Comorbidity of autism spectrum disorders and anxiety disorders: Insights from neuronal circuitry studies

Autism spectrum disorders are highly comorbid with anxiety disorders, with comorbid anxiety increasingly being recognised as a major cause of quality-of-life reduction for many individuals with an autism spectrum disorder. This comorbidity is underpinned by dysfunction in a group of core neural circuits which promotes the core symptomatology associated with these conditions. These circuits have been studied extensively in both humans and preclinical models, and in this review we provide an up-to-date summary of the primary circuits which control the behaviours associated with both autism spectrum disorders and anxiety disorders. These include the prefrontal cortical-amygdala circuit, the hippocampal formation, basal ganglia and the hypothalamus. We will also detail how dysfunction within these circuits converge to promote the phenotypes observed in these conditions. Finally, we propose a series of suggestions to resolve current controversies and advance knowledge towards establishing a circuit-level understanding of the relationship between these two disorders.