Dopamine is one of the brain’s neurotransmitters—a chemical that ferries information between neurons. Dopamine helps regulate movement, attention, learning, and emotional responses. It also enables us not only to see rewards but to take action to move toward them. Since dopamine contributes to feelings of pleasures and satisfaction as part of the reward system, the neurotransmitter also plays a part in addiction. Dopamine is heavily involved in the motor system. When the brain fails to produce enough dopamine, it can result in Parkinson’s disease. The primary treatment for Parkinson’s disease, therefore, is a drug called L-dopa, which spurs the production of dopamine. Dopamine has also been implicated in schizophrenia and ADHD, and the brain systems underlying these conditions as well as substance abuse disorder are complex. The activity of the dopamine system depends on the state of one’s dopamine receptors, for instance—and in people with these conditions, the chemical interacts with other factors in ways that have yet to be explained. People with low dopamine may also be more prone to addiction. The presence of a certain kind of dopamine receptor is associated with sensation-seeking, more commonly known as risk-taking.