The wickedly addictive nature of cocaine is thought to affect long-term decision making processes more than previously believed, says a Texas A&M University researcher who has just been given a unique $1.4 million grant to study the problem.
Barry Setlow, a professor in the Behavioral and Cellular Neuroscience Program in the Department of Psychology, has received a five-year grant from the National Institutes of Health to examine the relationship of cocaine and its effects on choices. What is learned from the laboratory rats exposed to cocaine could change the way health care experts look at treatment methods for humans who are battling addiction to the drug.
“The project is aimed at determining how chronic cocaine administration affects a type of decision making called ‘impulsive choice,’” Setlow explains.
“In a nutshell, we – and that includes rats or humans – prefer large rewards over small rewards. But if we have to start waiting for the large rewards, then the small – and instant – rewards quickly become more attractive. The longer the delay to the large reward, the more attractive the small reward becomes.”
In Setlow’s experiments, the rats will actually become addicts by choice. They will press a small lever to get a “hit” of cocaine, and Setlow will examine various aspects of decision making by the rats and what long-term mechanisms affect behavior.
“Does the rat have to be a full-blown addict, or will just a small amount of cocaine do the trick for it to respond differently? That’s a big question we want to find out,” he says.
“We will give the rats a choice to make – a small immediate reward, such as a small amount of food, or a larger but delayed reward, like a large amount of food. We will look to see how our cocaine-addicted rats choose compared to rats who have not used cocaine, what brain changes are responsible for these altered choices, and ultimately, whether these changes can be reversed.
“Importantly, all of the cocaine use in our rats will happen months before we start testing their decision-making abilities, so the rats are not on cocaine while they are choosing. We’re interested in how that earlier period of cocaine use causes long-term – perhaps permanent – changes in the brain that lead to impulsive decision making.”
Information learned from the project could lead to improved treatment for a variety of addictions, currently a huge public health problem. Studies show that about 22 million Americans (about 9 percent of the population over 12 years of age) abuse or are addicted to alcohol or illegal drugs. Because increased impulsive choices appear to persist long after a drug user has stopped taking drugs, there are high relapse rates that follow even the best currently used addiction therapies, Setlow adds.
“What we learn could give us some better answers to these and other big questions, and hopefully help in the treatment of millions of people who suffer from substance addiction,” he says.