title: Genetic and environmental contributions to separation anxiety: a meta-analytic approach to twin data.
abstract: BACKGROUND
  Separation anxiety disorder (SAD) and separation anxiety symptoms (SA) have been studied both epidemiologically and genetically; however, large between-studies discrepancies emerge relative to the role of genetic, shared-, and nonshared environmental influences on these conditions.
  
  
  METHODS
  Based upon available literature, 18 cohorts and 31,859 subjects belonging to twin samples in Europe, the United States, and Australia were included in three meta-analytic estimations of: the standardized variance components of etiological influences on SAD/SA, and on the effect of sex and rater.
  
  
  RESULTS
  Meta-analytic estimations carried out on all cohorts showed that within-family (genetic 43% and shared environmental 17%) factors explain most of individual differences for SAD/SA. Meta-heritability estimates were higher among females (.52) than males (.26), whereas nonshared environmental effects were stronger for the latter (.74) than for the former (.41). When SAD/SA was rated by parents, the shared environmental influences were higher than those obtained with self-assessment instruments (.23 versus .05), but this may reflect an age difference between subsamples.
  
  
  CONCLUSIONS
  A shared environmental effect is present and important in SAD/SA. Our results support at an etiological level the involvement of parents in treating SAD/SA in children, and the provision of specific strategies to parents to manage their own anxiety.
authors.affiliation: Academic Centre for the Study of Behavioural Plasticity, Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Scaini
authors.forename: Anna
authors.initials: A
authors.lastname: Ogliari
authors.forename: Thalia C
authors.initials: TC
authors.lastname: Eley
authors.forename: Helena M S
authors.initials: HM
authors.lastname: Zavos
authors.forename: Marco
authors.initials: M
authors.lastname: Battaglia
mesh_terms: D000293:Adolescent; D001010:Anxiety, Separation / Q000209:etiology*; D002648:Child; D002675:Child, Preschool; D004777:Environment; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D012737:Sex Factors; D018433:Twin Studies as Topic; D014427:Twins / Q000235:genetics / Q000523:psychology*