Hard Habits to Break
by ERIC FOSTER
Statistics show as many as 75 percent of people who try cocaine will become addicted to it. Only one in four is able to quit without help.
Turns out the expression “some habits are hard to break” is true in a very real sense. And the reasons are biological.
Neuroscientist Kevin Ball ’01, associate professor of psychology, is conducting research that may provide clues on how to help people kick a drug or overeating habit. Funded by a three-year, $263,271 grant from the National Institutes of Health, he is using an animal model to study the effects of chronic stress on addicts’ relapse to cocaine seeking and dieters’ relapse to unhealthy eating habits.
“After addicts complete cocaine rehab, the majority go back to using the drug within a few months to a year. A similar thing happens with dieting,” says Ball. “Addiction to drugs, like cocaine, heroin or amphetamines, is so difficult to beat because they cause very big changes to brain structure and chemistry.”
While drug addiction and maladaptive food seeking are not the same, “there is a lot of overlap in the brain systems that drive both behaviors,” says Ball. “Food seeking doesn’t entail the same profound change to the brain. Partly it’s evolutionary; it’s in our DNA. When food was scarce, it was advantageous to seek out calorie-dense foods. In advanced economies, food isn’t scarce anymore.”
The chemistry of addiction
When we do something pleasurable — such as eating our favorite foods or having sex — or are exposed to stimuli that predict such things, our nerve cells release the neurotransmitter dopamine, which is picked up by dopamine receptors. After a short time, the dopamine is reabsorbed by the nerve cells to be used again.
Cocaine and similar drugs hijack our body’s dopamine system by blocking the reabsorption of the chemical. The dopamine receptors are stimulated far longer than normal, creating an intense euphoria. The chemistry of the brain is altered and, with repeated exposure, those changes can become more prevalent, setting the stage for addiction.
It appears that many of the physical changes in the brain that underlie adaptive forms of learning and memory also occur after exposure to addictive drugs, Ball explains. Addiction, therefore, is sometimes conceptualized as a maladaptive form of learning that makes addicts vulnerable to relapse for months, years or a lifetime after treatment.
The role of stress
“We know that chronic stress contributes to many diseases … from heart disease to cancer,” says Ball. “I’m studying the role of chronic stress in
relapse because it induces lasting changes in brain regions implicated in addiction and relapse.”
Acute stress can be adaptive, says Ball. It activates your body’s fight-or-flight mechanism, like you would experience if you walked into your office to find a cobra sitting on your chair. But chronic stress is not adaptive when fight-or-flight mechanisms are continually activated.
“Today we are exposed to stresses that constantly activate our fight-or-flight mechanisms. Stress at home. Stress at work. Money worries. Information
overload,” he says.
Stress and cocaine both activate the dopamine system, but through different mechanisms. And it turns out that activation of the dopamine system by stress can reactivate an addictive behavior.
A possible remedy
In his study, Ball is investigating whether a dopamine antagonist — a drug to block dopamine receptors in the body — will reduce the effects of chronic stress on later relapse vulnerability.
The study will be conducted in three stages.
• Self-Administration Phase: Rats will be given the opportunity to self-administer cocaine or highly palatable food pellets.
• Extinction Phase: The cocaine or food pellets will be withdrawn and a source of stress introduced. This stressor can entail being confined to a small open container in a bright space. A portion of the rats will be administered a dopamine antagonist.
• Reinstatement Phase: The rats will have the opportunity to respond to cocaine- or food-associated cues. This response is the means for measuring relapse.
The question that Ball is seeking to answer is whether the dopamine antagonist, given during the chronic stress introduced at the extinction phase, helps to shield the rats from relapsing into the addictive behavior.
And if it does, perhaps the research will one day lead to a way to shield human addicts from relapse. •
A Research Tradition
The behavioral studies that Kevin Ball is conducting are part of a continuing tradition at Bloomsburg University.
A 2001 BU graduate, Ball was mentored by Steven Cohen, who retired in 2009 after 36 years of service.
Cohen, with more than 75 publications and 39 research grants, was the first Bloomsburg University professor to be awarded grants from the National Science Foundation and the National Institutes of Health.
Ball’s latest grant is his second from the National Institutes of Health. A 2011 grant focused on the effects of MDMA (colloquially known as ecstasy) and neurological foundations of addiction. •