INVESTIGATING THE ASSOCIATION BETWEEN INCOME INEQUALITY AND MENTAL HEALTH AND DEATHS OF DESPAIR IN CANADIAN YOUTH

• Author / Creator

  Benny, Claire

• Rationale: Over the past two decades, both income inequality and adverse mental health in youth have increased in Canada. Income inequality is defined as the gaps between highest earners and lowest earners within a given group or area. Some research indicates that income inequality is associated with worsened mental health. Alongside this, all-cause mortality has risen greatly, as with disability-adjusted life years, likely driven in part by marked increases in deaths attributed to suicide, drug overdose, and alcohol-related liver disease, collectively known as ‘deaths of despair’. Given that adverse mental health is a risk factor for deaths of despair, it is possible that income inequality may drive increases in both mental health conditions, such as depression and anxiety, and risk for deaths of despair especially amongst young people. Previous studies have primarily been cross-sectional or ecological, and no previous research has examined the association between income inequality and deaths of despair, thus limiting our understanding of these potential associations. Furthermore, both income inequality and mental health conditions may be exacerbated during the COVID-19 pandemic, as such it is important to assess the association between income inequality and mental health in youth during COVID-19.

  Objectives: The overarching goals of the thesis are to investigate the role of income inequality and mental health conditions, such as depression and anxiety, and risk for deaths of despair in Canadian youth. Four investigations informed this goal, testing the following hypotheses: 1) that income inequality is associated with depression and anxiety over time in school-aged sample of adolescents; 2) psychosocial well-being and social cohesion may mediate the relationship between income inequality and adolescent depression; 3) that the association between income inequality and adolescent depression and anxiety was amplified during COVID-19; and, 4) that income inequality in youth is associated with an increased risk of deaths of despair, or those deaths owing to suicide, drug overdose, and alcohol-related liver disease, over time.

  Methods: Two large cohorts of youth were sampled to address these objectives, including
  Cannabis, Obesity, Mental health, Physical activity, Alcohol, Smoking, and Sedentary behaviour (COMPASS), the Canadian Census Health and Environment Cohort Profile (CanCHEC) from 2006 and 2016. Latent growth curve modelling techniques were applied to address objectives 1 and 3, cross-sectional multilevel path analyses were applied for objective 2, and multilevel survival analyses were applied for objective 4.

  Results: Analyses addressing the objectives of this thesis showed that, according to results from the linear mixed models employed in objective 1, CD-level income inequality was associated with an increase in z-transformed adolescent depressive scores (ß=0.08; 95% CI = 0.02, 0.14) and was not significantly associated with a change in z-transformed adolescent anxiety scores. Results from the multi-level path analysis employed to assess objective 2 indicated that students attending schools in CDs with higher income inequality reported higher depression scores among Canadian secondary students (ß = 5.36; 95% CI = 0.74, 9.99) and lower psychosocial well-being (ß = -14.83, 95% CI = -25.05, -4.60). For objective 3, adjusted, linear mixed models demonstrated that the association between income inequality and anxiety scores was significantly exacerbated following the onset of COVID-19 (ß =0.02, 95% CI=0.0004, 0.03), indicating that income inequality was associated with a greater increase in anxiety scores during COVID-19, as compared to before COVID-19. Finally, the results of assessing objective 4 of this thesis showed that a SD-unit increase in Gini coefficient was associated with an increase in the hazard ratio for deaths of despair [adjusted hazard ratio (aHR): 1.35; 95% CI: 1.04, 1.75], drug overdose (aHR: 2.38; 95% CI: 1.63, 3.48), and all-cause deaths (aHR: 1.10; 95% CI: 1.04, 1.18).

  Conclusion: The findings from this thesis highlight associations between income inequality and adolescent depression and anxiety (particularly during COVID-19), and deaths of despair in youth. This work can inform programs and policies for reducing income inequality, improving youth mental health, and reducing the risk of deaths of despair amongst young Canadians, particularly during a public health crisis, such as a global pandemic.

• Subjects / Keywords

  • income inequality
  • mental health
  • substance use
  • deaths of despair
  • depression
  • anxiety
  • adolescents
  • social epidemiology

• Graduation date

  Spring 2023

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-8062-z371

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.