Caffeine reinforcement: the role of withdrawal |
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Authors: | K J Schuh R R Griffiths |
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Institution: | (1) Behavioral Pharmacology Research Unit, Department of Psychiatry and Behavioral Science, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA Fax (+1) 410/550-0030, TP |
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Abstract: | This study examined caffeine’s acute and withdrawal effects in moderate caffeine consumers (mean = 379 mg/day caffeine) to
compare the relative contributions each might have to caffeine reinforcement. Subjects were caffeine restricted on the night
before each of three sessions, which generally occurred at weekly intervals; these restrictions lasted until the session was
completed approximately 19 h later. During the first two sessions, subjects received either placebo or caffeine (each subject’s
average daily intake). These two conditions occurred using a double-blind, quasi-random, crossover design. At the end of each
session subjects completed the POMS, a caffeine withdrawal questionnaire, and a Multiple-Choice Form on which subjects made
a series of discrete choices between receiving the drug again or receiving varying amounts of money. This form also included
negative money amounts to assess how much subjects would forfeit to avoid placebo (e.g., withdrawal symptoms after placebo).
During the third session, one of the previous choices was randomly selected and the consequence of that choice was implemented.
Placebo increased self-reported feelings of “worn out,”“headache,” and “flu-like feelings,” and decreased “alert,”“upset stomach,”“helpful,”
and “well-being” relative to caffeine. On the Multiple-Choice Forms, subjects chose to receive caffeine rather than an average
of $0.38 and to forfeit $2.51 to avoid receiving placebo again. “Headache” was significantly correlated with amount of money
forfeited to avoid placebo. These results suggest that, under these conditions, choice of caffeine is more potently controlled
by avoiding withdrawal than it is by the positive effects of caffeine.
Received: 21 December 1995 / Final version: 26 October 1996 |
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Keywords: | Caffeine Withdrawal Reinforcement Physical dependence Subjective effects Multiple-Choice Procedure Humans |
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