Understanding the neural basis of resilience in young people using functional neuroimaging methods

: (Alternative Format Thesis)

Abstract

Adversity exposure during childhood is associated with negative health outcomes, including a higher risk for multiple forms of psychopathology. However, not all people who experience adversity during their formative years go on to develop mental illness; instead, many will demonstrate psychological resilience. Understanding resilience in young people is important because strategies that bolster resilience to psychopathology could be used clinically, either preventatively in those at high-risk for developing a disorder due to adversity exposure, or as part of treatments for those currently suffering from a disorder. Despite this, much of the resilience literature is focused on adults; functional magnetic resonance imaging (fMRI) studies of resilience in children and adolescents, in particular, are scarce and tend to have had small samples. Thus, the current thesis aimed to examine associations between resilience and brain activation to emotional stimuli in young people using a novel dimensional approach to defining resilience.

Chapter 1 introduces the concept of resilience and reports on foundational work that shaped the field, before describing factors that have been proposed as bolstering resilience and introducing candidate neural markers identified in previous functional imaging studies. Chapter 2 is a systematic review of the current neuroimaging literature (functional, structural, and connectivity studies) on resilience in young people, using data from 22 articles identified from a search of four online databases. The review found preliminary evidence that resilience is associated with structural, functional, and connectivity differences in young people. Specifically, the fMRI literature suggests that resilience is associated with greater frontal activation and lower limbic responses to negative stimuli. In addition, greater activation in areas associated with reward, such as the ventral striatum, was also associated with resilience. The review also identified heterogeneity with regards to definitions of resilience, and common methodological issues, across the imaging literature.

Chapters 3 and 4 are functional magnetic resonance imaging (fMRI) studies that used a data-driven, dimensional measure of resilience to investigate associations between resilience and brain activation when processing facial stimuli. Chapter 3 used a conscious face processing task to examine brain responses to fearful, angry and neutral faces in young people (N=208). The results suggest that those higher in resilience showed increased activation in areas associated with cognitive control in response to emotional faces, and reduced activation in limbic areas in response to neutral faces, compared to individuals lower in resilience. Sex-by-resilience interactions were observed in the medial prefrontal cortex in response to fearful and angry faces, with males showing a positive relationship between activation and resilience, and females showing the opposite. Chapter 4 examined brain responses to subliminally presented emotional faces, to investigate resilience effects on automatic responses to emotional stimuli. In contrast to Chapter 3, which found resilience was linked to higher activation in areas associated with cognition and lower activation in limbic regions, the findings suggest that those higher in resilience showed greater activation in areas linked to both cognition and emotion. Resilience was positively associated with right supplementary motor area responses to angry faces in females, but negatively associated in males. Chapter 5 provides an overview of the thesis and discusses the main findings from each study. This chapter also describes strengths and limitations of the thesis as a whole, with discussion of the samples and methodological approaches used. Finally, Chapter 5 highlights potential future directions for neuroimaging studies of resilience.

Overall, the findings of the thesis provide evidence that youth higher in resilience recruit frontal areas when processing emotional stimuli, suggesting that they are better able to regulate their emotional responses. In addition, the thesis provides evidence that the relationship between resilience and brain activation differs between the sexes and as such, future resilience studies should take sex into account.

Date of Award	24 May 2023
Original language	English
Awarding Institution	University of Bath
Supervisor	Graeme Fairchild (Supervisor) & Catherine Hamilton-Giachritsis (Supervisor)