Neurotransmitters are like chemical messengers between the different parts of the brain. Studies indicate that ADHD causes problems with the chemical messengers that connect two brain areas: the prefrontal cortex and the basal ganglia. These areas communicate through two neurotransmitters called dopamine and noradrenaline. It is believed that in people with ADHD, there is an alteration in the way noradrenaline and dopamine level are regulated, leading to reduction in their levels and abnormal functioning.