Data from a major US study (the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions, NESARC) indicate there is substantial comorbidity between substance use disorders and independent mood and anxiety disorders, according to the report in the August issue of the Archives of General Psychiatry.
About 20 percent of persons with a current (at the time of the survey or within the past year) substance use disorder have a mood or anxiety disorder within the same time period. Similarly, about 20 percent of persons with a current mood or anxiety disorder also have a current substance use disorder.

Based on DSM-IV criteria, an estimated 17.6 million American adults (8.5 percent)
meet diagnostic criteria for an alcohol use disorder and approximately 4.2 million (2 percent) meet criteria for a drug use disorder. Overall, about 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.

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
non-institutionalized 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.

Data 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 authors concluded that high rates of comorbidity among persons who sought treatment for mood, anxiety, or substance use disorders suggest that primary care physicians, mental health specialists, and alcohol and drug abuse specialists should assess patients for multiple mental health disorders.

"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."