Dopamine is a transmitter in the brain crucial for movement, thinking, and memory; although, above all, we know it as the “pleasure hormone”. Now, a new study carried out by researchers at Columbia University Medical Center in New York (USA) has revealed that marijuana use could compromise the dopamine system.
Previous studies had found that drugs considered more “forceful” such as heroin and cocaine decrease the release of dopamine; but, until now, this consequence has never been associated with marijuana.
Most drug addictions end up blunting the release of dopamine during the most dependent phase. On this basis, the researchers wanted to find out if marijuana was linked to effects similar to these. For this, they had the participation of 11 adults between 21 and 40 years old, heavy marijuana users (they smoked marijuana daily), and also 12 adults who did not consume any type of substance.
The experts used the positron emission tomography (PET) technique to track a molecule that binds to dopamine receptors in the brain in order to measure the release of this neurotransmitter in the brain’s striatum, as well as in other regions such as the thalamus, midbrain or globe pallidus.
During the week that the experiment lasted, the participants could not consume marijuana, to prevent the images from measuring the effects of this substance. The results showed that, compared to the control group, the striatum of the volunteers who took marijuana had a lower level of dopamine release ; the same happened with the rest of the regions. All of them had lower levels of dopamine, which is associated with inattention and problems in learning and working memory.
“ We do not know if the decrease in dopamine was a pre-existing condition or the result of cannabis use. But the bottom line is that in the long term , cannabis use can compromise the dopamine system, which could have a variety of negative effects on learning and behavior, ”says Anissa Abi-Dargham, leader of the work.
The study has been published in the journal Molecular Psychiatry.
