Addiction psychiatry is a medical subspecialty within psychiatry that focuses on the evaluation, diagnosis, and treatment of people who are suffering from one or more disorders related to addiction. This may include disorders involving legal and illegal drugs, gambling, sex, food, and other impulse control disorders. Addiction psychiatrists are substance abuse experts. Growing amounts of scientific knowledge, such as the health effects and treatments to substance abuse, have led to advancements in the field of addiction psychiatry. These advancements in understanding the neurobiology of rewarding behavior, along with federal funding, has allowed for ample opportunity for research in the discipline of addiction psychiatry. Addiction psychiatry is an expanding field, and currently there is a high demand for substance abuse experts in both the private and public sector.