The definition of addiction is a progressive narrowing of the things that bring you pleasure. This means that over time, individuals become more and more reliant on a specific substance or behavior to experience pleasure. Addiction can also be characterized by a specific time course of the things that bring you pleasure. In the case of vaping, for example, young people's brains are getting wired to expect a rapid and dramatic increase in dopamine, which can only be achieved through vaping. However, with repeated use, the dopamine system becomes impaired, leading to withdrawal symptoms and a decreased ability to experience pleasure from other activities.