title: The development of fears from early adolesence to young adulthood: a multivariate study.
abstract: BACKGROUND
  Common fears change over development. Genetic and environmental risk factors for fears are partly shared across fears and partly fear-specific. The nature of the changes in common and fear-specific genetic and environmental risk factors over time is unknown.
  
  
  METHODS
  Self-reported fears were obtained at ages 13-14, 16-17 and 19-20 from 2404 twins in the Swedish Twin Study of Child and Adolescent Development. A multivariate longitudinal twin analysis was conducted with Mx.
  
  
  RESULTS
  Eighteen individual items formed four fear factors: animal, blood-injury, situational, and social. The best-fit model had no quantitative or qualitative sex effects or shared environmental effects, but included a strong common factor with a stable cross-time structure with highest loadings on situational and lowest loadings on social fears. New common and fear-specific genetic risk factors emerged over development. With increasing age, genetic effects declined in overall importance and became more fear-specific. Cross-time continuity in specific genetic effects was highest for animal and lowest for social fears. Social fears had a 'burst' of specific genetic effects in late adolescence. Individual-specific environmental factors impacted both on the general fear factor and on specific fears. Compared to genetic effects, the impact of the unique environment was more time-specific.
  
  
  CONCLUSIONS
  Genetic and environmental risk factors for individual fears are partly mediated through a common fear factor and are partly fear-specific in their effect. The developmental pattern of these risk factors is complex and dynamic with new common and specific genetic effects arising in late adolescence and early adulthood.
authors.affiliation: Virginia Institute of Psychiatric and Behavioral Genetics, Medical College of Virginia/Virginia Commonwealth University, Richmond, VA 23298-0126, USA. kendler@vcu.edu
authors.forename: K S
authors.initials: KS
authors.lastname: Kendler
authors.forename: C O
authors.initials: CO
authors.lastname: Gardner
authors.forename: P
authors.initials: P
authors.lastname: Annas
authors.forename: P
authors.initials: P
authors.lastname: Lichtenstein
mesh_terms: D000293:Adolescent; D002648:Child; D005239:Fear; D005260:Female; D006801:Humans; D008297:Male; D010698:Phobic Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology*; D011795:Surveys and Questionnaires; D014427:Twins; D055815:Young Adult