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Study Title and Description

Effects of caffeine in overnight-withdrawn consumers and non-consumers.



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*?
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Primary Publication Information
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TitleData
Title Effects of caffeine in overnight-withdrawn consumers and non-consumers.
Author AP Smith,G Christopher,D Sutherland,
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Extraction Form: Behavior - Design Details - INCLUDED Studies
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Design Details
Question... Follow Up Answer Follow-up Answer
Refid 16910172
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What outcome is being evaluated in this paper? Behavior
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What is the objective of the study (as reported by the authors)? To compare the effects of 2 mg/kg caffeine on mood and cognitive performance in overnight-withdrawn consumers and non-consumers of caffeine.
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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 Information should be extracted based on relevance to the SR (i.e., caffeine related methods) Twenty-five overnight-withdrawn consumers and twenty-five non-consumers of caffeine were tested in a withinsubjects design where they were given a drink containing 2 mg/kg caffeine on one test day and placebo on another test day. The order of conditions (caffeine/placebo) was counterbalanced. Mood and performance measures were taken before and after each drink, and pre-drink measures were used as covariates in the analysis of post-drink measures. Mood. Mood was measured at both the start (Mood 1) and the end (Mood 2) of the task battery using 18 visual analogue mood scales each comprising a pair of adjectives (drowsy–alert, happy–sad, etc.) presented on the computer screen. Participants moved the cursor from a central position to a position representative of their current mood state. Three mood factors were derived from the scales: alertness (max. score 400), hedonic tone (max. score 300) and anxiety (max. score 150; low score is higher anxiety).
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How many outcome-specific endpoints are evaluated? 1
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) anxiety
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List additional health endpoints (separately).
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List additional health endpoints (separately)
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Notes also measured alertness and hedonic tone
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Clinical
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Physiological
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Other
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What is the study design? Controlled Trial
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Randomized or Non-Randomized? NCT
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What were the diagnostics or methods used to measure the outcome? Subjective
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Optional: Name of Method or short description measured using a visual analogue scale
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Caffeine (general) Caffeine (general)
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Coffee
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Chocolate
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Energy drinks
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Gum
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Medicine/Supplement
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Soda
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Tea
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Measured Measured
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Self-report
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Children
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Adolescents
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Adults Adults
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Pregnant Women
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What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) placebo (no caffeine) vs 2 mg/kg caffeine
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What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models.  Copy from methods) N/A
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Provide a general description of results (as reported by the authors). Mood 1 (30 min after drink, before starting performance tests). Caffeine increased alertness relative to placebo [F(1,45) = 6.39, P , 0.05]. There was no main effect for consumer group and no group x condition interaction (see Figure 1). There were no significant differences for anxiety or hedonic tone (see Table II). Mood 2 (end of task battery). Caffeine increased both alertness [F(1,45) = 28.54,P , 0.0001—see Figure 7] and hedonic tone [F(1,45) = 13.3, P < 0.001—see Figure 8] relative to placebo. The effect of caffeine on alertness was greater in the non-consumers which led to a significant interaction between consumer group and caffeine conditions [F(1,45) = 4.24, P < 0.05]. There was also an interaction between consumer group and caffeine conditions [F(1,45) = 5.33, P < 0.05] with caffeine reducing anxiety in the consumers but increasing it in the non-consumers (see Table II).
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Did the authors perform a dose-response analysis (or trend/related analysis)? No
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What were the authors's observations re: trend analysis?
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What were the author's conclusions? In the present study the three measures that did show interactions between consumer status and caffeine conditions (long responses in the categoric search task; post-performance ratings of alertness; and post-performance ratings of anxiety) all showed that non-consumers showed greater effects of caffeine than withdrawn consumers. As these measures were not influenced by caffeine withdrawal one can interpret the results in terms of regular consumption influencing certain effects of caffeine. The general consistency of the other effects of caffeine across subject groups is not consistent with the withdrawal hypothesis proposed by James (1994). The present results confirm the findings of Haskell et al. (2005) and Hewlett and Smith (in press).
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What were the sources of funding? The research described in this paper was supported by the Economic and Social Research Council (grant number: R022250203). Some of the Professor Smith’s caffeine research has been supported by the Institute for Scientific Information on Coffee.
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What conflicts of interest were reported? N/A
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Does the exposure (dose) need to be standardized to the SR? Multiple metrics
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Provide calculations/conversions for the exposure based on the decision tree in the guide (for all endpoints/exposure levels of interest). 2 mg/kg administration (no body weight assigned by authors) 80 kg = average adult body weight = 160 mg/day
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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 - LOAEL = 160 mg/day (non-consumers) Anxiety - NOAEL = 160 mg/day (consumers)
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Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. single dose the adverse effect on anxiety (increase) was only seen in non-consumers and only after testing; whereas at the same time point consumers noted a decrease in anxiety. no effect was seen in either group 30 min after consumption.
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What is the importance of the study with respect to the adverseness of the outcome? Important
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