EXPLORATION IN THE BIOPSYCHOSOCIAL MODEL OF STRESS AND MENTAL HEALTH AND ILLNESS: RISK FACTORS, MODERATORS, MEDIATORS AND IMPACTS
Stress has a profound impact on the brain and body in life. Stressors can lead to a wide range of adverse short- and long-term mental health problems, such as depression, post-traumatic stress disorder, anxiety, and reduced cognitive functioning. The biopsychosocial model proposed by Engel incorporates both biological and psychosocial factors and focuses on genetic predispositions, and environmental factors which play a crucial role in the process of individual’s development across the life span. The primary goal of this thesis is to better understand the relationship between social stress and mental disorders with the application of a variety of epidemiological techniques using a variety of data sources. This thesis is composed of eight chapters. The first introductory chapter describes the biopsychosocial perspective. The second chapter describes the data sources and methods used in the five substantive studies reported in each of the following chapter. The first substantive study (Chapter 3) using a population-based survey examined the rural-urban differences in the experience of abuse during pregnancy in Canada. The study findings indicated that living in an urban environment was associated with a slightly increased risk of experiencing abuse around the time of pregnancy. In addition, being aboriginal, young, unmarried, economically disadvantaged, a non-immigrant, and having more than four pregnancies, as well as cigarette smoking, alcohol drinking and drug use before the pregnancy were correlated with the abuse around the pregnancy. Postnatal depression and stressful life events were also found to be associated with the abuse experience around the time of pregnancy both in urban and rural areas. Using a cross-sectional study design, our second study (Chapter 4) investigated the mediating roles of social support and positive coping skills in the relationships between childhood maltreatment and both psychological distress and positive mental health in a national Canadian population sample. Social support and positive coping skills were both found partially mediated the negative consequences of childhood maltreatment on mental health outcomes with coping skills having a greater impact on positive mental health. No sex differences were observed among these associations. In the third study (Chapter 5), the dynamic relationships between income and self-perceived mental health were explored in a longitudinal prospective community study at both population level and individual level. The effect of income on the self-perceived mental health was only found at population level. In addition, correlations between income and self-perceived mental health were significant among different sex and age groups only at population level, with stronger effects of income in men and older adults. The fourth study (Chapter 6), a systematic review and meta-analysis of prospective longitudinal studies, found that the maternal experience of childhood maltreatment had a small but significant effect on the offspring’s depression and internalizing behaviors. Maternal depression and ethnicity were found to be the moderators among this relationship. Maternal depression reduced the effect size of the impact of maternal maltreatment on offspring’s depression and internalizing disorders. The offspring of non-Caucasian mothers who themselves had childhood maltreatment experience had a higher risk of mental disorders. With the biopsychosocial model framework, the final study (Chapter 7), a systematic review with meta-analysis and qualitative analyses, found that low birth-weight, premature birth, small gestational age, maternal education, socioeconomic status, having young parents (<20 years), having older parents (≥35 years), maternal smoking, paternal smoking, maternal stress, maternal anxiety, and maternal prenatal depression significantly increased the risk of depression in offspring. The final Chapter 8 summarizes our findings and conclusions. The key takeaway message of this research is that various stress across the life span has an adverse impact on the mental health well-beings. And stress-related factors, including biological factors, social factors and psychological factors (external and internal personal resources) both separately or combined contribute to mental disorders. Also evident is the impact of early life experiences on adult mental health. From a public health prevention perspective attention needs to be paid to the healthy pregnancies and an emotionally healthy childhood and adolescence.
Stress, mental health, mediator, moderator, biopsychosocial model
Doctor of Philosophy (Ph.D.)
School of Public Health