The prevalence of alcohol and drug disorders in primary care outpatients is between 23% and 37%. The cost to society of these disorders is staggering. Each year in the United States substance use disorders are associated with 100,000 deaths and costs of approximately $100 billion. The high prevalence of these disorders in primary care outpatients suggests that family physicians are confronted with these problems daily. However, these disorders rarely present overtly. Patients in denial about the connection between their substance use and the consequences caused by it frequently minimize the amount of their use and often do not seek assistance for their substance use problem.
The epidemiology of alcohol and drug disorders has been well studied and is most often reported from data of the National Institute of Mental Health Epidemiologic Catchment Area Program (ECA). Lifetime prevalence rates for alcohol disorders from the ECA survey data were 13.5%. For men, the lifetime prevalence was found to be 23.8%, and for women, 4.7%. The National Comorbidity Survey revealed lifetime prevalence of alcohol abuse without dependence to be 12.5% for men and 6.4% for women. For alcohol dependence, the lifetime prevalence was 20.1% in men and 8.2% in women. The ECA data yield an overall prevalence of drug use disorders of 6.2%. As with alcohol use disorders, drug use disorders occur more frequently in men (lifetime prevalence 7.7%) than in women (4.8%). Characteristics known to influence the epidemiology of substance use disorders include gender, age, race, family history, marital status, employment status, and educational status.
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The difference between abuse and dependence is an important one. With substance abuse, patients retain control of their use. This control may be affected by poor judgment and social and environmental factors, and mitigated by the consequences of the patient's use. Patients who become dependent (addicted) no longer have full control of their drug use. The brain has been "hijacked" by a substance that affects the mechanism of control over the use of that substance. This addiction is far more than physical dependence. The need to use the drug becomes as powerful as the drives of thirst and hunger. Evidence that the brains of addicted individuals are different from those of nonaddicted persons is enormous. Many of these abnormalities predate the use of the substance and are thought to be inherited. In genetically predisposed individuals, substances of abuse cause changes in the dopaminergic mesolimbic system that result in a loss of control over substance use. These changes are mediated by several neurotransmitters: dopamine, γ-aminobutyric acid (GABA), glutamate, serotonin, and endorphins. The different classes of substances of abuse act through one ...