use despite knowledge of a persistent physical or psychological problem likely to have been caused by use of the substance.
Addiction, as defined by Dorland's Medical Dictionary, would fall within the dependence diagnosis, but would be somewhat more severe. It requires, in addition to regular heavy use, four symptoms. One of these is dependence (physical or psychological); the others are a tendency to increase dosage (which is equivalent to tolerance in the dependence diagnosis), an overwhelming desire or need (compulsion) to continue use and to obtain the drug by any means (which appears in the DSM-IV definition of dependence as use in larger amounts than intended and inability to stop use, even when the drug's detrimental effects are known), and a detrimental effect on the individual and society (which appears in the DSM-IV definition of dependence as giving up social, recreational, and occupational activities to use the drug).
In addition to these efforts to definition the states experienced by individuals (e.g., tolerance, dependence, addiction) there are also various descriptions of a continuum regarding the use or consumption of drugs, legal and illicit. These descriptions include (1) "occasional use to regular use" (CDC, 1987), (2) "use, abuse, dependence, and recovery" (Gerstein and Harwood, 1990), and (3) "general use versus problematic use" (Reuter, 1993). For the purposes of this chapter, we will adopt a similar approach to analyzing the data. Specifically, we will discuss the continuum of those who ever used opiates, those who ever become dependent on opiates, those who become addicted, and those addicts who have been treated.
The data, drawn from multiple sources, show a steady reduction in numbers along this continuum. The vast majority of Americans have never used a self-administered, nonprescribed opiate. Of those who have used one, about half do not proceed beyond occasional use. Others progress to a relatively brief period of dependence (Biernackie, 1986) and cease use without treatment.
At the other end of the continuum, however, are those who engage in substantial use over long periods, become dependent, and fail at voluntarily ending their dependence. These are the addicts for whom methadone treatment is intended, treatment that has given rise to the methadone regulations. Although they represent a relatively small percentage of the total users of opiates, addicts constitute a large absolute number who contribute disportionately to drug-related crime and threats to the public health. Much more is known about the heroin addict group than about those who use heroin occasionally or are briefly dependent on it, because it is the addicts who generally come to the attention of treatment and criminal justice personnel.