title: Differential synaptic loss in the cortex in Alzheimer's disease: a study using archival material.
abstract: We have developed techniques to utilize immunocytochemical localization of synaptic protein (SNAP-25) in conjunction with image analysis to investigate synaptic loss in readily available archival material. Sections from 5 cortical regions were examined in cases of Alzheimer's disease (n = 7) and controls (n = 5). Image analysis was used to determine a relative synaptic index (RSI) and probe for changes in synaptic integrity. RSI value for cortical regions did not differ in controls. RSIs from sulci and gyri were significantly correlated in Brodmann areas 6, 9 and 18 (40 and 52 approached significance). Cases with Alzheimer's disease showed decreases in sulcal and gyral RSI values of between 60% (Brodmann area 6 < 0.01) and 10% (Brodmann area 18 > 0.4) and a lack of correlation in sulco-gyral values except in Brodmann area 18. We have demonstrated that synaptic pathology is heterogeneous with frontal cortex most and occipital cortex least affected. Sulci and gyri are affected to different degrees. The underlying cytoarchitecture of the cortex and its pattern of connectivity appears to have a considerable influence on the degree and extent of synaptic pathology.
authors.affiliation: Department of Anatomy, St Mary's Hospital Medical School, Imperial College, London.
authors.forename: J
authors.initials: J
authors.lastname: Clinton
authors.forename: S E
authors.initials: SE
authors.lastname: Blackman
authors.forename: M C
authors.initials: MC
authors.lastname: Royston
authors.forename: G W
authors.initials: GW
authors.lastname: Roberts
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000378:metabolism / Q000473:pathology*; D002540:Cerebral Cortex / Q000737:chemistry / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008297:Male; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins / Q000032:analysis*; D013569:Synapses / Q000737:chemistry*; D050825:Synaptosomal-Associated Protein 25
chemical_list: D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C494208:SNAP25 protein, human; D050825:Synaptosomal-Associated Protein 25