# Childhood Mild Traumatic Brain Injury is Reliably Associated with Anxiety but Not Other Examined Psychiatric Outcomes at Two‐Year Follow‐up, After Adjusting for Prior Mental Health

## TL;DR

A study of over 11,000 children found that mild traumatic brain injury is reliably linked to anxiety two years later, but not to other psychiatric issues, after adjusting for prior mental health.

## Contribution

The study provides longitudinal evidence that mTBI in children is specifically associated with anxiety, after controlling for baseline mental health.

## Key findings

- mTBI in children is reliably associated with anxiety disorder diagnosis and symptoms at 2-year follow-up.
- Adjusting for baseline mental health eliminated associations with most psychiatric outcomes except anxiety.
- No consistent evidence was found linking mTBI to other psychiatric diagnoses or medication use.

## Abstract

Evidence that mild traumatic brain injury (mTBI) causes psychiatric problems in children has been mixed. Investigating this issue has been difficult due to the lack of representative longitudinal data that includes adequate measures of mTBI, subsequent mental health symptoms and service use.

We used data from the ABCD longitudinal cohort study to examine the association between mTBI and psychiatric diagnoses, symptoms and psychiatric service use in over 11,000 children. In both children reporting (i) previous mTBI at baseline and (ii) previously uninjured children reporting new cases of mTBI since baseline, we examined psychiatric outcomes and service use at 2‐year follow‐up. We also compared mTBI cases to a comparison group of participants with orthopaedic injury but without mTBI. Mixed‐effects models were used and adjusted for demographic and social covariates, with missing data imputed using random forest multiple imputation. To account for baseline mental health, we used propensity‐score matching to identify a comparison sample matched on confounding variables and baseline outcome measures.

When examined without adjustment for baseline mental health, both lifetime mTBI at baseline and new occurrence of mTBI at 2‐year follow‐up were reliably associated with an increased risk of DSM‐5 anxiety and behavioural disorders, a range of psychiatric symptom scores and increased service use. Controlling for baseline mental health in the mTBI group using propensity‐score matching eliminated all statistically reliable associations apart from anxiety disorder diagnosis and symptoms, which remain associated at 2‐year follow‐up. Evidence for association with medication use was inconsistent.

Consistent evidence supporting an association between paediatric mTBI and subsequent anxiety was found; however, similar associations were not observed for other mental health outcomes. Regardless of potential causality, children with mTBI are likely to present with high levels of mental health difficulties, and this remains an important comorbidity that clinicians should be aware of.