CCL2 and concussion: Further sub-analysis based on timings demonstrated that blood MCP-1/CCL2 levels are particularly elevated in the acute stages in patients with mTBI compared to healthy controls (within 7 days) (SMD: 0.40 [95% CI: 0.22, 0.59] pg/mL) (p = 0.0001, I2 = 0%) (Figure 6B).