BMI trajectories from infancy to 18 years and mental health in emerging adulthood

Background: Studies exploring early life-course BMI trajectories and subsequent mental health outcomes are limited but may provide important insights for early intervention. We investigated associations between BMI trajectories from 0 to 18 years and mental health outcomes in emerging adulthood. Methods: Data were obtained from 434 participants in the Melbourne Atopy Cohort Study (MACS). Anthropometric data were collected across 26 timepoints from infancy to age 25 and group-based trajectory modelling was used to develop BMI trajectories from 0.1 to 18 years. Moderate-to-severe psychological distress (MSPD) and likely depression were assessed at age 18 and 25 years. Associations between BMI trajectories and mental health at 25 years and change in mental health between 18 and 25 years were estimated using logistic regression. History of asthma, hay fever or eczema were independently examined as potential effect modifiers. Results: Five BMI trajectories were identified from 1 month to 18 years. When compared to the stable average BMI trajectory, we found an increased risk of MSPD (OR = 2.97; 95%CI: 1.09,8.06) and likely depression (3.56; 1.39,9.12) at age 25 in the average increasing-to-high trajectory. This group also had a greater likelihood of new-onset depression (4.82; 1.54,15.0) from 18 to 25 years of age. Limitations: MACS participants are not representative of the general population and mental health data was not available before 18 years of age. Conclusion: Excessive weight gain across the childhood transition was associated with poorer mental health in emerging adulthood, highlighting the importance of monitoring growth to allow for early identification and stratification of individuals at risk of poor mental health.