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mise à jour
15 septembre 2002
Physiology & Behavior
1998; 63; 1; 35-39
 Caffeine withdrawal symptoms following
brief caffeine deprivation
BG. Phillips-Bute, JD. Lane
Department of psychiatry and behaviral sciences; Duke University,
Meducal Center, Durham, USA

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CAFFEINE is one of the most popular drugs in the world today, but its habitual use is not without side effects. One of them is the clear pattern of physiological withdrawal symptoms that appears when habitual consumers abruptly stop their intake. The best known symptom following, sudden caffeine abstinence is headache, which was described as early as 1952. Studies in the late 1960s reported that abnormal sleepiness and irritability were also common symptoms. Withdrawal symptoms are not associated only with high levels of chronic caffeine intake. It was noted that withdrawal symptoms of headache, fatigue, sleepiness and decreased vigor, alertness and activity can occur even in people who normally consume as little as 100 mg, of caffeine per day. More severe symptoms have been reported as well. For example, a study of light to moderale coffee drinkers reported increased scores for clinical symptoms of depression and anxiety and the presence of flu-like symptoms, in many individuals, after 2 days od caffeine abstinence.These symtoms of caffeine withdrawal can clearly be clinically signifian, and the may be quite common given the widespread consumption of the drug.
Most experimental investigations of caffeine withdrawal symptoms have involved several days or more of caffeine deprivation. While extended periods of deprivation provide the opportunity to observe the full range and intensity of clinical symptoms, extended deprivation is relatively rare in everyday life. Much more common are shorter periods of deprivation, for example when someone misses his or her regular morning coffee. Even such brief periods of caffeine deprivation can lead to clinically signifiant symptorns of headache and fatigue.
 
A recent study in our laboratory investigated mood, symptoms and psychomotor performance in coffee drinkers who had drunk coffee ad libitum or been abstinent during the morning prior to testing at midday, an experimental design intended to simulate these natural episodes of brief deprivation. After only a few hours of caffeine deprivation, participants reported decreased energy, desire to socialize and ability to concentrate as well as increased drowsiness, lethargy and yawning. Participants reported that they did not feel like working, and headache and flu-like feelings were reported by some. In contrast, we detected no decrements in performance of a variety of computerized psychomotor tasks.
 
The emphasis on natural conditions of caffeinated beverage consumption in this study raised two concerns about the interpretation of results. First, participants differed in their actual caffeine intake during the morning of ad lib consumption, which could have made detection of mood, symptoms and performance effects more difficult by increasing the variability of changes associated with acute deprivation. Second, participants were aware of their experimental condition on each day of testing. Their expectations could have biased reports of mood and symptoms, perhaps exaggerating the differences between the ad lib and deprived conditions.
 
The present study was designed to continue the investigation of the effects of short-term caffeine deprivation on mood, symptoms and psychomotor performance under more controlled conditions that would address the limitations of the first study. The ad lib coffee consumption and deprivation conditions were replaced by double-blind administration of a fixed dose of caffeine (250 mg) and placebo. Controlled doses eliminated the variability in caffeine intake associated with ad lib consumption. Double-blind administration provided a control for participants expectations and their influence on symptoms and motivation for task performance. These changes shifted the focus from the naturalistic study of coffee drinking behavior and isolated the contributions of the drug caffeine to the pattern of mood, symptom and performance effects observed after short-term deprivation. [...]
 
DISCUSSION :
 
The results of this study confirm that some withdrawal symptoms will appear in regular coffee drinkers after only a few hours of caffeine deprivation beyond normal overnight abstinence. The pattern of affective and sornatic symptoms sleepiness, yawning, fatigue, decreased vigor are consistent with previous studies, including our own. The results of the present study demonstrate that the effects can be attributed to caffeine and do not require the presence and absence of the many sensory and behavioral cues associated with coffee drinking. Moreover, the doubleblind counterbalanced administration of drug and placebo treatments ensures that the effects cannot be attributed to expectation, experimental demand or other systematic bias.
 
The failure to detect performance degradation in the caffeine deprivation condition contradicts the anecdotal reports of participants, but is consistent with our earlier study. The research literature suggests that caffeine has inconsistent effects on cognitive performance, especially when administered to habitual consumers. Our experience suggests that task length may be a critical variable in studies of caffeine deprivation. Participants appeared to be able to push themselves for the 2 Min of task performance required, and they may have been able to overcome any deficits associated with deprivation. Longer tasks may be necessary to demonstrate the effects of caffeine deprivation on performance. A recent study found dramatic performance differences during simulated managerial tasks conducted for 8-h intervals. The authors attributed the success of their demonstration to the complexity of the tasks involved, but it is also possible that the extreme length of the task revealed deficits that could not be overcome by the temporary efforts of caffeine deprived participants. Future studies may be able to characterize the nature of the psychomotor deficits that participants report in their subjective experience of caffeine deprivation.
 
This study found that acute caffeine deprivation was associated with lower casual blood pressure, confirming the results of an earlier study. The difference of 5 mm Hg may be important to understanding the relationship between caffeine consumption and blood pressure in the population. Epidemiological studies have not consistently found elevated blood pressures in coffée drinkers, as would be expected given the experimental evidence of the pressor effects of caffeine. However, many of the epidemiological studies utilized blood pressure measurements taken under conditions of acute caffeine deprivation, which we showed in this study are associated with a depressor response in habitual consumers. The normal blood pressures of coffee drinkers would be underestimated when caffeine abstinence was required, and the relationship between coffée drinking and elevated blood pressure may have been obscured in those studies. Further consideration of the effects of caffeine consumption on blood pressure in the population is warranted given the popularity of the drug and the importance of blood pressure as a risk factor for cardiovascular disease, but studies must take normal patterns of caffeine consumption into account and avoid artifacts related to acute caffeine deprivation.
 
The present study has two limitations that may merit discussion. First, there was no objective confirmation of compliance with the caffeine treatment condition. Participants did report following instructions for taking the caffeine and placebo capsules according to schedule, but caffeine concentrations in plasma or saliva were not measured. Some participants may have failed to comply with instructions for abstinence from caffeinated beverages prior to testing. However, random noncompliance would not likely yield the observed pattern of significant differences in mood and symptoms, nor would it yield the lack of différences in performance scores, which were caused more by the consistency in the means across conditions than by large variability in the participants' scores. Thus, the lack of objective measures of caffeine concentration is probably not a important limitation of the present study. Second, the estimated daily caffeine intake of our sample of habitual coffee drinkers was higher than might be expected. Mean caffeine intake for our group was 603 mg/day, or 7.8 mg/kg of body weight, but recent estimates suggest that caffeine-consuming adults average only 4 mg/kg/day. This difference raises the question of whether our results might apply only to the heavier than average consumer, but we do not think so. Our sample included participants with a wide range of daily caffeine intakes, and multiple regression analyses failed te, detect any relationship between self-reported intake and the magnitude of the changes associated with caffeine deprivation. Apparently, cïffei'ne deprivation had similar effects on moderate and heavy consumers alike in our study, which should at least partially resolve the issue of generalizability to a broader range of caffeine consumption.
 
Evidence of the measurable symptoms of withdrawal associated with short-term caffeine deprivation adds to our understanding of the health consequences associated with habitual consumption of caffeine in coffee, tea and other products. To the extent that this research paradigm mirrors normal patterns of consumption, the results of this study demonstrate the kind of effects that brief deprivation can have. Because habitual coffee drinkers probably do miss their morning coffée occasionally, the associated pattern of sleepiness and fatigue is a clear potential side effect of daily consumption. Such mild symptoms may be merely an annoyance for most people, but the increase in sleepiness and fatigue could be critical in occupations requiring sustained attention and alertness, such as truck-driving and controlling air traffic among others. Moreover, the aversive symptoms of withdrawal following brief deprivation may motivate continued daily morning coffee drinking, a relationship that would indicate the presence of physical dependence and raise questions about caffeine as a potential drug of abuse. Given the expanding popularity of coffee and other caffeinated beverages in this country, the harmful consequences of these side effects merit further consideration.
 
-Evans SM, Griffiths RR. Caffeine withdrawal: a parametric analysis of caffeine dosing conditions. J Pharmacol Exp Ther. 1999;289(1):285-294.
-Phillips-Bute BG, Lane JD.Caffeine withdrawal symptoms following brief caffeine deprivation. Physiol Behav 199763(1):35-39
-Lane JD Effects of brief caffeinated-beverage deprivation on mood, symptoms, and psychomotor performance. Pharmacol Biochem Behav. 1997;58(1):203-208
-Lane JD, Phillips-Bute BG Caffeine deprivation affects vigilance performance and mood. Physiol Behav.1998;65(1):171-175