Changes in body mass index and risk of adolescent psychopathology: a longitudinal cohort study

Abnormal body mass index (BMI) has been associated with development of psychopathology. This association in children is well documented, for both overweight and underweight children. However, the association between change in BMI and the development of psychopathology has been less investigated. To investigate the association between change in BMI between childhood and adolescence and psychopathology in adolescence. Data from the Growing Up in Ireland cohort were used. We investigated the '98 cohort (also known as the child cohort) at age 9/13. BMI, defined using internationally recognised definitions as underweight, healthy or overweight, was used as the exposure, and abnormal Strength and Difficulties Questionnaire scores were used as the outcome. Logistic regression was undertaken for the analysis. All analyses were adjusted for confounders. A change to overweight from healthy BMI was significantly associated with increased risk of psychopathology (adjusted OR 1.66; 95% CI 1.19-2.32). Both change from underweight to healthy (adjusted OR 0.12; 95% CI 0.03-0.43) or from overweight to healthy (adjusted OR 0.47; 95% CI 0.79-0.8) was associated with a significantly reduced risk of developing psychopathology. As a child's BMI returns to within the healthy range, their risk of adolescent psychopathology is reduced. Interventions to restore healthy BMI, in both underweight and overweight, children may reduce their risk of adolescent psychopathology.