Evaluate cognitive performance in children with complicated mild to severe TBI using the NIH Toolbox- Cognitive Battery (NIH TB-CB), a standardized battery of cognitive tests administered on a tablet.

We recruited children ages 3–18, hospitalized at UPMC Children's Hospital of Pittsburgh with either TBI (n=218, Glasgow Coma Scale [GCS] score of 3-12 or 13-15 with abnormal neuroimaging, n=147 complicated mild TBI [cmTBI], n=68 moderate-to-severe TBI [msTBI]) or orthopedic injury (OI, n=116). Patients with spinal cord injury, prior hospitalization for TBI, premorbid neurological disorders, or premorbid psychiatric disorders requiring hospitalization were excluded. Cognitive performance was assessed at 6- and 12-months post-injury. Only a subset of participants had complete outcomes at 6-months (82 TBI, 30 OI) and 12-months (69 TBI, 32 OI). In this sample, we determined differences in cognitive performance (age- and gender-corrected T scores for Total Cognition, Fluid Cognition, and Crystallized Cognition) between children with TBI and OI using Mann-Whitney U test, as the data were not distributed normally. We also evaluated differences in cognitive performance stratified by injury severity (OI, cmTBI, msTBI), using the Kruskal Wallis test with Dunn’s post-hoc. Additionally, Spearman’s correlation was used to determine the association between initial GCS score and cognitive performance.

At 6 months, children with TBI had significantly lower Total Cognition than children with OI (TBI 46.29+11.25, OI 51.77+11.13, p=0.037, r=0.20 small). Further, children with msTBI had significantly lower Total Cognition than children with cmTBI (msTBI 40.68+8.34, cmTBI 48.22+11.67, p=0.019, ε²=0.11 moderate). For Fluid Cognition, children with TBI and OI did not differ significantly. However, children with msTBI had significantly lower scores than children with cmTBI (msTBI 38.0+10.15, cmTBI 48.34+12.81, p=0.018, ε²=0.11 moderate) and children with OI (msTBI 38.0+10.15, OI 51.12+13.01, p=0.007, ε²=0.11 moderate).  For Crystallized Cognition, children with TBI had lower scores than children with OI (TBI 45.22+8.58, OI 49.92+6.80, r =0.25 small), with no significant differences between cmTBI and msTBI (p>0.05). Children with cmTBI and children with OI did not differ on any cognitive scores at 6-months.

At 12 months, the TBI and OI groups showed no significant differences (p>0.05). However, children with msTBI had significantly lower scores than cmTBI for Total Cognition (msTBI 41.21+11.39, cmTBI 52.6+12.33, p=0.02, ε²=0.12 moderate) and Fluid Cognition (msTBI 41.18+13.40, cmTBI 41.83+12.56, p=0.039, ε²=0.08 moderate). The TBI groups showed no significant differences in Crystallized Cognition.

At six months post-injury, initial GCS score was moderately associated with Total Cognition (ρ=0.32, p=0.003) and Fluid Cognition (ρ=0.34, p=0.006). At 12 months post-injury, associations were moderate for both Total Cognition (ρ=0.44, p=0.0002) and Fluid Cognition (ρ=0.41, p=0.002).

The NIH TB-CB can detect cognitive impairments in children with more severe TBI, consistent with previous studies. These cognitive impairments are driven by poor fluid cognition, as observed in children with TBI at 12-months and in children with msTBI exclusively at 6-months. Furthermore, injury severity, as indexed by the GCS, shows moderate correlations with cognitive outcomes 6 to 12 months post-injury. Future research is needed to identify additional factors that affect individual differences in cognitive outcomes.