title: beta-Amyloid protein immunoreactivity in skin is not a reliable marker of Alzheimer's disease. An autopsy-controlled study.
abstract: OBJECTIVE
  As a possible diagnostic marker for Alzheimer's disease (AD), we investigated beta-amyloid protein (beta/A4) immunoreactivity in skin. Furthermore, we studied the presence of beta-amyloid precursor protein 695 immunoreactivity in skin.
  
  
  METHODS
  Lifetime skin biopsy specimens were stained for beta/A4 and beta-amyloid precursor protein 695. The follow-up period was 12 months. We determined the correlation between beta/A4 immunoreactivity in skin and brain in patients with a neuropathologic diagnosis.
  
  
  METHODS
  All patients with dementia were hospitalized; most of them had moderate to severe dementia. Aged nondemented controls were residents of a nursing home. The Down's syndrome (DS) group included both hospitalized and ambulatory patients. Young nondemented controls were medical students or staff members who volunteered for the study.
  
  
  METHODS
  The study included a total of 111 subjects. Thirty-five patients had probable AD, nine had possible AD, 15 had multi-infarct dementia, one had idiopathic Parkinson's disease, and one had Parkinson's disease and possible AD. There were also 19 elderly nondemented controls, 23 patients with DS, and eight young nondemented controls.
  
  
  METHODS
  Immunohistochemical detection of beta/A4 in skin and correlation to the diagnosis of AD.
  
  
  RESULTS
  Immunopositivity for beta/A4 antibody was present in and around the endothelium of dermal blood vessels in a proportion of patients with AD and multi-infarct dementia as well as elderly controls. The patients with sporadic AD displayed beta/A4 immunoreactivity significantly more frequently than did patients with familial AD, patients with multi-infarct dementia, and controls. The beta/A4 immunopositivity in skin was rare in the patients with DS and not present in young controls. Instead, 48% of patients with DS but none of other groups had beta-amyloid precursor protein 695 immunoreactivity in skin. Only four (31%) of 13 patients with neuropathologically confirmed AD had shown endothelial beta/A4 immunopositivity in skin biopsy specimens while alive.
  
  
  CONCLUSIONS
  Our results do not support beta/A4 as a diagnostic marker for AD.
authors.affiliation: Department of Neurology, University of Kuopio, Findland.
authors.forename: O
authors.initials: O
authors.lastname: Heinonen
authors.forename: H
authors.initials: H
authors.lastname: Soininen
authors.forename: S
authors.initials: S
authors.lastname: Syrjänen
authors.forename: H
authors.initials: H
authors.lastname: Neittaanmäki
authors.forename: L
authors.initials: L
authors.lastname: Paljärvi
authors.forename: O
authors.initials: O
authors.lastname: Kosunen
authors.forename: K
authors.initials: K
authors.lastname: Syrjänen
authors.forename: P
authors.initials: P
authors.lastname: Riekkinen
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000032:analysis*; D015415:Biomarkers / Q000032:analysis; D001923:Brain Chemistry; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D012867:Skin / Q000737:chemistry* / Q000473:pathology
chemical_list: D016229:Amyloid beta-Peptides; D015415:Biomarkers