Most children recover from mild traumatic brain injury (mTBI), but some experience persistent neurocognitive effects. Understanding is limited due to methodological differences and a lack of pre-injury data. The study aimed to assess changes in neurocognitive outcomes in children following mTBI compared to orthopedic injury (OI) and non-injured (NI) controls, while accounting for pre-injury functioning.

Data were drawn from the Adolescent Brain and Cognitive Development (ABCD) study, a prospective longitudinal cohort. The sample included children with mTBI between the 1-year and 2-year follow-ups (n = 83), identified by parent report of head injury with memory loss or loss of consciousness, compared to children who experienced OI within the same period (n = 231) and an NI control group (n = 218). Changes in neurocognitive outcomes from baseline to the 2-year follow-up between groups (mTBI vs. OI; mTBI vs. NI) were estimated using linear mixed-effects models, accounting for demographic, behavioral, genetic, and white matter microstructural covariates.

At baseline prior to injury, the mTBI group demonstrated better performance on picture vocabulary and crystallized composite scores than the OI group. At post-injury, after adjusting for pre-injury baseline differences, children who sustained an mTBI were no different in any measure of neurocognitive outcomes compared to OI and NI controls.

The findings highlight the importance of accounting for pre-injury differences when evaluating neurocognitive outcomes following pediatric mTBI. Neurocognitive differences within a year post-injury may be more related to pre-existing individual factors rather than the injury itself, underscoring the need for a comprehensive approach in studying pediatric mTBI.