Mobile phone users had a higher risk of ADHD than nonmobile phone users (RR 1.16, 95% CI 1.02 to 1.32, I2=51.6%; Figure 4C), and mobile phone use increased the risk of other unspecific chronic disorders, with a pooled risk of 1.20 (95% CI 0.90 to 1.59, I2=0.0%), including damage to the blood–cerebrospinal fluid barrier and elevated levels of serum S100B levels (Figure 4D). Here, S100B is linked to attention deficit-hyperactivity disorder.