdown in late-myelinating regions was associated with symptoms of emotional blunting, particularly within the bvFTD group.
authors.affiliation: Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
authors.forename: Po H
authors.initials: PH
authors.lastname: Lu
authors.affiliation: Department of Psychology, School of Behavioral Health, Loma Linda University, Loma Linda, CA, USA.
authors.forename: Grace J
authors.initials: GJ
authors.lastname: Lee
authors.affiliation: Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA Greater Los Angeles VA Healthcare System, West Los Angeles, CA, USA.
authors.forename: Jill
authors.initials: J
authors.lastname: Shapira
authors.affiliation: Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA Greater Los Angeles VA Healthcare System, West Los Angeles, CA, USA.
authors.forename: Elvira
authors.initials: E
authors.lastname: Jimenez
authors.affiliation: Greater Los Angeles VA Healthcare System, West Los Angeles, CA, USA.
authors.forename: Michelle J
authors.initials: MJ
authors.lastname: Mather
authors.affiliation: Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA Laboratory of Neuroimaging, Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Thompson
authors.affiliation: Laboratory of Neuroimaging, Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
authors.forename: George
authors.initials: G
authors.lastname: Bartzokis
authors.affiliation: Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA Greater Los Angeles VA Healthcare System, West Los Angeles, CA, USA.
authors.forename: Mario F
authors.initials: MF
authors.lastname: Mendez
mesh_terms: D000342:Affective Symptoms / Q000175:diagnosis / Q000473:pathology; D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis / Q000473:pathology*; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D003337:Corpus Callosum / Q000473:pathology; D056324:Diffusion Tensor Imaging; D005260:Female; D005625:Frontal Lobe / Q000473:pathology; D057180:Frontotemporal Dementia / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D011569:Psychiatric Status Rating Scales
keywords: Alzheimer's disease; behavioral variant; diffusion tensor imaging; early onset; frontotemporal dementia; magnetic resonance imaging; myelin; white matter