Long-Term Marijuana Use Affects Memory and Attention

A new study of marijuana users seeking treatment determined that long-term users performed worse on most of the memory, attention, time judgment, and information processing tests. The study, "Cognitive Functioning of Long Term Cannabis Use," is published in the March 6, 2002, issue of the Journal of the American Medical Association (JAMA).

The data arose as part of a substudy of the adult Marijuana Treatment Project, a cooperative agreement between SAMHSA's Center for Substance Abuse Treatment (CSAT), the University of Connecticut Medical School, the University of Washington, the University of Connecticut Health Center, and The Village South, Inc., in Miami. Consulting organizations included the National Drug and Alcohol Research Centre of the University of New South Wales, Australia; the University of Wollongong, Australia; the Virginia Polytechnic Institute and State University; and Evergreen Treatment Services of Seattle.

"The findings show that there are significant long-term negative effects of marijuana use," said SAMHSA Administrator Charles G. Curie, M.A., A.C.S.W. "Young people need to know that marijuana is not the harmless substance some have made it out to be. We are committed to continue educating our youth on the damaging effects of marijuana use on both their health and their future."

"This study shows that long-term use of marijuana may have consequences for both individuals and their productivity and performance in the workplace," said CSAT Director H. Westley Clark, M.D., J.D., M.P.H. "There is good treatment available for those who are habitual marijuana users, and we urge them to seek appropriate services through the treatment networks in their communities."

Authors of the study include Nadia Solowij, Robert Stephens, Roger Roffman, Thomas Babor, Ronald Kadden, Michael Miller, Kenneth Christiansen, Bonnie McRee, Janice Vendetti, and Jean Donaldson, project officer for CSAT's Marijuana Treatment Project.

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