When a pattern of substance abuse results not just in a craving for the substance but also in an actual physiological need for the substance, the person is said to have an addiction. Substance abuse simply refers to a pattern of use that causes serious social, legal, or interpersonal problems for the user.
Clearly, what is deﬁned as substance abuse is therefore at least somewhat dependent on cultural change. In the late nineteenth century, for example, cocaine was widely available in nonprescription medications in the United States, including toothache drops for children. Conversely, alcoholic beverages were illegal in this country for nearly a decade in the twentieth century.
Not all substance abuse results in addiction, of course. When an addiction is present, a pattern of physiological dependence (characterized by both tolerance and withdrawal) develops, along with, usually, a pattern of psychological dependence (a pattern of compulsive use, along with a feeling of being unable to function without the substance). Tolerance means that the effective dose of the substance increases over time—there is a physiological need for larger and larger doses of the substance to achieve the same effect, or a signiﬁcantly reduced effect from continued use of the same amount. The amount of tolerance that develops varies wildly from substance to substance and from individual to individual. Abusers of opioids and stimulants, for example, may develop levels of tolerance that would kill a nonuser. Heavy smokers may consume a number of cigarettes daily that would have made them very ill when they ﬁrst started.
Where there is tolerance, withdrawal usually follows. Withdrawal is a set of physiological, behavioral, and cognitive changes that results when a person who has been using a substance heavily goes without it for long enough that blood or tissue concentrations of the substance decline signiﬁcantly. Withdrawal symptoms associated with different drugs vary substantially but can include becoming very ill, to the point of the user’s life being in jeopardy, as with alcohol and some opiates. Alcohol withdrawal can cause a syndrome known as delirium tremens, or the DTs, which includes serious illness and hallucinations. The substance-dependent person’s logical response to this is to recognize that the illness is caused by the absence of the substance, and so the solution is clear: get some more. In some cases of substance dependence, the individual’s entire life comes to revolve around getting the substance, using it, recovering from its use, and going to ﬁnd more.
The most widely abused categories of drugs are opioids (or opiates), stimulants, and depressants. Contrary to popular belief, there is no evidence of either marijuana or psychedelic drugs producing a physiological dependence, though psychological dependence certainly develops in many users, especially marijuana users.
Although the popular image of drug abuse involves such illegal substances as heroin and cocaine, abuse of prescription drugs is on the rise in the United States, and now constitutes a major public health problem. According to the National Institute on Drug Abuse (NIDA), in 1999 about 2 percent of the population aged 12 and over (4 million people) were using the following prescription drugs nonmedically: 2.6 million were using painkillers (opioids), 1.3 million were using sedatives and tranquilizers, and .9 million were using stimulants.
- National Institute on Drug Addiction. NIDA Research Report— Prescription Drugs: Abuse and Addiction. NIH Publication No. 01-4881, 2004.