1. reliance on a psychoactive substance for its pleasurable effects. The dependence is signaled by a high rate of drug use, drug craving, and the tendency to relapse after cessation of use. Many believe that stimulation of the brain’s reward system is the driving force behind drug addiction and that tolerance and physical dependence may not be central to the development of dependency-inducing patterns of drug use.

2. reliance on others for emotional support, often characterized as an excessive need for their guidance, reassurance, and validation.