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Study shows disconnect in reward processing among cocaine users

Although cocaine users exhibited strong motivation to seek out rewards, their ability to adjust behavior was impaired and they were less fulfilled once achieving rewards, according to recent findings.

“Only about 10% of people who try cocaine go on to become habitual users,” study researcher John J. Foxe, PhD, of University of Rochester Medical Center, New York, said in a press release. “So there is clearly something different going on in the brains of addicts that is causing them to crave and abuse the drug.”

To assess anticipatory and consummatory reward processing in cocaine addiction, researchers recorded high-density event-related potentials while study participants performed a speeded response task that systematically varied anticipated probabilities of reward receipt. Study participants included 23 active cocaine users and 23 age-matched healthy controls.

Cocaine users exhibited increased anticipatory responses to reward predictive cues, but these responses were not as strongly modulated by reward probability as in controls.

Cocaine users exhibited blunted responses to feedback about task success or failure and did not use the information to update reward predictions.

Further, cocaine users exhibited blunted responses to reward feedback.

Anhedonia was associated with reward motivation among cocaine users and controls. Anhedonia was also associated with decreased monitoring and reward feedback responses among cocaine users.

“Despite the fact that they seemed to want it more, the cocaine users enjoyed their reward less and then did not learn from their errors,” Foxe said in the release. “A key question that arises is whether these differences in our addict participants were already present in the brain before these individuals ever used drugs or whether the differences resulted from the drug use. If they predate the addiction, then these measures could potentially be used to identify children at risk for addiction before they ever actually use. We will need to study these measures in high-risk children to figure out if this is a possibility, but it is an exciting prospect that is worthy of further investigation.”

Disclosure: Please see the full study for a list of all authors’ relevant financial disclosures.