Addiction, like cancer, is a strong word for a serious medical disorder. The experience of addiction is one of extreme drives that are resisted and recurrent episodes of despair as these drives overcome the best intentions of the patient. Stopping addictive behaviour leads to a period of withdrawal with at the least marked dysphoria and at the worst death. Almost everyone uses alcohol, tobacco or other drugs at some life stage, yet only a minority become addicted, proving specific individual vulnerabilities. These include significant genetic variables such as liver enzyme polymorphisms and brain processes such as dopamine and GABA dysfunction.