An estimated 17.6 million American adults (8.5 percent) meet standard diagnostic criteria for an alcohol use disorder and approximately 4.2 million (2 percent) meet criteria for a drug use disorder.
Overall, about one-tenth (9.4 percent) of American adults, or 19.4 million persons, meet clinical criteria for a substance use disorder--either an alcohol or drug use disorder or both--according to results from the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) reported in the current Archives of General Psychiatry.
Conducted by the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, the NESARC is a representative survey of the U.S. civilian noninstitutionalized population aged 18 years and older. With more than 43,000 adult Americans participating, the NESARC is the largest study ever conducted of the co-occurrence of psychiatric disorders among U.S. adults.
Results from the NESARC show that 19.2 million adults (9.2 percent) meet diagnostic criteria for independent mood disorders (including major depression, dysthymia, manic disorder, and hypomania) and 23 million (11.08 percent) meet criteria for independent anxiety disorders (including panic disorder, generalized anxiety disorder, and specific and social phobias).
The NESARC is the first national epidemiologic survey to use the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition (DSM-IV) definitions of independent mood and anxiety disorders to examine the comorbidity, or co-occurrence, of mental health disorders. Independent mood and anxiety disorders exclude transient cases of these disorders that result from alcohol and/or drug withdrawal or intoxication, conditions that usually improve rapidly without treatment once substance use ceases. The distinction is important because the diagnosis of current mood and anxiety disorders among active substance abusers is complicated by the fact that many symptoms of intoxication and withdrawal from alcohol and other substances resemble the symptoms of mood and anxiety disorders and thus, the additional psychiatric disorder may be overlooked.
The NESARC results show substantial comorbidity between substance use disorders and independent mood and anxiety disorders is pervasive in the U.S. general population: About 20 percent of persons with a current (at the time of the survey or within the past year) substance use disorder experience a mood or anxiety disorder within the same time period. Similarly, about 20 percent of persons with a current mood or anxiety disorder experience a current substance use disorder.
NESARC results also indicate high rates of comorbidity among persons who sought treatment for mood, anxiety, or substance use disorders. The high rates of comorbidity among treated persons suggest that primary care physicians, mental health specialists, and alcohol and drug abuse specialists should assess patients for multiple mental health disorders, the authors conclude.
"It would be incorrect for health care professionals to assume that the majority of mood and anxiety disorders are due to substance intoxication or withdrawal and will remit when the patients stops drinking," said Ting-Kai Li, M.D., Director, National Institute on Alcohol Abuse and Alcoholism. "These findings suggest that treatment professionals should be prepared to treat or refer patients in stable remission from substance use for comorbid mood and anxiety disorders. Earlier research has demonstrated that, left untreated, such disorders may lead to substance use relapse and other negative outcomes."
"This study does not resolve questions about causal mechanisms that may underlie relationships between DSM-IV substance use and mood and anxiety disorders," according to Bridget Grant, Ph.D., Ph.D., Chief of the Laboratory of Epidemiology and Biometry, Division of Intramural Clinical and Biological Research. "Analyses of data from NESARC's 'second wave' in 2004-2005 will help to form a foundation for future etiologic research."
In a separate paper appearing in the current issue of the Journal of Clinical Psychiatry [Volume 65:948-958], the authors of the NESARC study reported findings on the prevalence of personality disorders in the United States.