title: Amyloid-associated depression: a prodromal depression of Alzheimer disease?
abstract: BACKGROUND
  A high ratio of plasma amyloid-beta peptide 40 (Abeta(40)) to Abeta(42), determined by both high Abeta(40) and low Abeta(42) levels, increases the risk of Alzheimer disease. In a previous study, we reported that depression is also associated with low plasma Abeta(42) levels in the elderly population.
  
  
  OBJECTIVE
  To characterize plasma Abeta(40):Abeta(42) ratio and cognitive function in elderly individuals with and without depression.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Homecare agencies.
  
  
  METHODS
  A total of 995 homebound elderly individuals of whom 348 were defined as depressed by a Center for Epidemiological Studies Depression score of 16 or greater.
  
  
  METHODS
  Cognitive domains of memory, language, executive, and visuospatial functions according to levels of plasma Abeta(40) and Abeta(42) peptides.
  
  
  RESULTS
  Subjects with depression had lower plasma Abeta(42) levels (median, 14.1 vs 19.2 pg/mL; P = .006) and a higher plasma Abeta(40):Abeta(42) ratio (median, 8.9 vs 6.4; P < .001) than did those without depression in the absence of cardiovascular disease and antidepressant use. The interaction between depression and plasma Abeta(40):Abeta(42) ratio was associated with lower memory score (beta = -1.9, SE = 0.7, P = .006) after adjusting for potentially confounders. Relative to those without depression, "amyloid-associated depression," defined by presence of depression and a high plasma Abeta(40):Abeta(42) ratio, was associated with greater impairment in memory, visuospatial ability, and executive function; in contrast, nonamyloid depression was not associated with memory impairment but with other cognitive disabilities.
  
  
  CONCLUSIONS
  Amyloid-associated depression may define a subtype of depression representing a prodromal manifestation of Alzheimer disease.
authors.affiliation: Department of Psychiatry, Tufts-New England Medical Center, Campus Box 1007, 750 Washington St, Boston, MA 02111, USA.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Sun
authors.forename: David C
authors.initials: DC
authors.lastname: Steffens
authors.forename: Rhoda
authors.initials: R
authors.lastname: Au
authors.forename: Marshal
authors.initials: M
authors.lastname: Folstein
authors.forename: Paul
authors.initials: P
authors.lastname: Summergrad
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Yee
authors.forename: Irwin
authors.initials: I
authors.lastname: Rosenberg
authors.forename: D Mkaya
authors.initials: DM
authors.lastname: Mwamburi
authors.forename: Wei Qiao
authors.initials: WQ
authors.lastname: Qiu
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000097:blood* / Q000150:complications*; D016229:Amyloid beta-Peptides / Q000097:blood* / Q000276:immunology; D003072:Cognition Disorders / Q000097:blood / Q000175:diagnosis / Q000209:etiology; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000209:etiology* / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000209:etiology; D009483:Neuropsychological Tests; D010446:Peptide Fragments / Q000097:blood* / Q000276:immunology; D015995:Prevalence; D012720:Severity of Illness Index
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); C512364:beta-amyloid peptide (29-42)