title: Microbleeds in atypical presentations of Alzheimer's disease: a comparison to dementia of the Alzheimer's type.
abstract: BACKGROUND
  Microbleeds in the brain have been shown to occur in Alzheimer's disease (AD), affecting approximately a third of subjects that present with typical dementia of the Alzheimer's type (DAT). However, little is known about the frequency or distribution of microbleeds in subjects with AD that present with atypical clinical presentations.
  
  
  OBJECTIVE
  To determine whether the frequency and regional distribution of microbleeds in atypical AD differs from that observed in subjects with DAT, and to determine whether microbleeds in atypical AD are associated with age, demographics, or cognitive impairment.
  
  
  METHODS
  Fifty-five subjects with amyloid-β deposition on Pittsburgh compound B (PiB) PET who presented with predominant language (n = 37) or visuospatial/perceptual (n = 18) deficits underwent T2*weighted MRI. These subjects were compared to 41 PiB-positive subjects with DAT. Microbleeds were identified and assigned a lobar location.
  
  
  RESULTS
  The proportion of subjects with microbleeds did not differ between atypical AD (42%) and DAT (32%). However, atypical AD had larger numbers of microbleeds than DAT. In addition, the topographic distribution of microbleeds differed between atypical AD and DAT, with atypical AD showing the highest density of microbleeds in the frontal lobes. Among atypical AD, number of microbleeds was associated with age, but not gender or cognition. Microbleeds were more common in subjects with language (51%) versus visuospatial/perceptual deficits (22%).
  
  
  CONCLUSIONS
  Microbleeds are relatively common in both DAT and atypical AD, although atypical AD subjects appear to be at particular risk for developing large numbers of microbleeds and for developing microbleeds in the frontal lobe.
authors: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors: Jennifer L
authors: JL
authors: Whitwell
authors: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors: Kejal
authors: K
authors: Kantarci
authors: Department of Health Sciences Research (Biostatistics), Mayo Clinic, Rochester, MN, USA.
authors: Stephen D
authors: SD
authors: Weigand
authors: Department of Health Sciences Research (Biostatistics), Mayo Clinic, Rochester, MN, USA.
authors: Emily S
authors: ES
authors: Lundt
authors: Department of Radiology, Mayo Clinic, Rochester, MN, USA Department of Information Technology, Mayo Clinic, Rochester, MN, USA.
authors: Jeffrey L
authors: JL
authors: Gunter
authors: Department of Neurology, Mayo Clinic, Rochester, MN, USA.
authors: Joseph R
authors: JR
authors: Duffy
authors: Department of Neurology, Mayo Clinic, Rochester, MN, USA.
authors: Edythe A
authors: EA
authors: Strand
authors: Department of Psychiatry and Psychology (Division of Neuropsychology), Mayo Clinic, Rochester, MN, USA.
authors: Mary M
authors: MM
authors: Machulda
authors: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors: Anthony J
authors: AJ
authors: Spychalla
authors: Department of Neurology, Mayo Clinic, Rochester, MN, USA.
authors: Daniel A
authors: DA
authors: Drubach
authors: Department of Neurology, Mayo Clinic, Rochester, MN, USA.
authors: Ronald C
authors: RC
authors: Petersen
authors: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors: Val J
authors: VJ
authors: Lowe
authors: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors: Clifford R
authors: CR
authors: Jack
authors: Department of Neurology, Mayo Clinic, Rochester, MN, USA.
authors: Keith A
authors: KA
authors: Josephs
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D016229:Amyloid beta-Peptides / Q000378:metabolism; D000814:Aniline Compounds; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D002543:Cerebral Hemorrhage / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D013844:Thiazoles
chemical_list: C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; D016229:Amyloid beta-Peptides; D000814:Aniline Compounds; D019275:Radiopharmaceuticals; D013844:Thiazoles
keywords: Alzheimer's disease; amyloid-β; dementia of the Alzheimer's type; early-onset Alzheimer's disease; logopenic; magnetic resonance imaging; microbleeds; positron emission tomography; posterior cortical atrophy
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