When examining inattention, we found an interaction between MAOA genotype and children’s trauma experiences, with MAOA-L associated with increased inattention at low and moderate levels of trauma exposure, and MAOA-H was associated with increased inattention at extreme levels of trauma. Approximately 20% of the cohort met criteria for ADHD, with comparable numbers of children in the low, moderate, severe, and extreme trauma groups meeting criteria for this diagnosis. Studies looking at main effects of MAOA genotype in conferring risk for ADHD have been mixed. Some studies found an association between MAOA-L and ADHD symptoms (35,36), whereas others found the opposite (37,38); to the best of our knowledge, no study except the investigation by Kim-Cohen (12) reported a G×E effect with MAOA-L conferring vulnerability for inattention in maltreated children.
