GENETIC AND ENVIRONMENTAL-INFLUENCES ON CHILD REPORTS OF MANIFEST ANXIETY AND SYMPTOMS OF SEPARATION ANXIETY AND OVERANXIOUS DISORDERS - A COMMUNITY-BASED TWIN STUDY

Genetic and environmental influences in the determination of individua l differences in self-reported symptoms of separation anxiety (SAD), o veranxious disorder (OAD), and manifest anxiety (MANX) were evaluated in children and adolescents for three age groups (8-10, 11-13, and 14- 16). Symptom counts for SAD and OAD were assessed for 1412 twin pairs using the children's version of the Child and Adolescent Psychiatric A ssessment, and MANX scores were based on child report from die Revised Children's Manifest Anxiety Scales. Despite significant age and gende r differences in thresholds of liability for child reports of symptoms of SAD and OAD, additive genetic and environmental effects could be s et equal across age and gender for these variables. For MANX, however, the best-fitting model was a common effects sex-limitation model with estimates of heritability varying dependent upon age and gender. Para meter estimates from the ACE models of OAD and SAD showed that additiv e genetic variation was a necessary component in the explanation of in dividual differences in child-reported symptoms of OAD (h(2) = .37) ac ross gender, but does not appear to be a major contributor to the expl anation of individual differences in symptoms of SAD reported by child ren. Shared environmental effects (c(2) = .40) were found to play a mo derate role for SAD but could be dropped from the model for OAD and fr om all of the age groups for MANX, although the parameter approached s ignificance among 11 yr to 13-year-old males.