Yeah and Adderall, a drug prescribed for ADHD, also has abnormal effects on the bodies dopamine system.
The studies cite adolescent users as the ones getting the side effects, and that the later they use the less pronounced they are. Where is the study that says similar significant decreases in dopamine production occur in adults? The people who would be legally allowed to smoke it. I'm not trying to undermine your argument, I'm just looking for a better perspective. Finding reliable studies about marijuanna is like trying to find a slightly darker needle in a needle stack. Counting the one you posted, I've seen 3.