Mabel should be provided with an explanation of addiction, and how it differs from physical dependence. Addiction is a "primary, chronic, neurobiologic disease with genetic, psychosocial, and environmental factors influencing its development and manifestations."52 Characteristics of addiction include inability to control drug use, compulsive use and continued use even when harm or craving occurs. In contrast, physical dependence is "a state of adaptation that is manifested by a drug class specific to withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood level of the drug and/or administration of an antagonist".52 Tolerance involves decreased effectiveness of a drug over time.