A recent research study provided evidence of dopamine release reduction in the brain for individuals who engaged in heavy marijuana use. Until now studies have shown that other drugs including cocaine and opioid drugs like heroin reduced the release of dopamine in the striatum of the brain but the evidence did not cover heavy marijuana use. Columbia University Medical Center professor of psychiatry Anissa Abi-Dargham, MD, was the lead author of the paper and explained the reasoning behind the study, stating “In light of the more widespread acceptance and use of marijuana, especially by young people, we believe it is important to look more closely at the potentially addictive effects of cannabis on key regions of the brain.” Dr. Abi-Dargham received funding for the study from National Institute on Drug Abuse grant R01 DA022455-01A1. The Netherlands Organisation for Scientific Research also provided a Rubicon grant to Dr. van de Giessen to help fund the study.
The study evidence suggests that heavy marijuana use can cause dopamine release reduction in the brain but further studies are needed. According to Dr. Abi-Dargham “We don’t know whether decreased dopamine was a preexisting condition or the result of heavy cannabis use. But the bottom line is that long-term, heavy cannabis use may impair the dopaminergic system, which could have a variety of negative effects on learning and behavior.” American Psychiatric Association past president and CUMC Chair of Psychiatry Dr.Jeffrey Lieberman, MD, remarked that “these findings add to the growing body of research demonstrating the potentially adverse effects of cannabis, particularly in youth, at the same time that government policies and laws are increasing access and use.”