Even though it’s an especially sluggish Monday, you might want to reconsider that third cup of coffee, say University of Vermont researchers: The way an individual responds to caffeine might affect their risk of stimulant abuse.

People differ dramatically in how they respond to drugs,” said study author Stacey Sigmon. “For example, a single dose of a drug can produce completely opposite effects in two people, with one absolutely loving and the other hating the drug’s effects. It is important to improve our understanding of these differences, as they may reflect key individual differences in vulnerability or resilience for drug abuse.”

Researchers first divided the participants into whether they were “choosers,” meaning those who chose caffeine over the placebo in the study, or “nonchoosers,” meaning the participants who decided to take the placebo instead caffeine in a majority of choice sessions in the study. “Choosers” made up the majority of the participants during the experiment:

“There were no significant differences regarding pre-study caffeine intake or other characteristics between the two groups. During the second phase of the study, all participants received various doses of d-amphetamine and rated how much they liked or disliked each dose. The researchers found that caffeine choosers reported significantly more positive subjective effects and fewer negative/unpleasant effects of d-amphetamine compared to nonchoosers, particularly at the highest doses. On the other hand, caffeine nonchoosers reporter fewer positive effects and more unpleasant effects of d-amphetamine compared to choosers.”

The researchers said the findings of this study are the first to reveal that “caffeine reinforcement prospectively predicts the positive subjective effects of another drug.”

“While these data do not mean that every coffee lover is at risk for proceeding to cocaine abuse,” Sigmon said, “this study does show that individuals vary markedly in their subjective and behavioral response to psychomotor stimulants, and those for whom a modest caffeine dose serves as a reinforcer are the same folks who subsequently report more positive subjective effects of d-amphetamine. Future research will be important to examine whether caffeine reinforcement predicts vulnerability to reinforcement and abuse of classic psychomotor stimulants such as amphetamine and cocaine.”

Source: University of Vermont

Heather Rudow is a staff writer for Counseling Today. Email her at hrudow@counseling.org.

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