Understanding childhood adversity and mortality risk during adulthood

Introduction. The aim of this thesis was to explore the association between childhood adversity (CA) and mortality risk during adulthood. Adversity in childhood is a risk factor for a host of negative health associations in later life, but little is known about its complex relation with mortality risk. The thesis comprises 1) a systematic review and meta-analysis of the extant literature on childhood abuse and neglect (CAN) and its association with adult mortality risk, and 2) an empirical study investigating adverse childhood experiences (ACEs) and their differential associations with mortality risk in adulthood.

Methods. For the review, six databases were searched for studies reporting the association of adult mortality with childhood physical abuse, emotional abuse, sexual abuse, physical neglect and/or emotional neglect. When feasible, results were pooled using a random-effects meta-analysis. The empirical study utilised data from the Midlife in the United States (MIDUS) survey; an ongoing population-based longitudinal study. ACEs were assessed via self-reported exposure to 20 ACE types which formed 5 categories: physical abuse, emotional abuse, socioeconomic disadvantage, adverse family structure, and poor health at age 16 years. Mortality data was obtained via National Death Index (NDI) reports and was defined as years from baseline assessment to date of death. A series of Cox proportional hazards models were performed to assess the associations between ACEs and mortality risk.

Results. The systematic review and meta-analysis identified 9 studies which met the inclusion criteria. Types of CAN included physical abuse, emotional abuse, sexual abuse, neglect, and combined abuse and neglect. Five studies were included in the meta-analysis. Results suggest an association between CAN and adult mortality risk, along with tentative differences for males and females, but significant variability and heterogeneity was identified across studies. The empirical cohort study utilised archival data and included 6,319 participants followed for over 20 years. Results indicated ACEs were cumulatively associated with increased mortality risk. Only physical abuse remained significantly predictive of increased mortality risk when all 5 ACE categories were entered into a multivariate model. No interactions by sex or by type of adversity were found in any models.

Conclusions. The tentative associations in the review highlight the need for future rigorous research to address issues of standardised measures, representative sampling, and more detailed examination of the multi-faceted experience of CAN. Findings in the empirical study indicate ACEs are associated with increased mortality risk and that the relationship is linear in nature. Physical abuse is indicated as a risk factor over and above other adversities. The empirical data did not support sex differences in the relationship between ACEs and adult mortality risk, or interactions between adversities. Implications of this research are discussed.