Etienne Benson '99, a concentrator in psychology and biology, studied the effect of cocaine addiction on information-processing. With support from the Harvard College Research Program (HCRP), he conducted an experiment that he hopes will help to clarify the relationship between craving and cognition. "I've been interested in addiction since I arrived at Harvard," Benson says, "but my interest was really catalyzed in my sophomore year by a seminar on drug policy taught by William Brownsberger, a former Massachusetts assistant district attorney for narcotics. It was a small, intense class that took an interdisciplinary approach to drug policy, combining neuroscience, psychology, sociology, and public policy, among other things.

"We took a field trip to Massachusetts General Hospital so we could hear about ongoing research by [psychiatrist and instructor at the Medical School] Dr. Randy Gollub and others on the effects of cocaine on the brain," Benson continued. "When I found out that Dr. Gollub was looking for a research assistant, I jumped at the opportunity." Benson launched his own study last fall, which he hopes will shed light on the cognitive aspects of the motivational state of craving. His study also tested the hypothesis that cocaine addiction is accompanied by the kinds of cognitive biases that are seen in a number of psychiatric disorders.

"The mixed evidence for the role of drug craving in drug use may be due to an indirect effect of craving on behavior," Benson explained. "The effect may be mediated by changes in the way cocaine addicts perceive and interpret information about the world. For instance, craving might enhance the ability of cocaine addicts to pay attention to cocaine-related cues and decrease their ability to pay attention to anything else thereby increasing the likelihood of drug use."

According to Benson, information-processing biases like the one he cites have been found in a broad range of psychiatric disorders, including panic disorder and depression. However, very few studies have been conducted on information-processing biases in addictive disorders. Limited research suggests that pathological gamblers and cigarette smokers in short-term withdrawal have a selective bias for words related to their addiction. Until Benson's study, the same tendency had not been proved for cocaine addicts, but Benson said his study showed that cocaine addicts have the same bias toward words related to cocaine addiction. The role that cocaine craving, or subjective desire for the drug, plays had not been previously explored.

To uncover information-processing biases in his subjects, Benson employed a paradigm called the "Stroop task." It was introduced by J. Ridley Stroop in 1935, who showed that people are slower at naming the ink color of a printed word when the word conflicts with the color in which it is printed. (For example, the word "blue," when printed in red ink, might cause us to stumble.) It has since been demonstrated that emotionally charged words cause similar delays in color-naming. "The Stroop task is usually taken as an index of 'cognitive interference,' " Benson said, "and as such it's been used in studies of almost every kind of psychopathology. Patients tend to respond more slowly to words that are related to their disorder 'filth' for obsessive-compulsive disorder, for instance than to unrelated words."

Benson used a modified Stroop task to determine whether cocaine-dependent subjects show a slowed response to cocaine-related words. He also measured the levels of anxiety and craving of the subjects and attempted to correlate them with performance on the Stroop task. Benson conducted the Stroop task test on 40 subjects 20 cocaine addicts and 20 control subjects. The addicts did show a slowed response to cocaine-related words, as Benson expected. Benson had also expected that heavier users would show a slower response than other users, but that did not happen.

Benson did find an unexpected result, however. Those who wanted to quit using cocaine responded slower than those who did not want to quit, possibly because they felt more negatively about their cocaine use than others.

Benson presented his findings this spring in a senior thesis and is writing the complete results for publication. His research was supervised by Richard McNally, professor of psychology, and Gollub. "Professor McNally provided crucial input on the design and implementation of the experiment," Benson said, "while Dr. Gollub assisted in the day-to-day planning of the experiment, the human subjects approval process, and the recruitment of cocaine-dependent subjects." The project has reinforced Benson's desire to attend graduate school in psychology this fall. He plans to study cognitive neuroscience in Stanford University's Psychology Department.

This story originally appeared in The Harvard-Radcliffe Undergraduate Research Programs Newsletter.