Recent studies suggest that longstanding findings of abnormal amygdala morphology in ASD may be related to symptoms of anxiety. To test this hypothesis, fifty-three children with ASD (mean age = 11.9) underwent structural MRI and were divided into subgroups to compare those with at least one anxiety disorder diagnosis (n = 29) to those without (n = 24) and to a typically developing control group (TDC; n = 37). Groups were matched on age and intellectual level. The ASD and anxiety group showed decreased right amygdala volume (controlled for total brain volume) relative to ASD without anxiety (p = .04) and TDCs (p = .068). Results suggest that youth with ASD and co-occurring anxiety have a distinct neurodevelopmental trajectory.
Keywords: Amygdala; Anxiety disorders; Brain morphometry; Comorbidity.