Cocaine Addicts Can Be Highly Sensitive to Reward

New research has found that people who are addicted to cocaine are particularly prone to developing habits that lead to behavior that is resistant to change, regardless of potentially devastating consequences.

“Addiction does not happen overnight, but develops from behavior that has been repeated over and over again until individuals lose control,” said Dr. Karen Ersche from the Department of Psychiatry at the University of Cambridge, who led the research.

In the study, published in the journal Science, Ersche and her colleagues tested 125 participants, including 72 addicted to cocaine and 53 who had no history of drug addiction, on their inclination to develop habits.

They found that people addicted to cocaine were much more likely than the healthy participants to make responses in an automatic fashion, but only if they had previously been rewarded for responding in the same way.

The addicted individuals simply continued repeating the same responses they had previously learned, regardless of whether their actions made sense or not, the researchers said.

In a different context, however, where participants had to perform an action to avoid electrical shocks, the addicts did not develop habits, according to the researchers. In fact, they were much less inclined than the healthy participants to make an effort to avoid the electric shock in the first place.

In the first experiment, participants were asked to learn the relationship between pictures, and a correct response was rewarded with points. After a long training period, participants were informed that some pictures were no longer worth any points.

The cocaine addicts were less likely to assimilate the information about the change in reward, and were also more likely to continue responding in an automatic way, regardless of whether they were rewarded or not, according to the researchers.

In the second experiment, the same participants were shown two different pictures on a screen, which they learned to associate with receiving an electric shock. Participants were then taught a strategy on how they could avoid the shocks by pressing a foot pedal.

The cocaine addicts were less adept at avoiding the electric shocks in the first place, possibly due to learning and/or motivational impairment, and subsequently did not develop avoidance habits, the researchers noted.

“Our experiments highlight the particular difficulties faced when it comes to changing behavior in people with cocaine addiction: They are highly responsive if their behavior is rewarded — for example a ‘high’ from drug use — but then quickly switch to autopilot, becoming unable to change that behavior in light of different consequences,” said Ersche.

“By contrast, when cocaine users are facing adversity, they are less inclined than healthy people to do something about it.”

The findings have “significant implications” for the treatment of people with cocaine addiction, she noted.

“Clearly punitive approaches are ineffective, as the prospect of something bad happening to them won’t make cocaine users more likely to change their behavior,” she said. “Interventions that build on their particular strength in developing habits, by training the implementation of more desirable habits to replace drug-taking habits, are likely to be more effective.

“Our findings also suggest that cocaine users would need to be actively protected from — rather than simply warned about — adverse consequences, because they will likely fail to avoid them if left to their own devices.”

There is no medical treatment for cocaine addiction, Ersche said, noting most individuals are treated with talk or cognitive therapy.

The results show that a different approach to treating cocaine addiction might be of enhanced benefit to cocaine users, she said.

The researchers are now working to better understand the brain systems underlying cocaine users’ proneness to habits and their lack of avoidance, and to use this knowledge to develop more effective treatments for cocaine addiction.

Source: University of Cambridge