Sex Differences in the Joint Trajectories of Depressive Symptoms and Body Mass Index From Adolescence to Early Adulthood: Longitudinal Observational Study.

Background: Adolescence is a critical transitional period between childhood and adulthood, marked by dramatic changes in physical and psychosocial health. Adolescents are vulnerable to both depression and adiposity, but how these conditions evolve over time from adolescence to early adulthood and whether sex differences exist remains unclear.

Objective: This study aims to first identify the population heterogeneity in the joint trajectories of depressive symptoms and BMI from adolescence to early adulthood and then explore the sex differences in the joint trajectories.

Methods: In this study, we adopt the latent class trajectory modeling to identify the combined trajectories of depressive symptoms and BMI from adolescence at baseline to early adulthood at follow-ups using a longitudinal study (2010-2020). We used the multinomial logistic regressions to examine the sex-specific associations with the trajectory classifications.

Results: Our results found that individuals' depressive symptoms and BMI might not always change parallelly from adolescence to early adulthood. Instead, some individuals appeared to be prone to depressive symptoms or elevated BMI, while others were multimorbid with both of them. Moreover, our study identified a clear sex-specific pattern in the joint trajectories of depressive symptoms and BMI: the females were at a higher risk of developing depressive symptoms but remained relatively stable weight status over time (odds ratio [OR] 0.68, 95% CI 0.52-0.89), while the males were at a lower risk of developing depressive symptoms but with an increasing risk of developing adiposity over time (OR 1.83, 95% CI 1.35-2.49).

Conclusions: Depressive symptoms and BMI might not always change in parallel from adolescence to early adulthood, and there is a clear sex-specific pattern in the joint trajectories of depressive symptoms and BMI. This will inform the design of future sex-specific interventions that match the distinguished profiles in male and female participants during the period of adolescence and early adulthood, respectively, thus maximizing the intervention effects in preventing both depression and adiposity in early life.