title: Neuroimaging of individuals with Down's syndrome at-risk for dementia: evidence for possible compensatory events.
abstract: BACKGROUND
  We report functional and structural brain indicators that may precede the onset of dementia in individuals with Down's syndrome (DS).
  
  
  METHODS
  Middle-aged adults with DS (n=19), a group known to be at high risk for dementia, were studied with (1) positron emission tomography (PET) to determine cerebral glucose metabolic rate (GMR), (2) structural magnetic resonance imaging (MRI) to determine gray matter volume (GM), and (3) ratings of potential dementia indicators based on a structured interview of caregiver observations designed to evaluate individuals with low intelligence.
  
  
  RESULTS
  Although none of the participants showed clinical signs of dementia, ratings of dementia indicators were correlated to both functional and structural imaging. The strongest correlations (p<.05, corrected for multiple comparisons) included the combination of higher GMR and decreased GM volume in parts of the temporal cortex, including the parahippocampus/hippocampus, in the thalamus, caudate, and frontal lobe (BA 47).
  
  
  CONCLUSIONS
  The combination of increased GMR overlapping with less gray matter in these areas may be consistent with a compensatory brain response to an early stage of the disease process.
authors.affiliation: Department of Pediatrics, University of California, Irvine 92697-4475, USA. rjhaier@uci.edu
authors.forename: R J
authors.initials: RJ
authors.lastname: Haier
authors.forename: K
authors.initials: K
authors.lastname: Head
authors.forename: E
authors.initials: E
authors.lastname: Head
authors.forename: I T
authors.initials: IT
authors.lastname: Lott
mesh_terms: D000328:Adult; D001923:Brain Chemistry / Q000502:physiology; D003071:Cognition / Q000502:physiology; D003627:Data Interpretation, Statistical; D003704:Dementia / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D004314:Down Syndrome / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D004644:Emotions / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007206:Individuality; D007700:Kinetics; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011569:Psychiatric Status Rating Scales; D012306:Risk
chemical_list: D005947:Glucose