In an article appearing in the May 5 issue of the Journal of the American Medical Association (JAMA), addiction researchers at the National Institutes of Health compared marijuana use in the U.S. adult population in 1991 - 92 and 2001 - 02. They found that the number of people reporting use of the drug remained substantially the same in both time periods, but the prevalence of marijuana abuse or dependence increased markedly. This new study showed that increases in the prevalence of abuse or dependence were most notable among young African-American men and women and young Hispanic men.
This is the first study to assess long-term trends in marijuana abuse and dependence in the United States using the most up-to-date classification system - the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV).
The researchers from the National Institute on Drug Abuse (NIDA) and the National Institute on Alcohol Abuse and Alcoholism (NIAAA) compared trends in marijuana use, abuse, and dependence using the DSM-IV categories. The DSM defines marijuana abuse as repeated instances of use under hazardous conditions; repeated, clinically meaningful impairment in social/occupational/educational functioning; or legal problems related to marijuana use. Marijuana dependence is defined as increased tolerance, compulsive use, impaired control, and continued use despite physical and psychological problems caused or exacerbated by use.
"Marijuana is the most commonly used illegal substance in the United States, and its use is associated with educational underachievement, reduced workplace productivity, motor vehicle accidents, and increased risk of use of other substances," says NIDA Director Dr. Nora D. Volkow. "This study suggests that we need to develop ways to monitor the continued rise in marijuana abuse and dependence and strengthen existing prevention and intervention efforts, particularly developing and implementing new programs that specifically target African-American and Hispanic young adults."
Dr. Wilson Compton, Director of the Division of Epidemiology, Services and Prevention Research at NIDA, Dr. Bridget Grant at NIAAA, and their colleagues evaluated data from two large, national epidemiologic surveys conducted 10 years apart - the National Longitudinal Alcohol Epidemiologic Survey (NLAES) and the National Epidemiological Survey on Alcohol and Related Conditions (NESARC).
A total of 42,862 men and women ages 18 years and older participated in the 1991 - 1992 NLAES study, which was conducted by the NIAAA under the leadership of Dr. Grant. She was also the principal architect for the 2001 - 2002 NESARC study, which included 43,093 similarly aged men and women. Both surveys included the same core questions to assess marijuana use, abuse, and dependence.