Mild Traumatic Brain Injury and Criminal Charges and Convictions in Mid and Late Adolescence.

Importance: Childhood exposure to mild traumatic brain injury (mTBI) is common. Individuals with a childhood history of mTBI experience more frequent criminal justice involvement in mid to late adolescence and adulthood. No study had been conducted to examine whether the link is causal or spurious.

Objective: To determine whether mTBI in childhood causes criminal justice involvement in mid to late adolescence.

Design, setting, and participants: This cohort study used population-based data for all children born between 1995 and 2000 in Denmark, with data linked to emergency department (ED) visits and hospitalizations before age 10 years and all criminal charges and convictions from ages 15 to 20 years. The exposure group contained all individuals diagnosed with mTBI before age 10 years without other intracranial or extracranial injuries; the comparison group was individuals not diagnosed with mTBI or intracranial or extracranial injuries. Sibling and twin fixed-effects models were used to evaluate the association after controlling for family-level confounding. Data were analyzed from May 2021 to July 2024.

Exposures: Mild TBI before age 10 years without other intracranial or extracranial injuries before or at the time of diagnosis.

Main outcomes and measures: Associations between mTBI before age 10 years and criminal charges and convictions from ages 15 to 20 for the entire study population and separately by sex at birth, controlling for additional covariates.

Results: The final analytic sample consisted of 343 027 individuals, 13 514 in the exposure group and 329 513 in the comparison group. Of the total sample, 166 455 (49%) were female and 176 572 were male (51%). A total of 326 191 participants (95%) had at least 1 parent with Danish citizenship, and 79 386 mothers (23%) held a college degree. There was a positive association between mTBI and criminal charges (odds ratio [OR], 1.26; 95% CI, 1.19-1.34) and convictions (OR, 1.24; 95% CI, 1.16-1.33). When controlling for family-level confounding, the associations became statistically insignificant and, in most models, greatly reduced. Results were robust across multiple model specifications.

Conclusions and relevance: This study found that although mTBI in childhood was predictive of adolescent criminal justice involvement, there was no evidence that mTBI caused criminal charges or convictions.