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Inequitable urban environments are associated with toxic stress and altered neural social stress processing that threatens the development of self-regulation. Some children in these environments struggle with early onset externalizing problems that are associated with a variety of negative long-term outcomes. While previous research has linked parenting daily hassles to child externalizing problems, the role of frontal alpha asymmetry (FAA) as a potential modifier of this relationship has scarcely been explored. The present study examined mother-child dyads, most of whom were living in low socioeconomic status households in an urban environment and self-identified as members of racial minority groups. Analyses focused on frustration task electroencephalography (EEG) data from 67 children (mean age = 59.0 months, SD = 2.6). Mothers reported the frequency of their daily parenting hassles and their child’s externalizing problems. Frustration task FAA moderated the relationship between parenting daily hassles and child externalizing problems, but resting FAA did not. More specifically, children with left frontal asymmetry had more externalizing problems as their mothers perceived more hassles in their parenting role, but parenting hassles and externalizing problems were not associated among children with right frontal asymmetry. These findings lend support to the motivational direction hypothesis and capability model of FAA. More generally, this study reveals how individual differences in lateralization of cortical activity in response to a stressor may confer differential susceptibility to child behavioral problems with approach motivation (i.e., left frontal asymmetry) predicting externalizing problems under conditions of parental stress.

Background: Emotion regulation is the ability to modulate behavioural responses to emotion-inducing stimuli in a goal directed manner. When emotion regulation processes become maladaptive, it results in emotion dysregulation (ED). ED is present in 25-45% of children with psychiatric disorders and strongly predicts poor clinical outcomes. ED presents as elevations in comorbid internalizing and externalizing symptoms. The relative contributions of these heterotypic comorbidities to ED in a particular patient is unclear. Clinicians must prioritize treatment of either domain of symptoms without empirical evidence. Objective measures of ED would assist in guiding treatment decisions. This thesis aimed to explore the biological correlates of ED with a focus on associations between ED and electroencephalographic (EEG) asymmetry. A secondary aim was to explore whether these relationships differed in populations with mood versus behavioural disorders. Methods: A systematic review was conducted to qualitatively evaluate present literature on ED and its biological correlates. The relationship between frontal and parietal EEG asymmetry and ED, measured by the child behaviour checklist – dysregulation profile, was assessed in a secondary analysis of the D-Psypher dataset with a transdiagnostic sample of 88 adolescents with varying severity of psychopathology and risk for ED. Relationships were assessed in the whole sample, and according to the following groups: depression only, depression comorbid with a behavioural disorder, and controls. Results: The systematic review included 12 studies and found ED-related differences in neural, cardiac, and genetic measures. The second study found associations between right parietal EEG asymmetry and ED in the whole sample and in youth with depression only. In youth with comorbid depression, ED was associated with left frontal asymmetry. Conclusion: This thesis outlines several findings related to the biological correlates of ED in adolescents. Understanding how these correlates differ in various disorder categories has important implications for the measurement and treatment of ED. Thesis Master of Science (MSc) Emotion dysregulation (ED) is a transdiagnostic feature of psychopathology that presents as elevations in comorbid internalizing and externalizing symptoms and/or disorders; however, it is unknown whether ED may manifest more prominently from externalizing versus internalizing brain process. A neural measure of ED would help differentiate between these processes. Thus, the first study in this thesis synthesized the available literature on biological correlates of ED and found evidence for differences in neural correlates involved in mood versus behavioural disorders. The second study explored correlations between frontal and parietal electroencephalographic asymmetry and ED in a transdiagnostic sample of youth and compared youth with major depressive disorder (MDD) only to youth with MDD comorbid with oppositional defiant disorder (ODD) or disruptive mood dysregulation disorder (DMDD) and controls. Findings of this thesis suggest differences in neural processes underlying ED in different disorder categories, which has important implications for the measurement and treatment of ED.