At birth, we identified nine CpGs that predicted later ADHD symptoms (p < 1 × 10–7), including ERC2 and CREB5. Peripheral blood DNA methylation at one of these CpGs (cg01271805 in the promoter region of ERC2, which regulates neurotransmitter release) was previously associated with brain methylation. Here, CREB5 is linked to attention deficit-hyperactivity disorder.