GBX2 and attention deficit-hyperactivity disorder: In addition to genes associated with Alzheimer’s disease, which decreases the ability to focus on, recall or organize information, we found methylation of other genes that are usually expressed in the brain (Table S17), such as Bai2 involved in spatial and learning memory [77], Dbx1 involved in innate behaviour [78], Gbx1 and Gbx2 in memory and learning [79,80] or Stxa1 in working memory and attention deficit/hyperactive disorder [81].