title: Whole brain N-acetylaspartate concentration is conserved throughout normal aging.
abstract: We hypothesize that normal aging implies neuronal durability, reflected by age-independent concentrations of their marker--the amino acid derivative N-acetylaspartate (NAA). To test this, we obtained the whole-brain and whole-head N-acetylaspartate concentrations (WBNAA and WHNAA) with proton magnetic resonance (MR) spectroscopy; and the fractional brain parenchyma volume (fBPV)--a metric of atrophy, by segmenting the magnetic resonance image (MRI) from 42 (18 male) healthy young (31.9 ± 5.8 years old) and 100 (64 male, 72.6 ± 7.3 years old) cognitively normal elderly. The 12.8 ± 1.9 mM WBNAA of the young was not significantly different from the 13.1 ± 3.1 mM in the elderly (p > 0.05). In contrast, both fBPV (87.3 ± 4.7% vs. 74.8 ± 4.8%) and WHNAA (11.1 ± 1.7 mM vs. 9.8 ± 2.4 mM) were significantly higher in the young (approximately 14%; p < 0.0001 for both). The similarity in mean WBNAA between 2 cohorts 4 decades of normal aging apart suggests that neuronal integrity is maintained across the lifespan. Clinically, WBNAA could be used as a marker for normal (hence, also abnormal) brain aging. In contrast, WHNAA and fBPV seem age-related suggesting that brain atrophy may occur without compromising the remaining tissue.
authors.affiliation: Department of Radiology, New York University School of Medicine, New York, NY, USA.
authors.forename: William E
authors.initials: WE
authors.lastname: Wu
authors.forename: Achim
authors.initials: A
authors.lastname: Gass
authors.forename: Lidia
authors.initials: L
authors.lastname: Glodzik
authors.forename: James S
authors.initials: JS
authors.lastname: Babb
authors.forename: Jochen
authors.initials: J
authors.lastname: Hirsch
authors.forename: Marc
authors.initials: M
authors.lastname: Sollberger
authors.forename: Lutz
authors.initials: L
authors.lastname: Achtnichts
authors.forename: Michael
authors.initials: M
authors.lastname: Amann
authors.forename: Andreas U
authors.initials: AU
authors.lastname: Monsch
authors.forename: Oded
authors.initials: O
authors.lastname: Gonen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism; D001284:Atrophy / Q000378:metabolism; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D001923:Brain Chemistry; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D009929:Organ Size
chemical_list: D015415:Biomarkers; D001224:Aspartic Acid; C000179:N-acetylaspartate