Chronic Stress and Child Adiposity: Testing a Bio-behavioural Model
About the Project
Chronic stress is increasingly being recognized as an important risk factor in the development of obesity. Among children as young as preschool age, exposure to chronic stress, including parental divorce, parental depression, and household chaos, has been associated with higher weight status, greater waist circumference, and excess weight gain over time. However, the mechanisms by which chronic stress causes excess weight gain and differential fat distribution among children are poorly understood. Putative behavioural mechanisms linking stress with obesity include increased consumption of energydense foods, eating for comfort, reduced physical activity, increased screen time, and poorer sleep. Research examining these mechanisms is sparse, particularly among young children. Additionally, no study has examined the relative contributions of these various behavioural mechanisms on obesity risk. Identication of the behaviours that have the strongest effect on obesity risk among chronically stressed children is needed before effective obesity prevention interventions for children who experience stress can be developed.
Biologically, a central aspect of the stress response is the activation of the hypothalamic-pituitary-adrenal (HPA) axis, which leads to increases in circulating cortisol. Prolonged elevation of cortisol leads to increased adiposity, particularly abdominal adiposity, as well as increased appetite and preferences for high-fat and high-sugar foods. Similar to the lack of research examining behavioural mechanisms, few studies have examined the association between cortisol and obesity among young children and the majority of this research has been cross-sectional. The mechanisms by which stress is linked to obesity are complex; for example, cortisol increases preference for high-fat and high-sugar foods, whereas eating these “comfort” foods buffers HPA response to stress. Thus, longitudinal research is needed to elucidate the direction of these complex pathways.
To address these key knowledge gaps, our study objective is to examine the behavioural and biological pathways through which exposure to chronic stress may impact obesity risk in children. Specifically, we will test the conceptual model that exposure to chronic stressors, i.e., household chaos, negative life events, food insecurity, and parental depression, is associated with higher adiposity among children directly and mediated through alterations in children’s behaviours, i.e., their dietary intake, eating behaviour, level of physical activity, sedentary behaviours and sleep, and their cortisol production. We will also examine the extent to which caregiver relationship quality, child sex, and family socio-economic status moderates the pathways linking stress and child adiposity.
To achieve our objective, we will conduct a longitudinal study among 300 children aged 2 to 5 years from socio-economically diverse families. Our interdisciplinary team includes experts in childhood obesity, stress, and longitudinal research design and analysis, as well as knowledge users from public health. By elucidating the mechanisms through which stress “gets under the skin” and leads to excess adiposity in children, our results will provide a much-needed basis for effective obesity prevention interventions.