NEFL and attention deficit-hyperactivity disorder: The ADHD group exhibited a significant increase in NF-L levels at 2 h-post heading compared to baseline (0.45 pg./mL [0.05, 0.86 pg./mL], p = 0.032) but no change at 24 h-post heading (0.19 pg./mL [−0.20, 0.59 pg./mL], p = 0.340).