Dopamine
It is now well established that dopamine, a brain chemical, plays a crucial role in processing novelty, surprise and reward – all those thrilling and salient factors in everyday life. No wonder that dopamine levels may be aberrant in those who use recreational substances in excess.
Jessica Ahrens, undertaking PhD at McGill’s IPN program, systematically searched MRI and postmortem studies quantifying dopamine in the midbrain region among persons with substance use disorders.
She found ten studies that measure dopaminergic changes by employing neuromelanin signal – representing dopamine synthesis/turnover in the brain. But the research in this area is not sufficient for us to make clinical use of this marker.
Neuromelanin imaging is a promising approach to further study dopamine neurobiology in substance use.
One day, in the same fashion as markers of liver injury indicate the severity of alcohol use disorder, neuromelanin may get used as a ‘criterion marker’ for substance use disorders. A lot of work needs to be done to get there, and Jessica is doing some of this work now!