A new study of how cocaine affects the brain may help explain why people who use the drug make many destructive decisions, according to the Los Angeles Times.
Chronic cocaine use changes brain circuits that help people learn from mistakes, the researchers said. They measured electrical activity in the region of the brain associated with managing errors in reward prediction. When things go better than expected, nerve cells release and absorb more of the chemical dopamine. When events fail to meet expectations, nerve cells in that area of the brain release less of the chemical. When outcomes match predictions, nerve cells release a steady amount of dopamine, the article explains.
The study included 75 people, including some who don't use cocaine, some who chronically use cocaine but tested negative for cocaine use in the past 72 hours, and some who chronically use cocaine and tested positive for recent use.
All the participants played a computer gambling game in which they had to predict whether or not they would win or lose money on each turn. Participants who were chronic cocaine users showed no significant difference between expected and unexpected losses, while people who did not use cocaine had a greater feedback signal for unexpected outcomes.
"This study shows that individuals with substance use disorder have difficulty computing the difference between expected versus unexpected outcomes, which is critical for learning and future decision making," study lead researcher, Muhammad Parvaz of the Icahn School of Medicine at Mount Sinai in New York said in a news release. "This impairment might underlie disadvantageous decision making in these individuals."
The study appears in the Journal of Neuroscience.
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