부산대학교 도서관

Attention-deficit/hyperactivity disorder (ADHD) and anxiety co-occur at above chance levels in both clinical and sub-clinical cases. However, little is known about the underlying neuropsychological basis of this overlap. In this thesis, we addressed this question by exploring a pattern of dysfunctional cognitive control linked to these conditions. Our hypothesis was that ADHD would be associated with core deficits in cognitive control in both non-emotional and emotional contexts. In addition, we anticipated cognitive control deficits in anxiety to manifest in situations involving processing of emotional stimuli and particularly in threat contexts. Furthermore, we predicted that the combination of these cognitive control challenges would be exacerbated in the case of co-occurring ADHD and anxiety. We investigated these hypotheses using eye-movement measurements in a Go/NoGo paradigm to examine inhibitory control (i.e., suppression of reflexive saccades) and sustained attention (i.e., saccadic execution) in emotional and non-emotional contexts. We also designed an eye-movement version of the Spatial Cueing paradigm to examine attentional orienting in the presence of emotional cue distractors using representations of another person's eye-gaze. The current thesis contains four empirical chapters discussing the relationship between ADHD and anxiety symptom dimensions (and their interaction) on task performance. We examined the Go/No-Go task using symptoms of ADHD and anxiety in typically developing (TD) children/adolescents (n= 27) and healthy adults (n=27) (Chapter 3), and symptoms of ADHD and Generalised Anxiety Disorder (GAD) in a larger sample of children and adolescents (n=68), that included both TD children/adolescents and clinical cases of ADHD and anxiety (Chapter 4). We then examined the Spatial Cueing task in the same samples across Chapters 5 and 6. High levels of ADHD were associated with impaired inhibitory control and disrupted processing, in the context of threat (such as angry faces) (Chapter 3) with reduced sustained attention regardless of the emotional valence of the stimuli used (Chapter 4). Individuals with ADHD did not effectively use social cues (i.e., poorer attentional orienting), especially in the presence of negative emotional expressions (such as angry and fearful faces) relative to other emotional expressions (Chapters 5 and 6). Anxiety symptoms were associated with faster processing of negative facial expressions (Chapter 3) and improved attentional orienting following social cues of negative emotional expressions, relative to other facial expressions (Chapter 5). Anxiety was also associated with better attentional orienting following social cues of angry faces relative to fearful faces (Chapter 6). In terms of the interactions between anxiety and ADHD, elevated anxiety symptoms were associated with attenuation of disrupted attentional processes found in ADHD including faster processing of negative emotional expressions relative to positive ones (Chapter 3 and 4), improved sustained attention (Chapter 4) and better attentional orienting processes (Chapters 5 and 6). Overall, our results showed that ADHD was associated with deficits in cognitive control, particularly in emotionally charged contexts. However, anxiety was associated with improved attentional processes in response to negative emotional stimuli. Contrary to our predictions, we found that co-occurring ADHD and anxiety were associated with improved attentional control and emotional processing. Overall, the synergistic effects between ADHD and anxiety provide evidence towards a potentially distinct cognitive phenotype.