title: A family study of Alzheimer disease and early- and late-onset depression in elderly patients.
abstract: BACKGROUND
  The substantial symptomatic overlap between depression and dementia in old age may be explained by common genetic vulnerability factors.
  
  
  METHODS
  We investigated this idea by comparing the occurrence of both disorders in first-degree relatives of 78 patients with Alzheimer disease (AD), of 74 with late-onset depression (onset age of > or = 60 years), of 78 with early-onset depression, of 53 with comorbid lifetime diagnoses of AD/depression, and of 162 population control subjects. Diagnostic information on their 3002 relatives was obtained from structured direct assessments and from family history interviews.
  
  
  RESULTS
  The 90-year lifetime incidence of primary progressive dementia was significantly higher in relatives of patients with AD (30%) and comorbid AD/depression (27%) than in relatives of patients with early-onset (21%) or late-onset (26%) depression, or of controls (22%) (P =.01). Lifetime incidence of depression was significantly higher in relatives of patients with early-onset depression (13%) than in relatives of patients with AD (10%) or controls (9.0%) (P =.006). Lifetime incidence of depression was similar in control relatives and in relatives of those patients with comorbid AD/depression (8.6%). Relatives of patients with late-onset depression also showed similar occurrence of depression until the age of 80 years, but the figure increased sharply thereafter to 19.1% by the age of 90 years.
  
  
  CONCLUSIONS
  Primary progressive dementia and early-onset depression represent clinical entities with distinct inheritance. Late-onset depression does not share substantial inheritance in common with dementia or with early-onset depression, but does show modest familial clustering.
authors.affiliation: Department of Psychiatry, University of Bonn, Venusberg, D-53105 Bonn, Germany. heun@uni-bonn.de
authors.forename: R
authors.initials: R
authors.lastname: Heun
authors.forename: A
authors.initials: A
authors.lastname: Papassotiropoulos
authors.forename: F
authors.initials: F
authors.lastname: Jessen
authors.forename: W
authors.initials: W
authors.lastname: Maier
authors.forename: J C
authors.initials: JC
authors.lastname: Breitner
mesh_terms: D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D015897:Comorbidity; D003866:Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D005190:Family; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data