Postconcussion physical activity frequency and plasma biomarker associations among adolescents

Existing studies have reported the utility of plasma biomarkers for concussion diagnosis and outcome prognostication. In parallel, physical activity (PA) after concussion is associated with better outcomes. Therefore, this study sought to investigate the association between PA frequency and plasma biomarker concentration levels following concussion.

The authors performed a cross-sectional analysis of adolescents diagnosed and evaluated within 21 days of a concussion. Participants self-reported engagement in PA as well as PA frequency since injury and underwent venipuncture. To account for variability in evaluation time, PA frequency was calculated as the percentage of days between concussion and initial evaluation in which PA was reported. Plasma analysis assays included glial fibrillary acidic protein (GFAP), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), total tau, and neurofilament light chain (NF-L).

A total of 57 adolescents participated, including 32 who reported participating in PA (mean age 15.9 [SD 1.7] years, 44% female, mean 13.0 [SD 3.8] days postinjury) and 25 who did not (mean age 15.5 [SD 1.4] years, 68% female, mean 10.6 [SD 3.6] days postinjury). Postconcussion PA frequency across the cohort was 29.3% (SD 23%, mean 3.6 [SD 3.0] days of PA since injury). A higher percentage of PA days postconcussion was associated with significantly lower levels of plasma GFAP (β = -0.52, 95% confidence interval [CI] -0.96 to -0.07; p = 0.02) and NF-L (β = -0.81, 95% CI -1.59 to -0.03; p = 0.04) after adjusting for age, sex, and symptom severity. Log-transformed coefficients indicated that for every 10% increase in the percentage of PA days since concussion, GFAP levels decreased by approximately 5.1% and NF-L levels decreased by approximately 7.9%.

These results indicate that more frequent PA in the days after concussion was associated with decreased levels of two biomarkers, GFAP and NF-L. Given the relevance of plasma biomarkers as indicators of neurobiological cell damage and ongoing repair processes after concussion, these findings suggest that postconcussion PA is associated with improved biological as well as clinical recovery outcomes.