“’We don’t know whether decreased dopamine was a preexisting condition or the result of heavy cannabis use,’ said Dr. Abi-Dargham. ‘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’”.
A Columbia University research team recently performed a study to test dopamine release in habitual cannabis users. The study consisted of 11 individuals between the ages of 21 and 40 who had a severe dependence on marijuana. This dependence includes several years of use and that have resulted in a daily dependence on the drug. The research team’s main focus was to take a closer look at the potentially addictive effects of cannabis on key regions of the brain, especially in that of young users. Using a radiolabeled molecule that binds to dopamine receptors in the brain, the researchers were able to track the release of dopamine in key areas of the brain. Compared with the control tests, the cannabis users had a significantly lower dopamine releases. This difference had an effect on the sub regions of the brain that involved associative and sensorimotor learning. The scientists also tested the relationship between dopamine release and cognitive performance on learning and working memory tasks. Lower dopamine release was associated with worse performance on tasks, however, there was no difference between the control and the cannabis using group. This resulted in the conclusion that they were unsure if the decreased dopamine was a preexisting condition or the result of cannabis use, but that long-term, heavy cannabis consumption can impair the dopaminergic system.