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NIDA News Release Contact: Beverly Jackson
Michelle Muth
FOR RELEASE, June 26, 2000

Cocaine and Alcohol Combined Are More Damaging to Mental Ability Than Either Drug Alone

Scientists have found that cocaine abuse coupled with use of alcohol leads to more impulsive decision-making and to poorer performance on tests of learning and memory than does use of either cocaine or alcohol alone. The negative effects on the ability to think clearly persist for at least a month after the substance use stops, according to an article about the study in the June 27 issue of Neurology.

"This study reveals important basic information about the way these substances interact," says NIDA Director Dr. Alan I. Leshner. "It also has significant implications for drug abuse treatment, which involves learning and remembering concepts that help recovering drug abusers to change behaviors and avoid situations where they might use drugs."

Dr. Jean Lud Cadet, of NIDA's Intramural Research Program in Baltimore, and Dr. Karen Bolla, of Johns Hopkins Medical Institutions in Baltimore, studied the interactive effects of cocaine and alcohol in 56 adult cocaine abusers. Roughly half the study participants also consumed at least 10 alcoholic drinks per week. All participants abstained from both cocaine and alcohol during the four-week study.

During the first three days of the study the participants were given a battery of tests to measure general intelligence, verbal memory and learning, and attention, planning, and mental flexibility. The tests were repeated during the fourth week of the study.

"The results of this study support the view that cocaine abuse can have a major negative impact on the brain and these effects are compounded by the concurrent use of alcohol," explained Dr. Cadet.

The National Institute on Drug Abuse is a component of the National Institutes of Health, U.S. Department of Health and Human Services. NIDA supports more than 85 percent of the world's research on the health aspects of drug abuse and addiction. The Institute carries out a large variety of programs to ensure the rapid dissemination of research information and its implementation in policy and practice. Fact sheets on the health effects of drugs of abuse and other topics can be ordered free of charge in English and Spanish by calling NIDA Infofax at 1-888-NIH-NIDA (644-6432) or 1-888-TTY-NIDA (889-6432) for the deaf. These fact sheets and further information on NIDA research and other activities can be found on the Home page at

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