The Influence of Childhood Cognitive Abilities on Adult Health and Socioeconomic Outcomes in Extremely Low Birth Weight Survivors

Abstract

Objectives: The purpose of this thesis is to explore the associations between childhood cognitive abilities assessed at age 8 and health and socioeconomic outcomes at age 29-36 in extremely low birth weight survivors (ELBW, <1000g). Methods: Using data from the McMaster Extremely Low Birth Weight Cohort Study, Study 1 explores the influence of overall intelligence, fluid intelligence, and language abilities on the prevalence of lifetime major depressive disorder in ELBW survivors and normal birth weight comparison subjects. Study 2 examines the mediating role of overall intelligence, fluid intelligence, language abilities, quantitative reasoning, and academic achievement on the association between being born at ELBW and socioeconomic outcomes at age 29-36. The final study examines the moderating role of childhood cognitive functioning on links between postnatal psychosocial adversity and adult personal earnings in ELBW survivors. Results: Results from Study 1 suggest that childhood cognitive abilities do not influence the onset of major depressive disorder in ELBW survivors, but are protective against depression in normal birth weight individuals. Study 2 suggests that childhood cognitive abilities partially mediate the association between being born at ELBW and income attainment in adulthood, but not full time employment. Further, Study 2 suggests that this association is stronger in ELBW survivors who have neurosensory impairments. Results of Study 3 suggest that enhanced childhood cognitive functioning is not protective against postnatal psychological adversity in influencing income attainment, as those ELBW survivors with higher childhood intelligence and who suffered psychological adversity reported lower annual income at age 30. Conclusions: This thesis suggests that overall and specific cognitive abilities significantly influence adult outcomes in ELBW survivors and normal birth weight individuals. However, while cognitive reserve may not be protective against psychological adversity in ELBW survivors, early cognitive abilities are a critical indicator of socioeconomic attainment in this vulnerable population.