title: Patients with vascular dementia due to microvascular pathology have significant hippocampal neuronal loss.
abstract: BACKGROUND
  Alzheimer's disease (AD) is characterised by functional impairment, cerebral atrophy, and degeneration of specific neuronal populations, especially pyramidal neurones of the cerebral cortex and hippocampal formation. Although patients with subcortical vascular dementia have been shown to have similar metabolic and volumetric deficits to those with AD, the underlying pathogenesis of these changes is poorly understood.
  
  
  OBJECTIVE
  To determine whether pyramidal cell loss occurs in small vessel disease (SVD) dementia by quantifying hippocampal volume and CA1 neurone number.
  
  
  METHODS
  Fifty four prospectively studied patients with dementia were screened, and four patients fulfilling criteria for SVD with no other significant neuropathological abnormality were identified. These were compared with five patients fulfilling criteria for AD and seven controls matched for age and sex. The hippocampal formation was serially sectioned, and the number of CA1 pyramidal neurones estimated using the optical dissector technique. Analysis of variance was used to evaluate group differences.
  
  
  RESULTS
  Patients in both the AD and SVD groups showed a substantial loss of pyramidal neurones from the CA1 region. The pattern of hippocampal atrophy and the degree of CA1 neuronal loss were similar in the two dementia groups.
  
  
  CONCLUSIONS
  These findings support recent in vivo studies showing similar metabolic deficits and atrophy in AD and subcortical vascular dementia. In addition, they provide evidence that the underlying cause of these abnormalities is a similar loss of neurones. Whereas the cause of the neuronal loss in AD is related to the deposition of abnormal proteins, the cause in SVD is unknown. In the absence of other pathologies, damage to cerebral microvasculature should be considered a likely candidate.
authors.affiliation: Centre for Education and Research on Ageing, Department of Medicine, University of Sydney, Sydney, NSW, Australia. jilliank@med.usyd.edu.au
authors.forename: J J
authors.initials: JJ
authors.lastname: Kril
authors.forename: S
authors.initials: S
authors.lastname: Patel
authors.forename: A J
authors.initials: AJ
authors.lastname: Harding
authors.forename: G M
authors.initials: GM
authors.lastname: Halliday
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001284:Atrophy; D016923:Cell Death; D015140:Dementia, Vascular / Q000503:physiopathology*; D005260:Female; D006624:Hippocampus / Q000166:cytology* / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017966:Pyramidal Cells / Q000473:pathology*