Studies suggest that ADHD is hereditary. This means the condition is more common among those who have a close relative with ADHD. Research continues to focus on the brain’s chemical messengers dopamine and norepinephrine, which play a role in such behaviors as attention and movement. Besides genetics, scientists are considering possible environmental factors, as well as how brain injuries, nutrition and social arenas might contribute to the impact of ADHD. Again, there is more definite knowledge within the study of ADHD over other neurological conditions.