A new study from Brazil has shed light on the complex origins of attention-deficit hyperactivity disorder, commonly known as ADHD. Researchers discovered that both a person’s genetic predisposition for ADHD and experiences of childhood maltreatment independently increase the likelihood of experiencing ADHD symptoms in adulthood. Furthermore, the study suggests that genetic factors that raise the risk of ADHD may also indirectly increase the risk of a child experiencing maltreatment.