Movement as Medicine: The Moderating Effect of Physical Activity on the Mental Health of Adolescents Impacted by a Childhood Traumatic Brain Injury

Abstract

Research has demonstrated a positive relationship between traumatic brain injuries (TBIs), mental illness, and physical activity, though much of this work has been cross-sectional or limited in follow-up. The current study used longitudinal data from the Adolescent Brain Cognitive Development (ABCD) study to explore the long-term effects of childhood TBI on adolescent mental health, specifically symptoms of anxiety and depression. This study addressed three research questions: (1) Are childhood TBIs associated with increased symptoms of anxiety in adolescence? (2) Are childhood TBIs associated with increased symptoms of depression in adolescence? (3) Does physical activity moderate the relationship between childhood TBI and symptoms of anxiety and depression in adolescence? Data from 8,374 participants were analyzed. Correlation and moderation analyses were conducted to assess associations between TBI and mental health outcomes, and the moderating role of physical activity. Correlational analyses revealed that childhood TBI was weakly but significantly associated with higher anxiety and depression symptoms. Physical activity was weakly associated with lower symptoms of both. Moderation analyses showed that physical activity did not significantly moderate the relationship between TBI and either mental health outcome. However, TBI and physical activity were each significant independent predictors: TBI was associated with greater symptom severity, while higher physical activity was associated with fewer symptoms overall. These findings suggest that while physical activity may broadly support adolescent mental health, it does not buffer the specific effects of childhood TBI. This underscores the need for early intervention and continued investigation into long-term outcomes.