Synchrony between brain age and internalising and externalising symptoms across adolescence.

BACKGROUND

Adolescence is a period of rapid neurobiological and behavioural change, yet it remains unclear how deviations from normative brain maturation relate to the development of internalising and externalising symptoms.

METHODS

Using data from the Adolescent Brain Cognitive Development (ABCD) Study, we combined brain age prediction with bivariate latent growth curve (BLGC) models to test whether deviations in brain maturation - indexed by the brain age gap (BAG) - relate to mental health development across late childhood and adolescence. Brain age was estimated using T1-weighted, diffusion (dMRI), resting-state fMRI, and multimodal MRI data across four waves (ages ~8.3-17.5). Internalising and externalising symptoms were assessed across ten waves with the self-report Brief Problem Monitor (BPM).

RESULTS

Across T1, dMRI, and multimodal models, deviations from age-expected brain maturation and internalising and externalising symptoms showed coordinated nonlinear development across adolescence. Adolescents whose brains increasingly diverged from age-expected maturation over time also showed increasing symptom trajectories. These associations were small to moderate in magnitude and were most consistent for internalising symptoms in females (r = .15-.23), whereas externalising symptoms showed broader but less selective nonlinear associations across modalities in both males and females (r = .15-.23). Intercept-level associations were weaker and modality-specific (r = .06-.11). Formal tests provided no evidence for robust sex differences in these associations after correction for multiple comparisons.

CONCLUSION

These results indicate that adolescent development of mental health problems is more strongly linked to nonlinear changes in how individuals diverge from age-expected brain trajectories, rather than to fixed differences in brain age. Shifts in brain maturational tempo may therefore be a key feature underlying vulnerability to psychopathology in youth.