title: Alpha- and beta-secretase activity as a function of age and beta-amyloid in Down syndrome and normal brain.
abstract: Aged individuals with Down syndrome (DS) develop Alzheimer's disease (AD) neuropathology by the age of 40 years. The purpose of the current study was to measure age-associated changes in APP processing in 36 individuals with DS (5 months-69 years) and in 26 controls (5 months-100 years). Alpha-secretase significantly decreased with age in DS, particularly in cases over the age of 40 years and was stable in controls. The levels of C-terminal fragments of APP reflecting alpha-secretase processing (CTF-alpha) decreased with age in both groups. In both groups, there was significant increase in beta-secretase activity with age. CTF-beta remained constant with age in controls suggesting compensatory increases in turnover/clearance mechanisms. In DS, young individuals had the lowest CTF-beta levels that may reflect rapid conversion of beta-amyloid (Abeta) to soluble pools or efficient CTF-beta clearance mechanisms. Treatments to slow or prevent AD in the general population targeting secretase activity may be more efficacious in adults with DS if combined with approaches that enhance Abeta degradation and clearance.
authors.affiliation: Institute for Brain Aging & Dementia, CA, United States.
authors.forename: M
authors.initials: M
authors.lastname: Nistor
authors.forename: M
authors.initials: M
authors.lastname: Don
authors.forename: M
authors.initials: M
authors.lastname: Parekh
authors.forename: F
authors.initials: F
authors.lastname: Sarsoza
authors.forename: M
authors.initials: M
authors.lastname: Goodus
authors.forename: G E
authors.initials: GE
authors.lastname: Lopez
authors.forename: C
authors.initials: C
authors.lastname: Kawas
authors.forename: J
authors.initials: J
authors.lastname: Leverenz
authors.forename: E
authors.initials: E
authors.lastname: Doran
authors.forename: I T
authors.initials: IT
authors.lastname: Lott
authors.forename: M
authors.initials: M
authors.lastname: Hill
authors.forename: E
authors.initials: E
authors.lastname: Head
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism* / Q000473:pathology; D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000096:biosynthesis*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D004314:Down Syndrome / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D058225:Plaque, Amyloid / Q000201:enzymology / Q000473:pathology; D012016:Reference Values; D015854:Up-Regulation / Q000502:physiology
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D015415:Biomarkers; D053829:Amyloid Precursor Protein Secretases