DSM-IV provides separate categories for Substance Abuse and Substance Dependence. The typical substance abuser is someone who gets into recurrent, but intermittent, trouble as a consequence of recreational binges. This is in contrast to the continuous and compulsive pattern of use that is typical of DSM-IV Substance Dependence.
At the extremes, the difference between abuse and dependence are clear cut. The abuser goes through periods when he seems able to take it or leave it, using the substance in a controlled way or abstaining from it altogether. Then comes the bender with a bad outcome. Another peaceful period, then another destructive bender, and so on. The person doesn't learn from the repeated painful experiences that a couple of drinks (or snorts or pills or joints) can lead to a binge, and a binge can, and often does, have serious (and sometimes even catastrophic) consequences.
Substance Abuse also must be distinguished from run of the mill recreational bingeing, which is unfortunate but usually does not qualify as a mental disorder. The definition of Substance Abuse requires that there be "a maladaptive pattern of substance use manifested by significant adverse consequences" in at least one of four different domains of trouble: 1) driving under the influence; 2) other legal problems (e.g., disorderly conduct, assault, etc.); 3) reduced performance at work or school; and 4) problems with interpersonal relations and family life.
Substance Abuse can be the first step on a path that eventually leads to Substance Dependence. The threshold between the two is crossed when the periodic bingeing turns into continuous use and the motivation switches from pleasurable recreation to needing the substance on a regular basis just to get by. Substance Dependence requires some combination of 1) tolerance, 2) withdrawal, and 3) a pattern of compulsive use. Tolerance means you have diminishing pleasurable returns -- you need to take more and more of the substance to get the same buzz or any buzz at all. Withdrawal means that trying to reduce or stop the substance leads to unpleasant (and sometimes dangerous) symptoms that will drive you to start using again. Compulsive use means you feel driven to do whatever it takes to get the substance despite the fact that it no longer provides much, if any, pleasure.
The DSM-5 draft suggests two radical changes: 1) eliminating the separate categories of Substance Abuse and Substance Dependence and replacing them with one unified category, Substance Use Disorder, and 2) labeling the overall section "The Addiction and Related Disorders." The combined result would be that someone now diagnosed as having DSM-IV Substance Abuse would, in DSM-5, instead be diagnosed as Substance Use Disorder and (given the title of the overall section) would be considered to have an addictive disorder.
The DSM-5 rationale for consolidating what in DSM-IV are the separate categories of Substance Abuse and Substance Dependence comes from factor analytic and latent class analyses that suggest that there is no sharp boundary between them (although the results and their interpretation are far from definitive). The work group is impressed by analyses suggesting that abuse and dependence are unidimensional and lack a point of separation clearly demarcating a boundary between them.
This is a weak rationale and reflects a basic misunderstanding about the nature of all mental disorders: that none of them enjoys a clear boundary with near neighbors. All the DSM disorders overlap with one another and, frequently, also with normality. For example, there is no clear boundary between bipolar and unipolar mood disorder, between anxiety and depression, even between schizophrenic and psychotic mood disorders, and so on, throughout all the sections.
There is thus no matter of principle at stake here. If substance abuse and dependence are to be joined, it must be because there is a clear practical benefit of doing so that outweighs the risks. The work group suggests no pressing practical problem that needs fixing with the DSM-IV definition Substance Abuse. I can see no benefit in its elimination, but there are three substantial risks:
First, what is now Substance Abuse in DSM-IV would be subsumed in a section labeled "Addiction Disorder" in DSM-5. I think it is unwise and unfair to pin the pejorative and stigmatizing label "addict" on someone whose substance problems are intermittent, may be temporary, and are often very influenced by contextual and developmental factors. Take the example of a college kid in a hard-drinking fraternity who binges on weekends and gets into one fight and has one DUI. He is obviously already in serious trouble (and flirting with much worse). His situation certainly does require rigorous and immediate intervention. But what is gained by the stigmatizing label addiction that may jeopardize future insurance, marital and job prospects, and legal status? Most substance abusers are in a passing phase and never become "addicted" in any meaningful sense of that word.
The term "addiction" has never (in its entire history of loose usage) been used in so loose and indiscriminate a fashion. If there is some compelling reason to include it at all in DSM-5 (a question to be addressed in another piece), "addiction" should replace only the term "substance dependence." Allowing the term "addiction" to also cover "substance abuse" seems unnecessary, misleading and potentially harmful.
Second, combining Substance Abuse and Dependence would result in the loss of much valuable distinguishing information, which would all melt into the amalgam. There is a world of difference in behavior, treatment needs and prognosis separating abuse and dependence. The label "substance dependence" clues the clinician that abstinence may trigger severe physiological or psychological withdrawal reactions requiring a special intensity of medical and rehabilitation response. Intervention with abusers, on the other hand, will be more directed to the harmful consequences of the binges, how to avoid binges, and the substitution of other, less dangerous recreational activities. There is also a considerable difference in prognosis: While some with an early history of substance abuse later go on to dependence, most do not and are much more likely to have an early and permanent remission.
Third, the message to the abuser that he is "addicted" to the substance can cut both ways. It might benefit some who would heed this dire warning and take the opportunity to go abstinent. But many others may seize on the many unfortunate connotations associated with being "addicted," including 1) that the substance has already gained a central (and difficult to end) role in the persons life; 2) that it will be terribly difficult to give up the substance because of psychological and/or physical dependence and painful withdrawal symptoms; 3) that all this is somehow biological, fated in the genes, and outside his control or ability to change; and 4) that the individual has reduced personal responsibility for substance use and its consequences. Being "addicted" can become a self-fulfilling prophecy and a great excuse for not meeting responsibilities to self, family, school, and the legal system.
This leads me to suggest two recommendations: 1) retain the useful distinction between Substance Abuse and Substance Dependence; and 2) if the term "addiction" is to be used at all in DSM-5, it should be restricted to substance dependence.