Critical Problem Anxiety disorders are extremely common among individuals with autism spectrum disorder (ASD), occurring at four times the rate of the general population. The presence of an anxiety disorder negatively affects family functioning, friendship development, and school functioning. Later in life, anxiety places adolescents with ASD at risk for social isolation and employment difficulties. Despite the fact that anxiety disorders are common and impairing in individuals with ASD, we still know little about the early risk factors for anxiety in ASD, especially in preschool age children when anxiety disorders first manifest. Thus, treatment has focused on helping older children and adults with ASD with an anxiety disorder, rather than addressing symptoms when they first begin or even preventing the onset of an anxiety disorder. Our long-term goal is to be able to identify children with ASD who are at risk for developing an anxiety disorder as early as possible so that early intervention can target specific symptoms that put a child with ASD at risk for developing an anxiety disorder. If this were possible, it might be possible to prevent full-fledged anxiety disorders from developing, offering a more positive outcome for many people with ASD. Recent research is beginning to provide some clues regarding early risk factors for anxiety in individuals with ASD. Specifically, studies suggest that sensory over-responsivity -- a set of symptoms characterized by heightened and unusual reactivity to sensory stimuli that occurs more frequently among children with ASD than typically developing children -- is associated with anxiety in individuals with ASD. Sensory over-responsivity emerges early in life and is often a disabling condition, as it can be associated with avoidance, aggression, lower levels of social and adaptive behavior and food selectivity. Higher rates of both sensory over-responsivity and anxiety are also associated with chronic gastrointestinal (GI) and sleep problems. We hypothesize that many of the negative outcomes associated with sensory over-responsivity, such as avoidance, aggression, and GI problems, primarily occur when sensory over-responsivity leads to the development of an anxiety disorder. The goal of the present research is to conduct an in-depth study of the relationship between sensory over-responsivity and anxiety symptoms in preschool age children with ASD, using parent report, observation, and brain-based measures (brain waves or EEG). In addition, we will explore whether impairments in the ability to disengage attention from a stimulus further contributes to the development of anxiety. Attention-shifting can help reduce a child's level of anxiety by allowing the child to direct his or her attention away from threatening stimuli and instead focus his or her attention on adaptive stimuli. Innovation and Impact Very few studies on the development of anxiety in young children with ASD have been conducted. We know very little about the early risk factors for anxiety in ASD, and no specific interventions exist that focus on prevention of anxiety disorders in ASD. Similarly, very little is understood about the brain-basis of sensory over-responsivity even though it causes distress and impairment for individuals with ASD and is now included as a symptom in the new DSM (Diagnostic and Statistical Manual of Mental Disorders) diagnostic criteria for ASD. Thus, this study represents a new direction in autism research, and if successful, will set the stage for a program of research by our group focused on early detection, treatment, and prevention of anxiety disorders in individuals with ASD. Although this project is focused on younger children, the risk factors for anxiety identified in the present study also will help expand our understanding of sensory over-responsivity and treatments for anxiety in older individuals with ASD. We are exploring several innovative measures that, if validated, could advance the field of autism research. Specifically, we are exploring novel neurophysiological measures of sensory over-responsivity and attentional control that could serve as sensitive biomarkers of risk for anxiety in ASD and be used as outcome measures in treatment studies. Furthermore, we are exploring automated methods for measuring attention that are nonintrusive, more feasible, and less expensive than current methods based on eye-tracking and coding. These low-cost, automated methods will accelerate the translation of our findings into real-world clinical settings.