NASHVILLE, Tenn. — Dopamine has been called the “feel-good” hormone and the “pleasure molecule” for years. Its link to the brain’s reward response makes it a particularly key part of treating psychiatric diseases. However, a new study finds everything we know about dopamine may be completely wrong! Researchers from Vanderbilt University say dopamine levels don’t just increase in response to pleasure, but also go up when someone experiences stress.
Study authors say the discovery may lead to a complete re-think of how doctors look at disorders like addiction and even neurological conditions like Parkinson’s disease.
“In the scientific community, research has helped us understand that dopamine’s role in learning and memory is more complex than that, but we did not have a complete and accurate theory that could explain what dopamine actually does in the brain.”
Dopamine ‘not a reward molecule at all’
Researchers say the reward prediction error theory revolves around the idea that dopamine have a connection to the expectation that rewards are coming. The theory points to dopamine tracking every error someone makes as they try to achieve some sort of reward. However, the new study finds this hormone is much more complex.
“While rewards increase dopamine, so do stressful stimuli,” Calipari reports. “We then go on to show that dopamine is not a reward molecule at all. It instead helps encode information about all types of important and relevant events and drive adaptive behavior—regardless of whether it is positive or negative.”
Researchers used cutting-edge technology to study the diverse neurobehavioral processes that take place when the brain releases dopamine. Using machine learning and computational modeling to analyze the data, the team believes their findings should result in a “revision of textbook facts regarding dopamine in the central nervous system.”
“A common theme of all drugs of abuse is that they increase dopamine release in the brain, which helped feed the notion of dopamine as a reward molecule. This work clearly demonstrates a much more sophisticated role for this neurotransmitter, and it means we need to rethink models of addiction that depend on the dopamine/drug reward mentality,” says Danny Winder, director of the Vanderbilt Center for Addiction Research.
Calipari adds that their study is rewriting what scientists know about dopamine, what the “feel-good” hormones encodes in the brain, and how it drives human behavior when the brain releases it.
Important discovery for Parkinson’s patients
Study authors note that people with Parkinson’s disease see their dopamine levels severely disrupted. Those with disorders such as addiction, anxiety, depression, and schizophrenia also experience problems with the production of dopamine.
Looking at these deficits with these new findings in mind may help doctors rework their treatment plans for these conditions.
“We plan to research how this framework fits into our understanding of drug addiction and how drugs alter dopamine signaling to disrupt behavior within this novel framework,” Calipari concludes.
“Most of our understanding of addiction neurobiology centers around dopamine and the dopaminergic network, as many therapeutic approaches that aim to treat addiction target dopamine. However, altering dopamine without having a full understanding of what dopamine actually does may lead to many unforeseen side effects, and more importantly, failed treatment strategies. This new knowledge about what dopamine actually does will affect many fields outside neuroscience and have a strong impact on human lives and health outcomes.”
The findings appear in the journal Current Biology.