P.sycho pharmacology

Psychopharmacology 47, 165-168 (1976)

9 by Springer-Verlag 1976

Effects of Caffeine Consumption on Nicotine Consumption LYNN T. KOZLOWSKI* Department of Psychology, Columbia University, New York, New York, U.S.A.

Abstract. Coffee-drinking cigarette smokers take in more nicotine when they ingest almost no caffeine than when they ingest an amount of caffeine ranging from 75 mg to 300 rag. They do not take in relatively less nicotine as the dose of caffeine increases from 75 nag to 300 rag. It seems, then, that something due to caffeine deficit is responsible for the effect. Heavier users of caffeine show this effect less strongly than do lighter users of caffeine. These results are discussed in terms of the discriminability of caffeine and nicotine deficits and the possible influence of differential tolerance to caffeine. The importance of evaluating caffeine consumption when studying nicotine use and the importance of considering the chronic level of use of these drugs when studying their effects on behavior is indicated. Key words: Cigarettes - Nicotine - Coffee Caffeine - Drug dependence - Tolerance - Drug interaction - Dose-response.

The interaction of caffeine and nicotine use has been largely ignored as an object of study, but it is interesting for several reasons. The concurrent use of nicotine and caffeine is common: cigarette smokers are more likely to be coffee drinkers than are non-smokers (Schubert, 1965; Thomas, 1973). Caffeine and nicotine have significant, predominantly stimulatory, physiological and behavioral effects in doses achieved in cigarette smoking and coffee drinking (Goldstein et al., 1969; Jarvik, 1970; Levi, 1967; Ritchie, 1970); and have been considered dependence-producing drugs (Brecher, 1972; Russell, 1971). * Presently at Department of Psychology, Wesleyan University, Middletown, Connecticut, U.S.A. 06457. This paper is based on a Dissertation submitted to Columbia University.

Smokers appear to regulate nicotine intake (Frith, 1971; Herman, 1974; Jarvik et al., 1970; Lucchesi et al., 1967); varying nicotine content of a cigarette or of a nicotine preload causes compensatory variation in puffing or other nicotine intake parameters (Ashton and Watson, 1970; Kozlowski et al., 1975). Experts concerned with smoking cessation have advised that coffee should be given up along with cigarettes (American Heart Association, 1969). This advice is given only in consideration of the habitual connection between coffee and cigarettes. No consideration is given to physiological and pharmacological connections between the two activities. Both drugs stimulate the adrenergic system; see Stripling and Alpern (1974). A pilot study indicated that decreases in caffeine consumption produced increases in nicotine consumption. The present study was designed to establish this effect and explore the mechanisms behind it. Comparison of the effects of caffeine manipulations on smoking in light and heavy coffee drinkers was undertaken to evaluate the importance of chronic levels of caffeine use for caffeine's effect on smoking.

METHOD Caffeine. O, 75, 150, and 300 mg of caffeine were added to separate glass vials containing I teaspoon of decaffeinated coffee (FreezeDried Sanka Brand 97 % Caffein Free Coffee| 3 mg caffeine per cup of coffee). Lactose was added to the 0 mg of caffeine to hide the variations in white powdered caffeine dose (cf. Goldstein et al., 1969). Subjects. The subjects were secretaries or junior executives of a corporation in New York City. Potential subjects with long latencies to their first cigarette in the morning (e.g., 3 h) were avoided: it was felt that such people could not be very 'addicted' to nicotine, to go without the drug for such a period. Table 1 shows how the light ( < 3 cups/day) and heavy (> 3 cups/day) caffeine users differed as cigarette smokers. It was difficult to find light coffee users who were suitably heavy smokers. (Half of the subjects were

Psychopharmacology 47 (1976)

166 Table 1. Self-reported nicotine use Caffeine

N

Age

Number of years Average daily cigarette consumption smoked at least 20 cig./day

Time in min to 1st cig. in morning

use

Heavy

Mean (S.D.)

16

33.5 (7.57)

36.25 (9.60)

7.94 (3.73)

30.81 (34.83)

Light

Mean (S.D.)

8

29.38 (5.12)

27.25 (9.44)

6,38 (5.52)

83.13 (53.32)

1.33 0.20

2.08 0.05

0.78 0.44

2.76 0.01

df t = P =

(22)

male, half female-balanced across chronic caffeine use: no sex differences were found.)

~ ~

Procedure. Subjects were told that the experiment concerned the relationship between coffee and cigarette use and that their coffee intake would be controlled for the first 31/2 h after the time of their usual first cup of coffee. Instead of their usual coffee, they drank only the provided cup of coffee during this 31/2-h period. No other beverages were allowed. The experiment lasted 4 days per subject: one session on each of the four drug levels. Order of presentation of caffeine levels was balanced. Subjects filled out a set of 4-point unipolar symptom scales (alert, energetic, bored, relaxed, sleepy, headache, and upset stomach) at the first cup of coffee and at the end of the experimental session. These scales were included to assess the relationship between symptoms and the effects on smoking. Subjects also rated on a bipolar 5-point scale how "Good-Bad" the coffee was and on a 4-point unipolar scale the perceived strength of the coffee.

LIGHTCAFFEINE USERS( n = 8 ) HEAVY CAFFEINE USERS( n = 16 )

6

Z

E 03

z

a, 5

\

O

(.9 uJ Z

Vo z

4

Nicotine. A free pack of the subject's own brand was delivered each morning. They were to be opened when the first cup of coffee was finished. To measure cigarette intake, the number of cigarettes left in the pack at the end of the 3~/2-h period was counted by the experimenter. A foil pouch was provided for the collection of cigarette butts. The 312-h duration of the experiment was chosen to maximize the changes of getting at least 5 spent filters from each subject per session (the number needed for chemical analysis of nicotine content), while not allowing the period to exceed the average plasma half-life of caffeine (Axelrod and Reichenthal, 1953). The nicotine analyses of the spent filters were performed as in Charles et al. (1969). The measure of nicotine consumption occasionally required adjustment. Now and then a filter was charred or lost and, therefore, unusable for the nicotine analysis. Residual nicotine in a 5 or more filter sample was determined. This figure was divided by the number of cigarettes in the usable sample. The mg of nicotine per filter was then adjusted by the filter efficiency of the brand smoked, to estimate how much nicotine per filter was reaching the subject's mouth (as in Ashton and Watson, 1970). This figure was multiplied by the total number of cigarettes smoked (charred and uncharred) to get the best estimate of the total amount of nicotine delivered to the mouth of the smoker-the Nicotine Consumption. The relationship between Nicotine Consumptio n and the measured nicotine in the spent filters was assumed to be linear. RESULTS

Nicotine Consumption. F i g u r e 1 s h o w s t h e m e a n s f o r N i c o t i n e C o n s u m p t i o n , T h e o n l y s t a t i s t i c a l l y significant f i n d i n g is t h e m a i n effect o f caffeine levels

'

0

I

75

I

150

!

300

CAFFEINE mg Fig. 1. Nicotine consumption (mg nicotine delivered to mouth) of light and heavy caffeine users as a function of caffeine dose

[ F ( 3 , 6 6 ) = 3.20, P < 0.03]. T h e c o m p a r i s o n s bet w e e n t h e L i g h t - H e a v y c a f f e i n e u s e r d a t a w e r e all n o n - s i g n i f i c a n t (Fs < 1). T h e r e is n o i n t e r a c t i o n bet w e e n caffeine d o s e s a n d c h r o n i c caffeine use [ F (3,66) = 1.15, P = 0.33]. C o f f e e - d r i n k i n g c i g a r e t t e s m o k e r s t a k e in m o r e n i c o t i n e w h e n t h e y ingest a l m o s t n o c a f f e i n e t h a n 9w h e n t h e y i n g e s t a n a m o u n t o f caffeine r a n g i n g f r o m 75 m g t o 300 m g (Ps < 0.05, b y c o m p a r i s o n F - t e s t s ) ; t h e y d o n o t t a k e in r e l a t i v e l y less n i c o t i n e as t h e d o s e o f c a f f e i n e i n c r e a s e s f r o m 75 m g t o 300 m g . It w o u l d seem, t h e n , t h a t s o m e t h i n g d u e to caffeine deficit is r e s p o n s i b l e f o r t h e effect. T o r e p e a t , t h e r e w a s m o r e s m o k i n g o n 0 m g caffeine, b u t n o d o s e - r e s p o n s e effect. The data for number-of-cigarettes-smoked was a n a l y z e d in t h e s a m e w a y as t h e N i c o t i n e C o n s u m p -

L. T. Kozlowski: Effectsof CaffeineConsumption on Nicotine Consumption

167

tion measure: it showed an almost identical pattern of results with comparable levels of statistical significance.

Table 2. Correlations of change in nicotine consumption (0 ragmean of the 3 caffeinelevels)with self-reportof chronic coffeeand cigarette use

Symptom and Coffee Ratings. Neither item by item

Change AveragedailyAveragedaily in nicotine consumption consumption consumption coffee cigarettes

analysis of the symptom ratings nor indices of 'withdrawal' or over stimulation produced significant differences between Light and Heavy caffeine users or according to the manipulations of caffeine intake (Ps > 0.25). The ratings of 'goodness' and 'strength' of the coffee did not show significant differences (Ps > 0.25) : subjects did not discriminate the caffeine manipulations.

Correlations. To use more information from this parametric data than provided by the ANOVA breakdown of light and heavy caffeine users, the four Nicotine Consumption measures per subject were transformed to a single measure of Change in Nicotine Consumption. The intake on the 0-mg day was subtracted by the mean intake on the three caffeine days. Larger positive scores reflected greater smoking on placebo than on caffeine days. Table 2 shows the correlations of change in Nicotine Consumption with self-reports of average daily coffee and cigarette consumption. As chronic coffee consumption increases, the size of the caffeine effect on smoking decreases: chronically heavier users of caffeine show the caffeine effect on smoking less strongly than do chronically lighter users of caffeine. Three of the four heaviest coffee drinkers actually smoked less on the placebo day than on the caffeine days. This strengthens the negative correlation, but the correlation does not depend on this fact. Chronic nicotine use, though related to chronic coffee consumption, was not directly related to the use of nicotine in the experiment.

DISCUSSION Why would heavier caffeine users be less influenced by caffeine deficits than lighter caffeine users ?

Explanation L Assume that as experience with caffeine increases, the discriminability of caffeine deficit and nicotine deficit becomes greater. Deficit of either drug triggers a signal which 'tells' the body to light up a cigarette or have a cup of coffee. The user becomes more adept at discriminating nicotine deficit from caffeine deficit as the drug use is more established (perhaps as separate drug dependency systems develop). This would explain why the heavier caffeine users were less responsive to the caffeine manipulations. If this explanation is correct, using higher caffeine doses in this study should not disclose a dose-response effect o f caffeine on smoking,

Change in nicotine consumption 1.00 Average daily consumption coffee Average daily consumptioncigarettes

0.55**

0.01

1.00

0.54"* 1.00

** P < 0.0I.

Explanation II. Heavy caffeine users are more tolerant to caffeine than are light users (Colton et al., 1968). The effective difference between 0 mg and the caffeine doses would be less for caffeine-tolerant than for nontolerant users. Whatever function is satisfied by the presence of caffeine, it was less satisfied in the heavy users, given the same caffeine doses as the light users. For those who normally drank 3 or 4 cups of coffee during the experimental time period, the 300 mg caffeine dose was hardly a maintenance dose of caffeine. This would suggest that if the heavier users were given more caffeine, a stronger effect on smoking would be seen in them. The usual advice to give up coffee drinking while trying to stop smoking is probably in need of reconsideration: the habitual connections need to be weighed against the pharmacological and physiological connections between coffee and cigarettes. It is clearly important to evaluate chronic caffeine use when studying the effects of caffeine (cf. Goldstein et al., 1969). This is likely to be true for the study of any drug that is used at different chronic l e v e l s especially if drug dependence is involved. Also, the present research indicates that, when studying nicotine use in humans, caffeine use should be at least measured, if not controlled. Acknowledgements. Henry R. Randolph, Philip Morris Research Center, Richmond, Virginia, performed the nicotine analysis. Thanks go to Stanley Schachter, William L. Dunn, Jr., Kathleen MacHan-Kozlowski, Greg Kuhlman, Alfred B. Udow, and to Philip Morris, Inc.

REFERENCES American Heart Association: How to stop smoking. (Pamphlet), 1969 Ashton, H., Watson, D. W. : Puffingfrequencyand nicotine intake in cigarette smokers. Brit_ reed. J. 1970II, 679--681

168 Axelrod, J., Reichenthal, J. : The fate of caffeine in man and a method for its estimation in biological material. J. Pharmacol. exp. Ther. 107, 519-523 (1953) Brecher, E. M. : Licit and illicit drugs. Boston: Little, Brown, 1972 Charles, J. L., Stahr, H. M., Ikeda, R. M. : Automated determination of nicotine in total particulate matter of cigarette smoke. Tobacco Sci. 13, 5 4 - 5 8 (1969) Colton, T., Gosselin, R. E., Smith, R. P. : The tolerance of coffee drinkers to caffeine. Clin. Pharmacol. Ther. 9, 31 - 39 (1968) Frith, C. D. : The effect of varying the nicotine content of the cigarettes on human smoking behavior. Psychopharmacologia (Berl.) 19, 188-192 (1971) Goldstein, A., Kaiser, S., Whitby, O.: Psychotropic effects of caffeine in man. IV. Quantitative and qualitative differences associated with habituation to coffee. Clin. Pharmacol. Ther. 10, 489 (1969) Herman, C. P. : External and internal cues as determinants of the smoking behavior of light and heavy smokers. J. Personal. Soc. Psychol. 30, 6 6 4 - 672 (1974) Jarvik, M. E. : The role of nicotine in the smoking habit. In: Learning~nechanisms in smoking. W. A. Hunt, ed., Chicago: Aldine 1970 Jarvik, M. E., Glick, S. D., Nakamura, R. K. : Inhibition of cigarette smoking by orally administered nicotine. Clin. Pharmacol. Ther. 11, 5 7 4 - 576 (1970) Kozlowski, L. T., Jarvik, M. E., Gritz, E. R. : Nicotine regulation and cigarette smoking. Clin. Pharmacol. Ther. 17, 9 3 - 97 (1975)

Psychopharmacology 47 (1976) Levi, L. : The effect of coffee on the function of the sympathoadreno-mednllary system in man. Acta med. scand. 181, 4 3 1 438 (1967) Lucchesi, B. R., Schuster, C. R., Emley, G. S. : The role of nicotine as a determinant of cigarette smoking frequency in man with observations of certain cardiovascular effects associated with the tobacco alkaloid. Clin. Pharmacol. Ther. 8, 7 8 9 - 796 (1967) Ritchie, J. M. : The xanthines. In: The pharmacological basis of therapeutics. L.S. Goodman and A. Gilman, eds., (4th ed.). New York: MacMillan 1970 Russell, M. A. H.: Cigarette smoking: a natural history of a dependence disorder. Brit. J. med. Psychol. 44, 9 (1971) Schubert, D. S. P. : Arousal seeking as a central factor in tobacco smoking among college students. Int. J. Soc. Psychiat. 11, 221 (1965) Stripling, J. S., Alpern, H. P. : Nicotine and caffeine: disruption of the long-term store of memory and proactive facilitation of learning in mice. Psychopharmacologia (Berl.) 38, 187-200 (1974) Thomas, C. B. : The relationship of smoking and habits of nervous tension. In: Smoking behavior: motives and incentives. W. Dunn, ed. Washington: V. H. Winston & Sons, 1973

Received August 21, 1975; Final Version December 5, 1975

Effects of caffeine consumption on nicotine consumption.

Coffee-drinking cigarette smokers take in more nicotine when they ingest almost no caffeine than when they ingest an amount of caffeine ranging from 7...
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