Study Title and Description
Caffeine deprivation state modulates coffee consumption but not attentional bias for caffeine-related stimuli.
Key Questions Addressed
|1||For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on behavior*?|
Primary Publication Information
|Title||Caffeine deprivation state modulates coffee consumption but not attentional bias for caffeine-related stimuli.|
|Author||LD Stafford,MR Yeomans,|
Secondary Publication Information
There are currently no secondary publications defined for this study.
Extraction Form: Behavior - Design Details - INCLUDED Studies
No arms have been defined in this extraction form.
|Question... Follow Up||Answer||Follow-up Answer|
|What outcome is being evaluated in this paper?||Behavior|
|What is the objective of the study (as reported by the authors)?||Here we explored the relationship between caffeine deprivation, attentional bias to caffeine-related stimuli and subsequent caffeine reinforcement measured by consumption of coffee.|
|Provide a general description of the methods as reported by the authors. Information should be extracted based on relevance to the SR (i.e., caffeine related methods)||Experiment 1 Participants Twenty-eight volunteers (24 women and four men) were recruited from students at Sussex University. Ages ranged from 18 to 29 years (mean 21.1, SD 2.6 years). Potential participants were identified according to self-reported caffeine consumption based on answers to the following: ‘On average, how many cups of coffee do you drink in a typical day?’. ‘What type of coffee do you normally drink?’ (options were instant, decaffeinated instant, filter, decaffeinated filter, other). ‘On average, how many cups of tea do you drink in a typical day?’ and ‘On average, how many cans of soft drink do you drink in a typical day ?’. Individual responses were converted to an approximation of daily caffeine intake by multiplying reported intake by average caffeine content in each drink [based on James (1991): filter coffee 125 mg per cup, instant coffee 70 mg per cup, tea 60 mg per cup, cola 30 mg per can]. Only individuals whose habitual caffeine consumption was estimated at between 150 and 650 mg per day were approached. Design Participants were allocated randomly to one of two conditions that differed in whether they were tested in a caffeine-deprived or nondeprived state (Table 1). They attended one session, in which, following consumption of a drink containing 100mg caffeine (nondeprived) or placebo (deprived), they completed the JWT. The experiment therefore adopted a mixed design in which deprivation state was studied between-subjects and word stimuli within-subjects. Mood scales Mood was assessed using a modified version of the Profile of Mood States (POMS) questionnaire (McNair et al., 1971). Rationale for amending the original 72-item POMS questionnaire was based on the premise that a number of factors were not relevant to caffeine research that is, ‘anger’, ‘depression’ and ‘elated’. The modified version was composed of 39 items from the original inventory, with the addition of ‘jittery/nervous/shaky’, ‘headache’, ‘hungry’ and ‘calm’, which were included to measure withdrawal and general effects of caffeine. Participants rated the 43 items on a 5-point scale from ‘not at all’ to ‘extremely’. From these responses, POMS permits five factors to be extracted: ‘anxiety’, ‘fatigue’, ‘vigour’, ‘confusion’ and ‘friendliness’ and the additional factor of ‘arousal’ (anxiety+vigour)–(fatigue+confusion). Drink and drug administration Preweighed quantities of caffeine hydrochloride (Courtin and Warner, Sussex, UK) and a white powder used as a placebo (maltodextrin, Cerostar) were stored in small, coded plastic tubes to ensure double-blind testing. The quantity of caffeine/placebo was 100mg. Drinks (Strawberry- raspberry swirl, London Fruit & Herb Company, St Albans, UK) were prepared by placing the relevant tea bag in a cup, before pouring in 135 g of boiling water and leaving it to stand for 2min. Once the tea bag had been discarded, the contents of the relevant plastic tube were then emptied into the drink, which was then stirred thoroughly. Procedure Participants were advised to refrain from drinking anything other than water from 23.00 h on the evening before the experiment, and to eat only a light breakfast (with only juice or water). They were further told that saliva samples would be taken prior to each session to check compliance. All testing was conducted in experimental rooms in the Human Psychopharmacology Unit at Sussex University. Participants reported to the laboratory at either 11.00 or 11.30 h. They were told prior to the start that the experiment would last approximately 60 min, and would consist of them consuming a drink, completing some mood forms and a short computer task. On arrival at the laboratory, participants completed the consent form and provided a saliva sample (not analysed). They were then taken to an experimental cubicle and completed the mood questionnaire. Following this, they were presented with the fruit tea and asked to consume all of the drink. The experimenter returned to the cubicle after 5 min to ensure all of the drink had been consumed. The participant was then escorted to the waiting room and was free to read quietly. Forty-five minutes after drink ingestion, participants completed the computer task, followed by a second copy of the mood questionnaire. This was followed by a structured debriefing in which participants were asked to report what they felt the purpose was, and whether or not they had received caffeine. They were finally paid a small amount for their participation. Data analysis Data for two participants were excluded from analysis following responses in debriefing, one of whom admitted consuming a caffeinated beverage prior to testing and the second who had altered caffeine consumption so that it was now outside the study range. The ratings from the modified POMS questionnaire and additional mood items were analysed by subtracting the predrink ratings from the postdrink ratings. These changes in mood between the deprived and nondeprived groups were then analysed using independent t-tests. Experiment 2 Participants Twenty volunteers (nine men and eleven women) were recruited from students at Sussex University using the same procedure as in experiment 1, with the exception of an additional inclusion criterion that potential participants had to self-report habitual consumption of at least one cup of coffee a day. Participants averaged 22.4±0.6 years, weighed 69.2±1.9 kg and self-reported consuming an average of 305±34mg of caffeine daily. Design A within-subjects design was used to examine the effects of the caffeine deprivation state (deprived vs. nondeprived) on attentional bias for caffeine-related stimuli Drink and drug administration The quantity of caffeine/placebo was 150mg, with drug preparation and storage being identical to experiment 1. As cold drinks were used in this experiment, however, drink administration was different. Drinks were prepared by placing the contents of the relevant tube in a plastic beaker containing a small quantity of the drink (Sainsbury’s pure orange juice). This was then placed in a microwave for 10 s for the powder to dissolve. The beaker was then removed from the microwave and the contents were stirred thoroughly until the powder had fully dissolved. Following this, an additional quantity of the drink was poured into the beaker up to the total weight required (150 g), the contents were stirred again, poured into a glass and chilled until required. Drug administration was again double-blind. using the JWT and consumption of caffeinated coffee. The two conditions were tested in counterbalanced order on two nonconsecutive days. Mood scales The main aim of the mood analysis was to investigate behaviour associated with withdrawal. Thus, mood evaluations were restricted to nine separate mood-related adjectives, each rated on 100mm unmarked line scales end-anchored ‘not at all’ and ‘extremely’, with adjectives centred above each line. The words used were ‘content’, ‘hungry’, ‘calm’, ‘vigour’, ‘fatigue’, ‘alert’, ‘drowsy’, ‘jittery’ and ‘headache’, all of which have been reported to be sensitive to the effects of caffeine and/or caffeine Drink and drug administration The quantity of caffeine/placebo was 150mg, with drug preparation and storage being identical to experiment 1. As cold drinks were used in this experiment, however, drink administration was different. Drinks were prepared by placing the contents of the relevant tube in a plastic beaker containing a small quantity of the drink (Sainsbury’s pure orange juice). This was then placed in a microwave for 10 s for the powder to dissolve. The beaker was then removed from the microwave and the contents were stirred thoroughly until the powder had fully dissolved. Following this, an additional quantity of the drink was poured into the beaker up to the total weight required (150 g), the contents were stirred again, poured into a glass and chilled until required. Drug administration was again double-blind. Procedure On two nonconsecutive days, participants reported to the laboratory at either 09.00 or 09.45 h, having been instructed to consume nothing but water since 23.00 h of the previous evening. The basic procedure was the same as experiment 1 up to the completion of the final mood ratings... Data analysis The data of one participant who failed to complete the second session were excluded from further analysis. Mood was analysed by separate MANOVA analyses of the nine mood items. Each of the two time periods following drug administration was contrasted separately, with baseline ratings as covariates, using deprivation state as the within-subjects factor and test order as the between-subjects factor.|
|How many outcome-specific endpoints are evaluated?||6|
|What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately)||anxiety|
|List additional health endpoints (separately).||jittery|
|List additional health endpoints (separately)||headache|
|Notes||Each experiment used different mood scale measures|
|What is the study design?||Controlled Trial|
|Randomized or Non-Randomized?||RCT|
|What were the diagnostics or methods used to measure the outcome?||Subjective|
|Optional: Name of Method or short description||Experiment 1 - Profile of Mood States (POMS) Experiment 2 - Visual analogue scale|
|Caffeine (general)||Caffeine (general)|
|What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.)||nondeprived (caffeine) vs deprived (placebo, no caffeine)|
|What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models. Copy from methods)||none|
|Provide a general description of results (as reported by the authors).||Experiment 1 - Mood Analysis of the data from the six POMS factors revealed no significant differences between the deprived and nondeprived groups (all P>0.1), which was against prediction. Experiment 2 - Mood Analysis of drowsy ratings demonstrated an effect of deprivation state at 45 min [F(1,16)=4.61, P<0.05], and at 60min after ingestion [F(1,16)=7.28, P<0.05]. Mean comparisons showed that in both cases ratings were lower when participants were nondeprived than when they were deprived (Fig. 2). In terms of headache ratings, a significant effect of deprivation state was also found at 60 min after the drink [F(1,16)=8.86, P<0.01], when mean comparisons revealed lower ratings on the day caffeine was consumed than following placebo (Table 5). Analysis of the remaining moods revealed no significant effects.|
|Did the authors perform a dose-response analysis (or trend/related analysis)?||No|
|What were the authors's observations re: trend analysis?|
|What were the author's conclusions?||(In experiment 2) It was also observed that compared to being nondeprived, deprived participants showed a tendency to be more withdrawn (higher headache and drowsy ratings). This finding is consistent with a number of previous studies (e.g. Richardson et al., 1995; Smit and Rogers, 2000). More importantly here, this shows that even though clear differences in withdrawal were produced by deprivation state, this did not influence attentional bias. This implies that negative mood states induced by caffeine deprivation do not relate to attentional bias.|
|What were the sources of funding?||This research was funded by the University of Sussex.|
|What conflicts of interest were reported?||N/A|
|Does the exposure (dose) need to be standardized to the SR?||No|
|Provide calculations/conversions for the exposure based on the decision tree in the guide (for all endpoints/exposure levels of interest).|
|List all the endpoint(s) followed by the dose (mg) which will be used in comparison to Nawrot. Characterize value as LOAEL/NOAEL, etc. if possible.||Anxiety - NOAEL = 100 mg Fatigue - NOAEL = 100 mg Confusion - NOAEL = 100 mg Drowsy - NOAEL = 150 mg Jittery - NOAEL = 150 mg Headache - NOAEL = 150 mg|
|Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot.||No effect was seen below the Nawrot comparison number. Ratings for drowsy and headache were significantly improved by caffeine.|
|What is the importance of the study with respect to the adverseness of the outcome?||Important|
No baseline characteristics have been defined for this extraction form.
Results & Comparisons
No Results found.
|Arm or Total||Title||Description||Comments|
No quality dimensions were specified.
No quality rating data was found.