People who are dependent on caffeine tend to score higher on tests of impulsiveness and sensation-seeking than nondependent adults.

The same is true of people who use more dangerous drugs than caffeine.

However, unlike other drug users, the caffeine-dependent do not score high on tests of risk-taking, according to a study published in the August issue of APA's Experimental and Clinical Psychopharmacology (Vol. 13, No. 3).

In addition to highlighting who may be vulnerable to caffeine addiction, the study shows that many adults struggle with a drug some consider to be harmless, says study author Heather Jones, a fifth-year clinical psychology student at the University of Maryland.

A full 60 percent of college students in her initial survey had tried and failed to quit caffeine, says Jones, who hopes future studies might replicate her finding in a noncollege population. Most of the students got their caffeine fix from coffee, she notes.

"Although the effects of caffeine withdrawal varied across participants, I had some people coming in for the study who were having serious, withdrawal-related migraine headaches that were stopping them from getting their work done," says Jones. "Caffeine dependence may lead to significant impairment in some people."

To identify who might be vulnerable to such problems, Jones and her co-authors randomly selected 30 caffeine-dependent and 30 nondependent students from a pool of 701 students who completed a screening survey.

The caffeine-dependent students were drawn from the top 10 percent of caffeine consumers in the sample--drinking on average 423.4 milligrams of caffeine a day, or about four cups of coffee.

Both groups completed the Eysenck Impulsiveness Scale--which asks participants to answer questions such as "Do you often do things without planning?"

The students also completed the Zuckerman Sensation Seeking Scale, noting how much they enjoy activities such as mountain climbing.

Finally, the participants took a computer-based assessment of risk-tolerance, in which they pumped a simulated balloon as full of air as possible without letting it burst.

Both groups scored similarly on the test of risk-taking, however, the caffeine-dependent group tended to score significantly higher on the sensation-seeking and impulsivity tests.

While the correlation does not show that sensation-seeking leads to increased caffeine consumption, the finding sets the stage for future research that could eventually help those developing caffeine-dependence prevention programs target vulnerable populations, says Jones.


American Psychological Association Monitor Volume 36, No. 8 September 2005