A new study has found that a person's response to caffeine could help predict how a person will respond to other stimulant drugs, such as amphetamine and cocaine.
UVM Associate Professor of Psychiatry Stacey Sigmon, Ph.D., and Johns Hopkins University colleague Roland Griffiths, Ph.D., first employed a choice procedure to identify participants as caffeine "Choosers" and "Nonchoosers" for the study.
Choosers were those who chose caffeine over placebo in the majority (>/= 7) of 10 choice session and Nonchoosers chose placebo over caffeine in the majority of choice sessions. 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.
"People differ dramatically in how they respond to drugs," says 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," she added.
The study has been published in the journal Drug and Alcohol Dependence.