Exploring anxiety symptoms in a large-scale twin study of children with autism spectrum disorders, their co-twins and controls

Abstract

Background Although many children with autism spectrum disorders (ASDs) experience difficulties with anxiety, the manifestation of these difficulties remains unresolved. The current study assessed anxiety in a large population-based twin sample, aged 10-15 years. Phenotypic analyses were used to explore anxiety symptoms in children with ASDs, their unaffected co-twins and a control sample. Methods Participants included 146 families from the Twins Early Development Study (TEDS) where one or both children had a suspected ASD. Eighty control families were also included. The Revised Child Anxiety and Depression scale (Chorpita, Yim, Moffitt, Umemoto & Francis, 2000) was completed (self- and parent-report), along with diagnostic and cognitive tests. Children were categorized into four groups (a) ASD (b) Broader Autism Phenotype (BAP: mainly co-twins of children with ASDs, with high subclinical autistic traits) (c) unaffected co-twins (with neither ASDs nor BAP) (d) controls. Results Children in the ASD and BAP groups scored significantly higher than controls for all parent-rated (although not child-rated) anxiety subscales. There were no significant differences between the ASD and BAP groups for any of the parent-rated anxiety subscales. Compared with controls, unaffected co-twins showed significantly heightened Social Anxiety, Generalized Anxiety, and Panic symptoms. Significant associations were observed between certain anxiety subscales and both IQ and ASD symptoms. For example, greater parent-rated Social Anxiety was associated with higher IQ and increased social and communicative impairments. Significant interrater correlations were observed for anxiety reports in children with ASDs (r =.27-.54; p