Neural circuit selective for fast but not slow dopamine increases in drug reward.
Level 2 - randomized trial
Individual experimental crossover trial in humans with a registered trial protocol (NCT03326245).
PubMed 37938560 · doi:10.1038/s41467-023-41972-6
What was done
Twenty adults received methylphenidate orally (slow brain delivery) and intravenously (fast brain delivery) while undergoing simultaneous PET-fMRI in a registered trial (NCT03326245). The authors estimated the speed of striatal dopamine increases, assessed associated brain activity and connectivity (primary endpoint), and tested temporal associations with self-reported high ratings (secondary endpoint).
What was found
The abstract reports no numerical values, effect sizes, or confidence intervals. It reports that fast, but not slow, dopamine increases activated a corticostriatal circuit comprising the dorsal anterior cingulate cortex, insula, and their connections with the dorsal caudate, and that this activation paralleled self-reported high ratings.
Why it matters
The findings demonstrate in humans that the rate of dopamine elevation, not just total level, determines specific salience-network engagement and subjective reward, explaining why faster brain delivery increases drug abuse liability.
Limits
The sample size was small (n = 20), reducing statistical precision. The abstract does not report participant demographics, substance use history, blinding details, or exact quantitative effect sizes.
Cited by
- supports The speed of drug administration determines the magnitude of the dopamine peak and how far dopamine drops below baseline, making smoked crack cocaine more reinforcing than snorted or oral cocaine.