Different drugs produce different patterns of addiction with emphasis on different components of the addiction cycle. Opioids can be considered classic drugs of addiction because subjects meet most of the criteria classically associated with addiction, including dramatic tolerance and withdrawal. A pattern of intravenous or smoked drug-taking evolves, including intense intoxication, the development of tolerance, escalation in intake, and profound dysphoria, physical discomfort, and somatic withdrawal signs during abstinence. Intense preoccupation with obtaining opioids (craving) develops that often precedes the somatic signs of withdrawal and is linked not only to stimuli associated with obtaining the drug but also to stimuli associated with withdrawal and the aversive motivational state. A pattern develops where the drug must be obtained to avoid the severe dysphoria and discomfort of abstinence. Other drugs of abuse follow a similar pattern but may involve more the binge/intoxication stage (psychostimulants and alcohol) or less binge/intoxication and more withdrawal/negative affect and preoccupation/anticipation stages (nicotine and cannabinoids).
