Early life adversity and obesity risk in adolescence: a 9-year population-based prospective cohort study

Background
There are few prospective studies of factors that mediate the association between exposure to adverse childhood experiences (ACEs) and obesity in adolescence. Our aim was to address this limitation.

Methods
We used prospective data from the Growing up in Ireland cohort study, with measurements at 9, 13, and 18 years old. The exposures were 14 adverse experiences before age 9. The main outcome was body mass index (BMI) at 18 years. Mediators were daily activity, diet quality, self-image and behavioural difficulties at 13 years.

Results
Among the 4561 adolescents in the final cohort, 77.2% experienced any adversity, 50.5% were female and 26.7% were overweight/obese at 18 years. BMI Z was higher at ages 9 (0.54 vs 0.43, p < 0.05, 95% CI of difference: −0.22, −0.01) and 13 years (0.50 vs 0.35, p < 0.05, 95% CI of difference: −0.25, −0.06), in those exposed to an ACE, compared to those unexposed. Structural equation models revealed that behavioural difficulties (β = 0.01; 95% CI: 0.007–0.018, p < 0.001) and self-concept (β = 0.0027; 95% CI: 0.0004–0.0050, p = 0.026) indirectly mediate the association between exposure to ACEs and BMI at 18 years.

Conclusions
The association between ACEs and BMI in adolescence is mediated by behavioural difficulties and self-concept.

Impact

• In a previous study, we found modest associations between exposure to a range of adverse childhood experiences and weight gain at 13 years of age.
• The strength of the association between adverse childhood experiences and weight gain was lower at 18 years of age compared to the association observed at 13 years and was no longer significant after controlling for confounding and including possible mediators.
• The association between adverse childhood experiences and BMI in adolescence is indirectly mediated by behavioural difficulties and self-concept.