Association of Psychological Resilience, Cognitive Reserve, and Brain Reserve with Post-Concussive Symptoms in Children with Mild Traumatic Brain Injury and Orthopedic Injury: An A-CAP Study.

Protective factors, including psychological resilience, cognitive reserve, and brain reserve, may be positively associated with recovery after pediatric mild traumatic brain injury (mTBI) but are yet to be studied concurrently. We sought to examine these factors as moderators of post-concussive symptoms (PCS) in pediatric mTBI compared with mild orthopedic injury (OI). Participants included 967 children (633 mTBI, 334 OI) aged 8-16.99 years, recruited from 5 Canadian pediatric emergency departments as part of a prospective longitudinal cohort study. At 10 days post-injury, psychological resilience was measured using the Connor-Davidson Resilience Scale and brain reserve was measured using total brain volume derived from structural magnetic resonance imaging. Cognitive reserve was measured at 3 months post-injury using IQ scores from the Wechsler Abbreviated Scale of Intelligence-Second Edition. Cognitive and somatic PCS were measured using child and parent ratings on the Health and Behavior Inventory, completed weekly for 3 months and biweekly to 6 months. Analyses involved generalized least-squares regression models using restricted cubic splines. Covariates included age at injury, sex, racialized identity, material and social deprivation, pre-injury migraine and concussion history, and retrospective pre-injury PCS. Psychological resilience moderated group differences in parent-reported PCS. At 30 days post-injury, estimated group differences in parent-reported cognitive and somatic PCS (mTBI > OI) were larger at higher (75th percentile) resilience scores (Est = 2.25 [0.87, 3.64] and Est = 2.38 [1.76, 3.00], respectively) than at lower (25th percentile) resilience scores (Est = 1.44 [0.01, 2.86] and Est = 2.08 [1.45, 2.71], respectively). Resilience did not moderate group differences in child-reported PCS but was negatively associated with child-reported PCS in both groups (ps ≤ 0.001). Brain reserve (i.e., total brain volume [TBV]) also moderated group differences, but only for parent-reported somatic PCS (p = 0.018). Group difference (mTBI > OI) at 30 days was larger at smaller (25th percentile) TBV (Est = 2.78 [2.17, 3.38]) than at larger (75th percentile) TBV (Est = 1.95 [1.31, 2.59]). TBV was not associated with parent-reported cognitive PCS or child-reported PCS. IQ did not moderate PCS in either group but had a significant non-linear association in both groups with child-reported somatic PCS (p = 0.018) and parent-reported PCS (p < 0.001), with higher PCS scores at both lower and higher IQs. These findings suggest that higher resilience predicts fewer PCS, but less strongly after mTBI than OI; greater brain reserve may reduce the effect of mTBI on somatic PCS; and cognitive reserve has an unexpected curvilinear association with PCS across injury types. The results highlight the importance of protective factors as predictors of recovery and potential targets for intervention following pediatric mTBI.