ODD is related to a child’s conduct and how they interact with their family, friends, and teachers. ADHD is a neurodevelopmental disorder. These conditions are different, but can occur together. Some seemingly defiant symptoms may be related to impulsivity in ADHD. In fact, it’s believed that about 40 percent of children with a diagnosis of ADHD also have ODD. Though, just like ADHD, not all children diagnosed with ODD have ADHD.