The issue of drug addiction is of great importance to many young adults. It is important to be well informed in order to be able to recognize possible risks and signs in good time. In this section you will learn everything you need to know about the definition of drug addiction and what factors are associated with it. Drug addiction, also known as drug addiction or substance use disorder, is a complex condition that alters a person's brain and behavior. It occurs when someone uses drugs repeatedly and compulsively, even though the effects are negative and he or she has difficulty quitting. To understand drug addiction, it is important to take a closer look at the definition. According to the World Health Organization (WHO), someone is considered a drug addict if he or she meets at least three of the following criteria within a year: