AbstractBeyond core impairments in social interaction skills and restricted, repetitive behaviours, young people with autism spectrum disorder (ASD) often also suffer from debilitating mood and anxiety problems. The reasons for this overlap are poorly understood and often complicated by difficulties in symptom reporting in youth with ASD. This thesis used a multi-method approach to investigate two possible mechanisms underlying mood and anxiety problems in ASD youth, and examined the usefulness of neuroimaging methods (arterial spin labelling) to aid the detection of mood states without relying on clinical report.
We first investigated symptom reporting of irritability and physiological stress responses in boys with high-functioning ASD and typically-developing controls. Boys with ASD reported reliably on their irritability, and showed reduced cortisol and heart rate responsiveness to stress compared to controls. Cortisol hypo-responsiveness in boys with ASD was associated with irritability, while lower heart rate was associated predominantly with anxiety.
Second, we examined the interplay between ASD traits and anxiety during a neuroimaging reward paradigm in 1472 adolescents from the community. Shared and unique neural correlates of anxiety were found in those with high vs. low ASD traits; while specific brain activations during reward anticipation predicted future, new-onset anxiety in participants high on ASD traits. Symptoms of depression and irritability had minimal impact on the results.
Third, arterial spin labelling was sensitive to experimentally-induced mood states in healthy youth. It showed some usefulness for detecting specific mood states, whereby sad and happy moods were distinguished from neutral, but not from each other, based on brain activation patterns alone.
Our results suggest that some pathophysiological mechanisms of anxiety may be different in ASD youth compared to controls, bringing important clinical implications. The effects of anxiety on cortisol stress responsiveness, but not heart rate responsiveness or reward processing, may be better explained by co-occurring irritability.
|Date of Award
|Emily Simonoff (Supervisor) & Argyris Stringaris (Supervisor)