Author ORCID Identifier
Year of Publication
Doctor of Philosophy (PhD)
Dr. Chizimuzo T.C. Okoli
Adverse childhood experiences (ACEs) pose a major public health issue as they are associated with poor mental and physical health outcomes. In the United States (US), more than 60% of adults report at least one ACE, and around 15% experienced four or more. Repeated exposure to ACEs stressors can convert ACEs to toxic stress by altering the brain's architecture and function. Evidence suggests that exposure to four or more ACEs, which are indicators of exposure to toxic stressors, is associated with nicotine dependence (ND) and depressive symptoms. Moreover, people with mental illnesses (MI) often have greater exposure to toxic stressors and increased vulnerabilities associated with ACEs. These vulnerabilities stand as a challenge in treatment by aggravating MI symptoms, decreasing treatment adherence, and decreasing the quality of life.
An important gap in knowledge among those living with MI is the relationship between ACEs, depressive symptoms, and ND. Individuals exposed to ACEs may be more likely to develop ND if they use smoking to cope with the adverse symptoms associated with traumatic experiences. ND, in turn, can also increase the risk of depressive symptoms. Individuals who smoke are more likely to report depressive symptoms compared to those who do not smoke and smokers with a history of depressive symptoms have a greater challenge in achieving smoking cessation. Indeed, individuals with depressive symptoms may be more likely to smoke as a form of self-medication to alleviate their symptoms. For people with depressive symptoms, nicotine can temporarily improve mood, stress, and concentration, but due to its addictive nature, the apparent dysphoric symptom alleviation is inevitably replaced with ND. These factors can create a cycle of stress, addiction, and poor mental health. Therefore, understanding both ND and depressive symptoms is important for treatment considerations for individuals who have experienced ACEs.
To understand the relationships between ACEs, ND, and depressive symptoms among people with MI, both the ACE pyramid model and the eco-bio-developmental (EBD) framework were used as conceptual frameworks to guide this study. According to the ACE pyramid model, exposure to childhood adversities can result in physical and mental health problems when an individual adopts maladaptive risk-health behaviors as coping mechanisms. In the case of the relationship between ACEs, ND, and depressive symptoms, one can extrapolate that ACEs cause fundamental changes in emotional status (e.g., depressive symptoms), leading to coping through risky behaviors (e.g., tobacco use) which then leads to ND. The EBD framework further proposes a bidirectional relationship between physical and mental illnesses and risky behaviors resulting from toxic stress (from ecological cues and biological responses) due to ACEs. In this case, for people with existing MI, ACEs increases the vulnerability to substance use (e.g., tobacco use) and the associated addiction (i.e., ND symptoms) which then leads to worsened MI symptomology (e.g., depressive symptoms). In response to these frameworks, there are two potential pathways explaining the relationships between ACEs, ND, and depressive symptoms. The first pathway suggests that for people living with MI, depressive symptoms may mediate the relationship between ACEs and ND. The second pathway suggests that for these individuals, the relationship between ACEs and depressive symptoms may be mediated by ND severity. Thus, performing a robust mediational analysis can clarify the relationship between ACEs, depressive symptoms severity, and ND.
This dissertation aims to enhance our understanding of the relationship between ACEs, ND, and depressive symptom severity among people living with MI. The specific aims are to: 1) conduct a systematic review and meta-analysis to highlight gaps in the current literature and provide directions for future research regarding the association between exposure to toxic stressors (i.e., four or more ACEs) and tobacco use behavior (e.g., tobacco use status, initiation, nicotine dependence); 2) evaluate the psychometric properties of the 10-item ACEs questionnaire for ACEs among people with MI; and 3) examine the predictive model of whether: a) ND mediates the relationship between ACEs and depressive symptom severity, or if b) depressive symptom severity mediates the relationship between ACEs and ND for people living with MI.
Aim 1 was achieved by conducting a literature search for studies that examined toxic stress (i.e., exposure to four or more ACEs) and tobacco use behaviors from the PubMed, CINHAL, and Psych Info databases. Forty-two studies were included in the analysis. The results revealed that exposure to toxic stressors was significantly associated with ever, current and former tobacco use, heavy tobacco use, tobacco use initiation, problematic tobacco use, ND, and electronic cigarette use. In a meta-analysis, the prevalence of "ever tobacco use" and "current used tobacco" was higher among people exposed to toxic stressors than those with no ACEs.
Aim 2 was achieved through a psychometric analysis (i.e., reliability and validity) of the 10- item ACEs questionnaire in a community-based sample of people with MI. The 10-item ACEs demonstrated adequate validity but poor internal consistency reliability. When using the 10-item ACEs scale, researchers and clinicians should be aware of its potentially limited reliability for people with MI.
Aim 3 was achieved by performing a series of mediational analyses to examine the relationships between ND and depressive symptom severity, considering cumulative exposure to ACEs among a community sample of people with MI. depressive symptoms mediated the relationship between ACEs and ND in the total and among males in gender-analysis stratified analysis. As compared to depressive symptoms as a mediator, ND were a stronger mediator of the relationship between ACEs and depressive symptoms in the total and among males in the gender-stratified analysis.
Given that people with MI are particularly vulnerable to ND and comorbid depressive symptoms, ACEs screening and treatment for tobacco users with MI is essential to ensure comprehensive mental healthcare. Moreover, providing dual management of ND and depressive symptoms among people with MI who have experienced ACEs may improve tobacco cessation outcomes and depressive symptoms managements in this population and improve their mental health.
Digital Object Identifier (DOI)
- Delta Psi Chapter of Sigma Theta Tau (2021)
- PhD Dissertation Research Award (2021)
Abufarsakh, Bassema, "ADVERSE CHILDHOOD EXPERIENCES, NICOTINE DEPENDENCE, AND DEPRESSIVE SYMPTOMS AMONG A COMMUNITY SAMPLE OF PEOPLE WITH MENTAL ILLNESSES" (2023). Theses and Dissertations--Nursing. 67.
Available for download on Monday, August 18, 2025