# Longitudinal co‐development of mental and cardio‐metabolic health from childhood to young adulthood

## TL;DR

This study shows that mental health and body fat levels influence each other over time in young people, with body fat having a stronger effect on future mental health.

## Contribution

The study reveals bidirectional, longitudinal associations between depressive symptoms and adiposity in youth, with adiposity showing stronger predictive power.

## Key findings

- Depressive symptoms and adiposity (fat/lean mass index) are bidirectionally linked over time.
- Adiposity has a stronger prospective association with future depressive symptoms than vice versa.
- The strongest associations occur between ages 14 and 16.

## Abstract

Depressive symptoms and cardio‐metabolic risk factors often co‐occur. However, our understanding of the potential mechanisms and temporal dynamics underlying their co‐development remains elusive.

This population‐based cohort study examined bidirectional longitudinal associations between depressive symptoms and cardio‐metabolic risk factors from age 10 to 25 years, using prospective data from the ALSPAC Study. Participants with at least one (of six) follow‐up measurement for each outcome were included in the analyses. We measured depressive symptoms through self‐ as well as parent‐reports, and assessed several cardio‐metabolic risk factors (including adiposity measures, lipid profiles, and inflammation).

Among our 7,970 (47% male, 96% White) participants, we found bidirectional, within‐person associations between self‐reported depressive symptoms and adiposity (i.e., fat/lean mass index, but not body mass index), across the study period. Adiposity was more stable over time (β [range] = 0.75 [0.54; 0.84]), compared to depressive symptoms (0.26 [0.12; 0.38]), and it had a stronger prospective (i.e., cross‐lagged) association with future depressive symptoms (0.07 [0.03, 0.13]) compared to that between depressive symptoms and future adiposity (0.04 [0.03, 0.06]). The magnitude of these associations reached its peak between 14 and 16 years. We did not find evidence of cross‐lagged associations in either direction between depressive symptoms and waist circumference, insulin, triglycerides, LDL cholesterol, or C‐reactive protein.

These findings suggest a bidirectional relationship between depressive symptoms and cardio‐metabolic risk factors, particularly adiposity (i.e., fat/lean mass). Adiposity showed a stronger prospective association with future depressive symptoms than vice versa; however, their relationship revealed more reciprocal than previously thought.