Obesity in childhood : psychosocial consequences and premature mortality

Background: It is estimated that 91 million children worldwide will have obesity by 2025. Obesity in childhood is associated with increased risk of obesity in adulthood, psychosocial maladjustment, mental health problems, reduced life expectancy, and several metabolic and cardiovascular complications. Most previous studies exploring the association between childhood obesity, psychosocial health, and mortality have not taken socioeconomic status (SES) into account and are based on self-reported data or small sample sizes.

Aim: This thesis focuses on short- and long-term consequences of childhood obesity. More specifically, completion of 12 or more years of schooling (Study I), anxiety- and depressive disorder in childhood (Study II), and mortality risk in young adulthood (Study III) was studied among individuals with obesity in childhood compared with a population-based comparison group. The effect of parental SES (Study I-III) and response to obesity treatment (Study I-II) on the outcomes was also examined.

Material and Method: Data was collected from the Swedish Childhood Obesity Treatment Register (BORIS, initiated in 2005), and from national registers. Data was analyzed and compared with a group from the general population matched by year of birth, sex, and area of residence. Information on parental SES and health-related variables were also collected.

Results: In Study I, 56.7% of those in the obesity cohort completed ≥12 school years compared with 74.4% in the comparison group. In both groups, children growing up in high SES households were five times more likely to complete ≥12 years of schooling than children in low SES. Nevertheless, obesity remained a strong risk factor for school completion, independently of parental SES. In Study II, children with obesity were at increased risk of anxiety and depressive disorder compared with the general population, irrespective of parental SES and other obesity-related risk factors. Girls with obesity had a 43% higher risk of anxiety and depressive disorder than girls in the comparison group. The risk was similar in boys with obesity (33%). Good response to obesity treatment was associated with lower risk of anxiety and depressive disorder (Study II), and with higher odds of completing ≥12 years of school (Study I). In Study III, risk of premature mortality was three times greater in the obesity cohort compared with the comparison group. Median (IQR) age of death was 22 (20.0-24.5) years. Low parental SES and male sex was associated with all-cause mortality. A quarter of the deaths among individuals in the obesity cohort had obesity as a primary or contributing cause of death. Suicide and self-harm were the most common causes of death in both groups.

Conclusion: This thesis shows that obesity per se is associated with lower odds to complete ≥12 school years, increased risk of anxiety and depressive disorder in childhood, and higher risk of premature mortality. The results emphasize the wide consequences that childhood obesity has on public health and stress the need of accelerated efforts to provide psychosocial support and improved obesity treatment early in life.

List of scientific papers

I. Lindberg L, Persson M, Danielsson P, Hagman E, Marcus C. Childhood obesity is negatively associated with completed educational level independent of socioeconomic status: a prospective cohort study. [Submitted]

II. Lindberg L, Hagman E, Danielsson E, Marcus C, Persson M. Anxiety and depression in children and adolescents with obesity: a nationwide study in Sweden. BMC Med. 2020; 18(1):30.
https://doi.org/10.1186/s12916-020-1498-z

III. Lindberg L, Danielsson P, Persson M, Marcus C, Hagman E. Association of childhood obesity with risk of early all-cause and cause-specific mortality: A Swedish prospective cohort study. PLoS Med. 2020; 17(3): e1003078.
https://doi.org/10.1371/journal.pmed.1003078