title: Genetic and environmental influences on separation anxiety disorder symptoms and their moderation by age and sex.
abstract: We estimated genetic and environmental influences on mother-rated DSM-III-R separation anxiety disorder (SAD) symptoms in 2043 3 to 18-year-old male and female twin pairs and their siblings (348 pairs) recruited from the Australian NH&MRC Twin Registry. Using DeFries and Fulker's (1985) multiple regression analysis, we found that genetic and shared environmental influences both contributed appreciably to variation in SAD symptoms (h2 = .47, SE = .07; c2 = .21, SE = .05) and were significantly moderated by both sex and age. Genetic influences were greater for girls than boys (h2 = .50 and .14, respectively), whereas shared environmental influences were greater for boys than girls (c2 = .51 and .21, respectively). Genetic influences increased with age. whereas shared environmental influences decreased with age. Shared environmental influences were greater in magnitude for twins than for nontwin siblings (c2 = .28 versus .13, respectively). Implications of these findings for theories of the cause of separation anxiety are discussed.
authors.affiliation: Emory University, Atlanta, Georgia, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Feigon
authors.forename: I D
authors.initials: ID
authors.lastname: Waldman
authors.forename: F
authors.initials: F
authors.lastname: Levy
authors.forename: D A
authors.initials: DA
authors.lastname: Hay
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001010:Anxiety, Separation / Q000235:genetics* / Q000523:psychology; D002648:Child; D002675:Child, Preschool; D004200:Diseases in Twins; D005260:Female; D006801:Humans; D008297:Male; D010552:Personality Assessment; D012737:Sex Factors; D012931:Social Environment