A monopolization of the attentional system by drug-related stimuli. For example, if cocaine addicts see white powder, they will probably experience cravings, because their brain associates white powder with cocaine.
Drug addiction is a condition where a person takes a drug compulsively, despite potential harm to themselves, or their desire to stop. Although being addicted implies dependence, it is possible to be dependent on a drug without being addicted. People who take drugs to treat diseases and disorders, which interfere with their ability to function, may experience improvement of their condition.