29 May 2009

Cocaine users have different brains

Cocaine users seem to have less activity in the parts of their brains that monitor behaviours and emotions, a finding that may make them more vulnerable to addiction to the drug.


Cocaine users appear to have less activity in the parts of their brains that monitor behaviours and emotions, a finding that researchers think may make them more vulnerable to addiction to the drug, a new research shows.

Using MRI scans, the researchers saw there were issues in these regions of the brain when cocaine users were given a test in which fast, correct answers - some dealing specifically with drug use - were rewarded with money. The issues persisted even when the addicts did as well as non-cocaine users on these tests.

"Whether these brain differences are an underlying cause or a consequence of addiction, the brain regions involved should be considered targets for new kinds of treatments aimed at improving function and self-regulatory control," said study author Rita Goldstein, a psychologist at the US Department of Energy's Brookhaven National Laboratory.

The study results appear online in the Proceedings of the National Academy of Sciences. In the experiment, a group of active cocaine users and demographically similar but healthy non-users had to push a button that corresponded to a word related to either drug use (e.g., crack, addict) or a neutral term, depending on the scenario. Fast, accurate answers could earn the test subjects up to a maximum of about R750 for the entire experiment.

Brain 'quieter' in cocaine users
Brain imaging showed that the part of the brain that normally becomes active when people monitor their own behaviour was far quieter in the cocaine users, especially during the parts of the test in which no monetary rewards were being offered, and only neutral terms were being used - sections considered the least "interesting", according to the researchers. Participants who used cocaine most often during the previous month showed the least activity in this area of the brain.

During the section of the test of most interest to the cocaine users - in which they could earn money for their answers and the terms being used were drug-related - activity was much lower than their healthy peers in a part of the brain that usually becomes quiet when a person is suppressing emotions.

This, the researchers said, suggests the cocaine users were trying to fight off drug cravings to focus on the succeeding at the test.

"When you really have to suppress a powerful negative emotion, like sadness, anxiety or drug craving, activity in this brain region is supposed to decrease, possibly to tune out the background 'noise' of these emotions so you can focus on the task at hand," said Goldstein, adding that thoughts of past drug use or using more drugs would be the "noise" in this scenario.

She went on to note that the cocaine users reported high levels of "task-induced craving" during this portion of the test.

Treatments to improve and strengthen activity in the behaviour- and emotion-monitoring portions of the brain - both found in the anterior cingulate cortex region - may help addicts regain self-control and decrease impulsive behaviour, the researchers concluded. – (HealthDay News, May 2009)

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