title: Plasma amyloid beta-42 independently predicts both late-onset depression and Alzheimer disease.
abstract: OBJECTIVE
  Depression in the elderly might represent a prodromal phase of Alzheimer disease (AD). High levels of plasma amyloid beta-42 (Aβ42) were found in prestages of AD and also in depressed patients in cross-sectional studies. This study examined the association of emerging late-onset depression (LOD) and AD with plasma Aβ42 in a sample of never depressed and not demented persons at baseline.
  
  
  METHODS
  Prospective 5-year longitudinal study.
  
  
  METHODS
  A community dwelling of older adults (N = 331) from the Vienna Transdanube Aging study.
  
  
  METHODS
  Laboratory measurements, cognitive functioning, and depressive symptoms were assessed at baseline, 2.5, and 5 years follow-ups.
  
  
  RESULTS
  After exclusion of converters to AD, regression analysis revealed that higher plasma Aβ42 at baseline was a positive predictor for conversion to first episode of LOD. Independent of whether persons with mild cognitive impairment (MCI) at 2.5 years were included or excluded into regressions, higher plasma Aβ42 at baseline was a significant predictor for the development of probable or possible AD at 5 years. Higher conversion to AD was also associated with male gender but not with either higher scores on the Geriatric Depression Scale (GDS), with stroke or cerebral infarction nor apolipoprotein E ε4 allele. No association was found for an interaction between plasma Aβ42 levels and GDS.
  
  
  CONCLUSIONS
  Higher plasma Aβ42 at baseline predicted the development of first episode of LOD and conversion to probable or possible AD. Emerging depression as measured by scores on GDS at the 2.5-year follow-up, either alone or as an interaction factor with plasma Aβ42, failed to predict the conversion to AD at 5 years.
authors.affiliation: From the Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Austria. imrich.blasko@i-med.ac.at
authors.forename: Imrich
authors.initials: I
authors.lastname: Blasko
authors.forename: Georg
authors.initials: G
authors.lastname: Kemmler
authors.forename: Susanne
authors.initials: S
authors.lastname: Jungwirth
authors.forename: Ildiko
authors.initials: I
authors.lastname: Wichart
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Krampla
authors.forename: Silvia
authors.initials: S
authors.lastname: Weissgram
authors.forename: Kurt
authors.initials: K
authors.lastname: Jellinger
authors.forename: Karl Heinz
authors.initials: KH
authors.lastname: Tragl
authors.forename: Peter
authors.initials: P
authors.lastname: Fischer
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D016229:Amyloid beta-Peptides / Q000097:blood*; D053327:Apolipoprotein E4 / Q000235:genetics; D003072:Cognition Disorders / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D003866:Depressive Disorder / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D018450:Disease Progression; D005260:Female; D015577:Geriatric Assessment / Q000379:methods; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010446:Peptide Fragments / Q000097:blood*; D011237:Predictive Value of Tests; D012307:Risk Factors; D012727:Sex Characteristics
chemical_list: D016229:Amyloid beta-Peptides; D053327:Apolipoprotein E4; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42)