Cocaine: Brain Reward Circuitry Altered, even in Former Users

MedicalResearch.com Interview with:
Krishna Patel, M.S.
Clinical Data Analyst
Hartford Hospital|Institute of Living
Olin Neuropsychiatry Research Center
Hartford, CT-06106

MedicalResearch.com: What are the main findings of the study?

Answer:  We looked at brain response to a monetary incentive delay (MID) task in current and former cocaine users compared to healthy controls using functional MRI. The task measures aspects of sensitivity to rewards and punishments. Current cocaine users showed abnormal under-activation in reward circuitry compared to healthy controls. In some of those regions former cocaine users (who had an average of 4years of abstinence from cocaine) also showed abnormalities. These former users also showed over-activation in the ventral tegmental area of the midbrain, (an important region containing dopamine cell bodies) compared to both healthy controls and current cocaine users. Current and former cocaine users also scored higher on specific impulsivity measures, compared to healthy controls.

MedicalResearch.com: Were any of the findings unexpected?

Answer: We had hypothesized that, former users would show activation patterns intermediate between those of healthy subjects and current cocaine users. During the feedback stage of the MID task former users showed unexpected regional over-activation compared to current users and healthy controls in an important region of the reward network.

MedicalResearch.com: What should clinicians and patients take away from your report?

Answer: Cocaine dependence alters brain reward circuitry regions. Long term abstinence from cocaine may reverse some of the deficits due to drug, but not all. Also, impulsivity is likely a pre-existing factor in addiction.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Dr. Patel: Prediction studies would be useful. Cocaine users could be followed up in rehabilitation treatment centers to further investigate what proportion of them are able to remain abstinent from cocaine over the long haul, and if they have different baseline brain biology and impulsivity profiles compared to the subjects that who relapse to drug use. Also, former cocaine abusers could also be followed up over the longer term to see if the brain alterations we found ever recover fully.

Citation:

Robust Changes in Reward Circuitry During Reward Loss in Current and Former Cocaine Users During Performance of a Monetary Incentive Delay Task

Patel KT, Stevens MC, Meda SA, Muska C, Thomas AD, Potenza MN, Pearlson GD.

Olin Neuropsychiatry Research Center, Institute of Living at Hartford Hospital, Hartford, Connecticut.

Biol Psychiatry. 2013 Oct 1;74(7):529-37. doi: 10.1016/j.biopsych.2013.04.029.
Epub 2013 Jun 15.