For children and adults who were not currently on ADHD medication, Synbiotic 2000 suggestively increased the levels of VEGF-A (children: 95% CI: 0.054, 0.644, p = 0.024; and adults: 95% CI: 0.007, 0.368, p = 0.043) (Figure 3C,E and Figure S5B). Here, VEGFA is linked to attention deficit-hyperactivity disorder.