Drug Abuse and Dependence, Epidemiology of

Diagnoses of Drug Abuse and Dependence

Objective criteria to diagnose dependence can be found in the Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association, and the International Statistical [Page 285]Classification of Diseases and Related Health Problems, published by the World Health Organization.

Dependence is diagnosed if at least three of the following problems are present: the user is tolerant to the substance (needs to use more to achieve the same effect or the same amount of substance leads to diminishing effect), experiences withdrawal (exhibits withdrawal symptoms or uses the substance to relieve those symptoms), needs to take larger amounts or for a longer time, wants or unsuccessfully tries to control his or her use, spends most of his or her time getting or using the substance or recovering from its use, gives up important activities to use the substance, or continues to use even with the knowledge that he or she has health problems related to substance use. Maladaptive use that does not meet the criteria for dependence is called abuse. Diagnostic criteria for abuse include failing to fulfill obligations at work, school, or home; recurrent use in physically hazardous situations; recurrent legal problems; or continued use despite serious social or interpersonal problems.

Although abuse and dependence are considered as distinct diagnostic entities, there is considerable overlap between these disorders; abuse of drugs usually involves using a large quantity of one or more substances, and regular use often, though not always, leads to dependence. On the other hand, a minority of those who are dependent do not show symptoms of abuse. In addition, it is more difficult to treat the abuse of those people who are highly dependent than those who are not as dependent. Research suggests that drug dependence changes not only the brain chemicals but also the brain structures, and the more dependent a person is, the more difficult it is to reverse the brain into a nondependent stage.

Distribution of Drug Dependence in the Population

Drug dependence is not distributed randomly in the population. Prevalence of dependence is highest among people aged 18 to 54 years, especially among young adults. The extent to which minorities are affected by dependence varies by drugs, region, and age. For example, in the United States, cocaine dependence is more common among whites who are below 30 years of age and among nonwhites who are above 30 years of age. People in geographic areas with economic deprivation and neighborhood disorganization are also more likely to develop dependence than people in more affluent areas. While treatment is available for drug dependence, only about one in five people with dependence gets treated.

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