title: Anxiety is associated with increased risk of dementia in older Swedish twins.
abstract: BACKGROUND
  We asked whether anxiety is associated with prospective risk of dementia, and the extent to which genetic influences mediate this association.
  
  
  METHODS
  Nondemented twins (n = 1082) from the Swedish Adoption Twin Study of Aging completed an assessment of anxiety symptoms in 1984 and were followed for 28 years.
  
  
  RESULTS
  Baseline anxiety score, independent of depressive symptoms, was significantly associated with incident dementia over follow-up (hazard ratio [HR] = 1.04; 95% confidence interval [CI] = 1.01-1.06). There was 48% increased risk of becoming demented for those who had experienced high anxiety at any time compared with those who had not. In co-twin analyses, the association between anxiety symptoms and dementia was greater for dizygotic (HR = 1.11; 95% CI = 1.02-1.20) compared with monozygotic twins (HR = 1.06; 95% CI = 0.95-1.20), indicating genetic mediation.
  
  
  CONCLUSIONS
  Anxiety symptoms were associated with increased risk of dementia. Genetic factors common to dementia and anxiety partially mediated this association.
authors.affiliation: Department of Psychology, University of Southern California, Los Angeles, CA, USA. Electronic address: petkus@usc.edu.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Petkus
authors.affiliation: Department of Psychology, University of California, Riverside, CA, USA.
authors.forename: Chandra A
authors.initials: CA
authors.lastname: Reynolds
authors.affiliation: Psychology Service, VA San Diego Healthcare System; Department of Psychiatry, University of California, San Diego, CA, USA.
authors.forename: Julie Loebach
authors.initials: JL
authors.lastname: Wetherell
authors.affiliation: Department of Psychiatry, University of California, San Diego, CA, USA; VA Center of Excellence for Stress and Mental Health, San Diego, CA, USA.
authors.forename: William S
authors.initials: WS
authors.lastname: Kremen
authors.affiliation: Department of Psychology, University of Southern California, Los Angeles, CA, USA; Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Pedersen
authors.affiliation: Department of Psychology, University of Southern California, Los Angeles, CA, USA; Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Margaret
authors.initials: M
authors.lastname: Gatz
mesh_terms: D000368:Aged; D001007:Anxiety / Q000453:epidemiology* / Q000235:genetics; D003704:Dementia / Q000453:epidemiology* / Q000235:genetics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D012306:Risk; D013548:Sweden; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
keywords: Anxiety; Dementia; Depression; Genetics; Twins