The relationship between emotion dysregulation and the classical symptoms of Attention Deficit Hyperactivity Disorder

Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder classically defined by either attentional dysfunction, hyperactive/impulsive behaviour, or both. More recently, emotion dysregulation has been proposed as an additional pervasive symptom that should be considered, however its relationship to the classical symptoms is unknown. This thesis aimed to investigate the relationship between emotion dysregulation and ADHD-like traits in non-clinical groups of adults. The first chapter reviewed the background of ADHD and emotion dysregulation as a new core symptom of ADHD, leading to the first study which examined the core ADHD-like traits and emotion dysregulation using self-report measures - the Adult ADHD Self-Report Scale (ASRS) and the Difficulties in Emotion Regulation Scale (DERS). The total ASRS scale scores (as well as with both ASRS subscales) showed a highly significant positive association with the DERS scale, and correspondingly the overall ASRS was a strong independent predictor of the DERS scores. These findings confirm the hypothesis that emotional dysregulation is linked to the typical core symptoms of adult ADHD.
However, self-report measures have a number of drawbacks, and so in the second and third study, we used cognitive tasks (rather than the ASRS alone) to measure ADHD-like traits. The second study looked at the relationship between emotion dysregulation and an aspect of inattention, namely distractibility. We employed a new paradigm to measure distractibility - a modified version of the Sustained Attention to Response Test (SART), with task-irrelevant distractors on some trials. The result shows that the reaction times (RTs) on trials with distractions were faster than those without distractions, and there was no statistically significant variation depending on whether participants were in the High or Low ASRS groups. Furthermore, accuracy was higher on trials with distractors. In other words, the modified SART did not distract; instead, the distractions paradoxically helped with performance, and that facilitation did not differentially affect those with participants depending on their levels of ADHD-like traits. As a consequence, we could not draw conclusions about the relationship between emotion dysregulation and task-based inattention.
The third study looked at the relationship between emotion dysregulation and impulsivity, using two cognitive tasks: the Iowa Gambling Task and the Go-No/go Task. For the Iowa Gambling Task, both High and Low ASRS groups chose low risk strategies and there were no differences between both groups. In terms of inhibitory control, there was no statistically significant difference between groups. However, for the Go-No/go task, the difference in commission and omission error rates between the High and Low ASRS groups suggests that participants in the High ASRS group had poorer reaction inhibition (faster reaction times), and lower accuracy, indicating that the High group was sacrificing accuracy for speed. In terms of the DERS, the DERS subscales scores (clarity, goal and strategy) were associated with Go reaction times in the Low ASRS group but not in the High ASRS group. Overall, the result suggests that emotion dysregulation may not be related to the classical symptom of impulsivity, at least when the latter is measured using a cognitive task rather than a self-report scale.
The final chapter summarises the finding of this thesis, the limitation and future studies that could help to understand the relationship between emotion dysregulation and the classical symptoms of ADHD. Overall, the thesis offers evidence of some aspects of the classical symptoms of ADHD do overlap with emotion dysregulation when participants are asked to recount their experiences, but that connection is lost when ADHD-like symptoms are assessed experimentally.