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The investigation of Chronic and Severe Irritability in a clinical sample of youths with Attention Deficit Hyperactivity Disorder

Colonna, Silvia 2020. The investigation of Chronic and Severe Irritability in a clinical sample of youths with Attention Deficit Hyperactivity Disorder. PhD Thesis, Cardiff University.
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Abstract

Chronic and severe irritability is an impairing condition associated with poor clinical and functional outcome. However, little is known about its nature, pathophysiological markers, and risk factors, which are essential to develop effective interventions. These knowledge gaps could be best addressed in youths with Attention Deficit Hyperactivity Disorder (ADHD). Chronic and severe irritability is highly prevalent in this population, leading to greater impairment than those with ADHD alone. Additionally, cognitive deficits seen in severely irritable youths greatly overlap with those observed in individuals with ADHD. Thus, investigating chronic and severe irritability in this population might also help understand the problematic heterogeneity of ADHD, which is observed at clinical, cognitive, and aetiological levels, that impact upon both clinical and research practice. This thesis had three main aims. The first aim was to explore the possible bi- dimensional nature of chronic and severe irritability, composed of phasic and tonic dimensions, in a clinical sample of children with ADHD. This was achieved by comparing the extent to which phasic and tonic irritability were associated with cross- sectional and longitudinal correlates of ADHD. Findings failed to support a clear distinction between these two dimensions, due to their similar pattern of associations, the strength of which did not differ between irritability dimensions. Chronic and severe irritability was thus considered unidimensional in the following studies of this PhD project. Nonetheless, both phasic and tonic irritability were associated with a poor clinical functioning, supporting the clinical relevance of this phenotype in those with ADHD. The second aim of this thesis was then to explore pathophysiological markers of chronic and severe irritability, possibly leading to impairments in this population. The hypothesis was that chronic and severe irritability measured at baseline predicted poor Hot (as opposed to Cool) cognitive functioning at follow-up; however, this was not supported by the results obtained. The third and final aim of this thesis was to look at common genetic risk associated with irritability in relation to chronic and severe irritability symptom severity (measured at baseline) and Hot cognitive functioning (measured at follow-up). Investigating pathophysiological markers of chronic and severe irritability at a different level of analysis (i.e., biological underpinnings) led however to similar conclusions. Although common genetic risk for irritability seemed to influence the symptom presentation of this phenotype, it was not associated with Hot cognitive functioning. Taken together these results seem to suggest that chronic and severe irritability is a marker of severity in those with ADHD, and that future interventions should not target Cool or Hot cognitive functioning. However, considering the pioneering nature of these studies, more research is needed to draw stronger conclusions, possibly using a comprehensive measure of irritability, and addressing other cognitive markers; this might yield different results.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Psychology
Subjects: B Philosophy. Psychology. Religion > BF Psychology
Date of First Compliant Deposit: 10 September 2020
Date of Acceptance: 9 September 2020
Last Modified: 25 May 2021 01:28
URI: https://orca.cardiff.ac.uk/id/eprint/134765

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