title: The relationship between plasma amyloid-β peptides and the medial temporal lobe in the homebound elderly.
abstract: BACKGROUND
  The ratio of high amyloid-β peptide40 (Aβ40) and low Aβ42 in plasma predicts the risk of Alzheimer's disease (AD) and is associated with episodic recall in depression. We thus examined the relationship between plasma Aβ levels and brain volumes.
  
  
  METHODS
  Homebound elders (N = 352) who had undergone brain MRI were used. Plasma Aβ1-40 and Aβ1-42 were measured by ELISA. Volumes of medial temporal regions, including the amygdala and hippocampus, were manually measured.
  
  
  RESULTS
  Amygdala volume was associated with log(10) of plasma Aβ1-42 (β = +0.19, SE = 0.07, p = 0.005) after adjusting for AD, infarcts, white matter hyperintensities and demographics. In the absence of dementia, decreasing quartiles of plasma Aβ1-42 (Mean + SD ml: Q4 = 4.1 ± 0.8; Q3 = 3.9 ± 0.7; Q2 = 3.6 ± 0.8 and Q1 = 3.7 ± 0.8, p = 0.01) and increasing quartiles of plasma Aβ1-40/1-42 ratio were associated with smaller amygdala volume. Those depressed subjects with a high plasma Aβ1-40/1-42 ratio had smaller amygdala (Mean + SD ml: 3.3 ± 0.8 vs. 3.6 ± 0.8, p = 0.04) and total brain volume (Mean + SD liter: 0.95 ± 0.07 vs. 1.04 ± 0.12, p = 0.005), and had a higher rate of MCI (67 vs. 36%, p = 0.02) than those with a low plasma Aβ1-40/1-42 ratio.
  
  
  CONCLUSIONS
  The combination of low plasma Aβ1-42 concentration and atrophy of the medial temporal lobe structures, which regulates mood and cognition, may represent a biomarker for a prodromal stage of AD.
authors.affiliation: Department of Psychiatry, Tufts Medical Center, Tufts University School of Medicine, MA, USA.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Sun
authors.forename: Rafeeque
authors.initials: R
authors.lastname: Bhadelia
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Liebson
authors.forename: Peter
authors.initials: P
authors.lastname: Bergethon
authors.forename: Marshal
authors.initials: M
authors.lastname: Folstein
authors.forename: Jay-Jiguang
authors.initials: JJ
authors.lastname: Zhu
authors.forename: D Mkaya
authors.initials: DM
authors.lastname: Mwamburi
authors.forename: Samuel
authors.initials: S
authors.lastname: Patz
authors.forename: Wei Qiao
authors.initials: WQ
authors.lastname: Qiu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000679:Amygdala / Q000473:pathology*; D016229:Amyloid beta-Peptides / Q000097:blood*; D000704:Analysis of Variance; D003072:Cognition Disorders / Q000097:blood / Q000473:pathology; D003704:Dementia / Q000097:blood / Q000175:diagnosis; D003863:Depression / Q000097:blood / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D018577:Homebound Persons / Q000523:psychology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D001523:Mental Disorders / Q000097:blood* / Q000473:pathology*; D011569:Psychiatric Status Rating Scales
chemical_list: D016229:Amyloid beta-Peptides