Human Coffee Drinking: Manipulation of Concentration and Caffeine Dose

Abstract

In a residential research ward coffee drinking was studied in 9 volunteer human subjects with histories of heavy coffee drinking. A series of five experiments was undertaken to characterize adlibitum coffee consumption and to investigate the effects of manipulating coffee concentration, caffeine dose per cup, and caffeine preloads prior to coffee drinking. Manipulations were double-blind and scheduled in randomized sequences across days. When cups of coffee were freely available, coffee drinking tended to be rather regularly spaced during the day with intercup intervals becoming progressively longer throughout the day; experimental manipulations showed that this lengthening of intercup intervals was not due to accumulating caffeine levels. Number of cups of coffee consumed was an inverted U-shaped function of both coffee concentration and caffeine dose per cup; however, coffee-concentration and dose-per-cup manipulations did not produce similar effects on other measures of coffee drinking (intercup interval, time to drink a cup, within-day distribution of cups). Caffeine preload produced dose-related decreases in number of cups consumed. As a whole, these experiments provide some limited evidence for both the suppressive and the reinforcing effects of caffeine on coffee consumption. Examination of total daily coffee and caffeine intake across experiments, however, provides no evidence for precise regulation (i.e., titration) of coffee or caffeine intake.

Reinforcing Effects of Caffeine in Coffee and Capsules

“…The caffeine dose in the caffeinated condition was in the mid-range of caffeine doses that normally occur in cups of brewed coffee (Bunker & McWilliams, 1979;Gilbert, Marshman, Schwieder, & Berg, 1976). Previous research showed that, in general, subjects could not differentiate reliably, on the basis of taste or appearance, between decaffeinated coffee plus lactose and decaffeinated coffee plus caffeine (100 or 150 mg/cup) (Goldstein, 1964;Griffiths, Bigelow, Liebson, O'Keeffe, et al, 1986).…”

“…The first unequivocal demonstration of the reinforcing effects of caffeine in humans was provided in a discrete-trial choice study that was done as part of a series of experiments to investigate the self-administration and reinforcing effects of caffeine in residential volunteers with histories of heavy caffeine use as well as histories of drug and/or alcohol abuse Griffiths, Bigelow, Liebson, O'Keeffe, et al 1986). imenter-scheduled exposures to color-coded caffeinated or decaffeinated beverage coffee under double-blind conditions; subsequently, subjects were given a choice between the two coffees.…”

“…In addition to discrete-trial choice procedures, concurrent-schedule choice procedures and progressive-ratio schedules have been used for differentiating the relative reinforcing effects of drugs (Griffiths, Brady, & Bradford, 1979;McLeod & Griffiths, 1983;Pickens, Cunningham, Heston, Eckhert, & Gustafson, 1977). The present studies used variations on these procedures to extend systematically the series of residential ward studies investigating the self-administration of caffeine in subjects with histories of heavy caffeine use Griffiths, Bigelow, Liebson, O'Keeffe, et al, 1986). More specifically, Experiment 1 used a variation on a concurrent-schedule choice procedure to elaborate knowledge about the reinforcing effects of caffeine by examining preference between capsules containing either caffeine or placebo.…”

Neuropsychological Effects of Caffeine: Is Caffeine Addictive?

“…When self-administration is limited to once a day, when doses of 100 and 200 mg are reinforcing, while doses of 400 mg and greater tend to be avoided [137]. Recent research shows that caffeine reinforcement occurs in 100% of heavy caffeine consumers that also had histories of drug abuse [138,139]. For moderate caffeine users, caffeine reinforcement occurs in about 45% to 80-100% of the experimental subjects [135,[140][141][142].…”

Efeito da cafeína no comportamento e na longevidade de operárias de abelhas africanizadas Apis mellifera L. (Hymenoptera: Apidae)

“…Estudos psicofarmacológicos têm demonstrado que a dependência física da cafeína pode ocorrer com seu uso persistente (GRIFFITHIS et al, 1986(GRIFFITHIS et al, , 1990 Sakagami (1953).…”