title: Infrared spectroscopy: a reagent-free method to distinguish Alzheimer's disease patients from normal-aging subjects.
abstract: The physiopathogenesis of Alzheimer's disease (AD) is related to various biochemical mechanisms that may be reflected by changes in plasma components. In the current study, Fourier transform-infrared (FT-IR) spectroscopy was used to identify these biochemical variations by monitoring spectral differences in the plasma of 40 AD patients compared with those of 112 control subjects. A hierarchical classification in the whole mid-infrared region allowed a clear separation between AD and controls (C) that was optimized by using a restricted spectral range (1480-1428 cm(-1)). Spectral changes confirmed vibration differences between AD and C mostly related to modified lipid and nucleic acid structures involved in oxidative stress-dependent processes of AD. Moreover, the analysis of samples in the 1480-910-cm(-1) region allowed the distinction between C and AD with an accuracy of 98.4% and showed 2 subgroups C(1) and C(2) within the C group. Interestingly, the C(1) subgroup was located closer to the AD group than the C(2) subgroup, which suggests biochemical differences within the nondemented subjects. Biochemical studies revealed a significant increase in a specific marker of oxidative stress, F8-isoprostanes (8-epi-PGF2alpha) levels, in the plasma of AD patients as compared with total controls and subgroup C(2) but not subgroup C(1). Thus, these results suggest that use of FT-IR spectroscopy could be valuable to distinguish AD patients from normal-aging subjects.
authors.affiliation: INSERM U876, Université Bordeaux, France. evelyne.peuchant@biomemohv.u-bordeaux2.fr
authors.forename: Evelyne
authors.initials: E
authors.lastname: Peuchant
authors.forename: Sandrine
authors.initials: S
authors.lastname: Richard-Harston
authors.forename: Isabelle
authors.initials: I
authors.lastname: Bourdel-Marchasson
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Dartigues
authors.forename: Luc
authors.initials: L
authors.lastname: Letenneur
authors.forename: Pascale
authors.initials: P
authors.lastname: Barberger-Gateau
authors.forename: Sandrine
authors.initials: S
authors.lastname: Arnaud-Dabernat
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Daniel
mesh_terms: D000368:Aged; D000375:Aging; D000544:Alzheimer Disease / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D010054:Brief Psychiatric Rating Scale; D003072:Cognition Disorders / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D003937:Diagnosis, Differential; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D018384:Oxidative Stress / Q000502:physiology; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D013055:Spectrophotometry, Infrared
chemical_list: D015415:Biomarkers