Associations Between Brain Metabolites Measured With MR Spectroscopy and Head Impacts in High School American Football Athletes

Background

While changes in brain metabolites after injury have been reported, relationships between metabolite changes and head impacts are less characterized.

Purpose

To investigate alterations in neurochemistry in high school athletes as a function of head impacts, concussion, and the use of a jugular vein compression (JVC) collar.

Study Type

Prospective controlled trial.

Subjects

A total of 284 male American football players, divided into JVC collar and noncollar groups; 215 included in final analysis (age = 15.9 ± 1.0 years; 114 in collar group).

Field Strength/Sequence

3 Tesla/T₁-weighted gradient echo, ¹H point resolved spectroscopy, acquired between August and November 2018.

Assessment

Head impacts were quantified using accelerometers. Concussion was diagnosed by medical professionals for each team. Pre- to postseason differences in total N-acetylaspartate (tNAA), total choline (tCho), myo-inositol (myoI), and glutamate + glutamine (Glx), in primary motor cortex (M1) and anterior cingulate cortex (ACC), relative to total creatine (tCr), were determined.

Statistical Tests

Group-wise comparisons were performed using Wilcoxon signed-rank, Friedman's, and Mann–Whitney U tests. Relationships between ∆metabolite/tCr and mean g-force were analyzed using linear regressions accounting for concussion and JVC collar. Significance was set at P ≤ 0.05.

Results

In participants without concussion, a significant decrease in tCho/tCr (0.233 ± 1.40 × 10⁻³ to 0.227 ± 1.47 × 10⁻⁷) and increase in Glx/tCr (1.60 ± 8.75 × 10⁻³ to 1.63 ± 1.08 × 10⁻²) in ACC were observed pre- to postseason. The relationship between ∆tCho/tCr in M1 and ACC and mean g-force from >80 g to >140 g differed significantly between participants with and without concussion (M1 β ranged from 3.9 × 10⁻³ to 2.1 × 10⁻³; ACC β ranged from 2.7 × 10⁻³ to 2.1 × 10⁻³). Posthoc analyses revealed increased tCho/tCr in M1 was positively associated with mean g-force >100 g (β = 3.6 × 10⁻³) and >110 g (β = 2.9 × 10⁻³) in participants with concussion. Significant associations between $∆\text{myoI}/\mathrm{tCr}$ in ACC and mean g-force >110 g (β = −1.1 × 10⁻³) and >120 g (β = −1.1 × 10⁻³) were observed in the collar group only.

Data Conclusion

Diagnosed concussion and the use of a JVC collar result in distinct neurochemical trends after repeated head impacts.

Level of Evidence

2

Technical Efficacy

Stage 3