Early life adversity (ELA) has been a major focus of research on the etiology of various adverse mental health outcomes, including internalizing symptoms and self-harm/suicidal behaviors, in children and adolescents. However, the frameworks under which ELA has been defined and categorized has varied widely across studies. Also, although alterations in the inflammatory arm of the immune system have been postulated as a potential biological mechanism through which ELA perpetuates the risks of adverse health outcomes, whether or not systemic inflammation mediates the association between ELA exposure and internalizing symptoms and self-harm behaviors in young people remains to be tested. Finally, as not all individuals exposed to ELA develop adverse outcomes, more is yet to be learned with regard to the potential resilience factors which may offset the negative impact of ELA.
In the present thesis, I proposed the ecological system model of ELA, which views ELA exposed individuals as embedded within layered environments: the immediate environment (Individual-level) and the extrinsic environment (Area-level). The thesis examined the roles of and the interplay between Individual-level ELA (with a special focus on the family context) and Area-level ELA (with a special focus on the neighborhood deprivation) on the development of internalizing symptoms, self-harm behaviors and suicidality in young people. In addition, the thesis investigated the role of systemic inflammation on the relationships between ELA exposure and internalizing symptoms and self-harm in adolescents. Finally, the thesis explored the roles of high physical activity level, high perceived social support level, and high intelligence as potential resilience factors, and tested their protective effects in buffering the impact of ELA exposure against the development of internalizing symptoms and self-harm behaviors in adolescents, as well as in their relation with systemic inflammation.
The thesis is comprised of 4 studies, which explored the following topics in order:
1) the role of the socioeconomic aspect of the family context (as indicated by parental educational level) on suicidality in young people (Chapter 2);
2) the role of the relational aspect of the family context (as indicated by fragmentation-related life events occurring within the family environment) on suicidality in young people (Chapter 3);
3) the roles of and the interplay between Individual-level and Area-level ELA on internalizing symptoms and self-harm behaviors in young people (Chapter 4);
4) the role of systemic inflammation on the relationship between ELA and internalizing symptoms and self-harm behaviors in young people (Chapter 5);
5) the role of physical activity level, perceived social support, and intelligence quotient (IQ) on the relationships between ELA and A) internalizing symptoms and self-harm behaviors and B) systemic inflammation in young people (Chapter 4 & 5).
Chapter 2 used a systematic review and meta-analytical approach to synthesize the existing evidence on these relationships. Chapter 3 was an analysis performed on data from the international multi-center cohort study IMAGEN. Chapter 4 and 5 were primary analyses performed using the baseline data of the prospective longitudinal London-based study eBRAIN of community adolescents.
Using the meta-analytical approach and the data across the two cohort studies (IMAGEN & eBRAIN), we found that Individual-level ELA, specifically the family-context type, is associated with higher risk of adolescent internalizing symptoms, self-harm behaviors, and suicidality. High levels of physical activity and perceived level of social support were found to be potential resilience factors. However, our findings reject the role of systemic inflammation as the mediator between Individual-level ELA and adolescent psychopathology during adolescence. Interestingly, our findings provide evidence of an interactive effect between Individual-level and Area-level ELA on adolescent inflammatory profile, as well as of modulating effects of IQ levels on adolescent inflammatory profile.
The current findings provide preliminary evidence on the roles and the interplay between Individual-level and Area-level ELA on the development of clinically significant internalizing symptoms and self-harm/suicidal behaviors in young people, and highlight the importance of family context in the early period of life. These findings have important clinical implications for mental health promotion and self-harm/suicide prevention in youths.
Furthermore, the findings found no evidence supporting the hypothesis of systemic inflammation mediating the relationships between ELA and internalizing symptoms and self-harm behaviors in adolescents, suggesting that this possible biological mechanism linking ELA exposure to adverse health outcomes may become apparent only later in life. The findings also add to the literature on the moderating roles of Area-level deprivation and IQ levels on the inflammatory profile in Individual-level ELA exposed young people, inviting future investigations on potential mechanistic pathways.
|Date of Award||1 Jul 2023|
|Supervisor||Paola Dazzan (Supervisor) & Chiara Nosarti (Supervisor)|