33 Osteopontin as a Blood Biomarker for Executive Function Outcomes in Pediatric Traumatic Brain Injury
Authors: Mauer Ezra , Sayeed Iqbal , Reisner Andrew , Blackwell Laura 
Published: December 2023

Objective:Executive function (EF) is a self-regulatory construct well-established as a predictor of long-term academic achievement and socioemotional functioning in children (Best et al., 2009; Diamond, 2013; Zelazo & Carlson, 2020). Traumatic brain injury (TBI) in childhood frequently results in EF deficits (Beauchamp & Anderson, 2013; Levin & Hanten, 2005). In comparison to adults (Okonkwo et al., 2013), there is an absence of viable blood biomarkers for pediatric TBI to assist in diagnosis and prognosis. Osteopontin (OPN), an inflammatory cytokine, has recently been identified as a putative pediatric TBI blood biomarker (Gao et al., 2020). However, more work is needed to establish OPN’s utility in predicting functional outcomes. Thus, the present study aimed to test relations between OPN measured during the first 72 hours of hospitalization and EF 6-12 months post injury among a sample of pediatric TBI patients.Participants and Methods:Sample consisted of 38 children (age at injury = 4.60-16.67 years, M age = 10.61 years, 65.8% male, lowest Glasgow Coma Scale [GCS] score = 3-15, M gcs= 9.97) with TBI whose parents completed the Behavior Rating Inventory of Executive Function, Second Edition (BRIEF-2; Gioia et al., 2015) 6-12 months post injury. Plasma OPN was measured at hospital admission, 24 hours after admission, 48 hours after admission, and 72 hours after admission. 7-scores for each BRIEF-2 clinical scale (Inhibit, Self-Monitor, Shift, Emotional Control, Initiate, Working Memory, Plan/Organize, Task-Monitor, Organization of Materials) and composite index (Behavior Regulation Index, Emotion Regulation Index, Cognitive Regulation Index, Global Executive Composite) were used in analyses.Results:Correlation analyses revealed large positive associations (rs = .50-.73, ps = <.001.039) between 48-hour OPN and all BRIEF-2 scales/indices except Initiate. OPN at 24 hours positively correlated with Task-Monitor (r = .40, p = .037). Bivariate logistic regression analyses testing whether OPN predicted at least mildly elevated BRIEF-2 t-scores (>60) did not yield significant associations. Additional supplementary analyses testing whether alternative injury markers - glial fibrillary acidic protein (GFAP), ubiquitin C-terminal Hydrolase-L1 (UCH-L1), S100 calcium binding protein B (S100B) - measured at all time points as well as lowest GCS score correlated with EF revealed the following: admission S100B positively correlated with Inhibit (r = .34, p = .045), 48-hour UCH-L1 negatively correlated with Initiate (r = -.49, p = .041) and Cognitive Regulation Index (r = -.48, p = .044), and 72-hour UCH-L1 negatively correlated with Initiate (r = -.47, p = .048).Conclusions:Findings showed higher OPN at 48 hours post admission was broadly related to worse parent-reported EF 6-12 months later, with 24-hour OPN also showing limited associations. Higher levels of alternative injury markers likewise showed limited associations with EF outcomes. Null logistic regression findings may be due to few participants having elevated BRIEF-2 scores. Disrupted EF development may be more noticeable after longer time periods as children age and self-regulatory demands increase. Overall, OPN was found to more consistently predict EF outcomes than GCS score and other injury markers. This could be because OPN is a marker of inflammation, which may be particularly predictive of TBI cognitive outcomes.