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Study Title and Description

Effects of caffeine on performance of low intensity tasks.



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 on performance of low intensity tasks.
Author WH Scott,KM Coyne,MM Johnson,CG Lausted,M Sahota,AT Johnson,
Country
Year 2002
Numbers

Secondary Publication Information
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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 12027348
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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)? The present investigation employed 12 different tasks to assess simple responses (Wilkinson and Choice Reaction Time), basic mathematics (Serial Addition/Subtraction), short-term memory processing (Column Addition), recognition of incongruous stimuli (Logical Reasoning), hand-eye coordination, spatial differentiation (Perfection), and object manipulation (Superfection). A caffeine dose of 5 mg/kg of body weight was selected for this project. This dosage is somewhat higher than those previously reported in other studies; however, it was our belief that this dosage was necessary to assess whether caffeine would stimulate performance.
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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) Orientation Thirty-one college age men and women participated. All subjects were nonsmokers and consumed less than three caffeine beverages per week. All subjects were instructed to abstain from all caffeinated products for at least 24 hours prior to a scheduled test session. Subjects were required to report to the laboratory on three separate visits of which the first was for orientation and successive visits designed to test the placebo and caffeine treatments. The orientation visit was a 1-hr. session in which subjects received both verbal and written instructions for executing the various tasks. Practice trials were conducted by all subjects immediately after they received the task instructions. The practice order is displayed in Table 1. Treatment Sessions Test beverages were administered using a double blind design in which both the subject and tester were naive to the beverage content. One half of the subjects received the caffeine beverage before the placebo, and the other half received the placebo first to minimize training effects on task performance. Orange juice (400 ml) was used as the base ingredient in both test beverages (placebo and caffeine) and was the only substance in the placebo beverage. The caffeine beverage was re pared by supplementing the orange juice with Vivarin (SmithKlme Beecham, Pittsburgh, PA), which contains approximately 200 mg of caffeine per tablet. The Vivarin tablet was weighed to create a conversion chart containing the caffeine dose weight equivalent to 5 rng/kg of body weight. Tablets were crushed into powder in advance and added to the test beverage based on this weight conversion chart. Subjects did not report being able to differentiate between the two test beverages. Testing was initiated 30 min, after subjects consumed the entire treatment beverage to allow full dissipation of caffeine throughout the body. It has been reported that peak levels may be obtained within 30 minutes after consumption (Barraclough & Beech, 1995). Anxiety measurements were assessed prior to administering the test beverage using the state-anxiety subscale of the State-Trait Anxiety Inventory (Spielberger,Gorsuch, & Luchene, 1970). This test attempts to draw conclusions with respect to state anxiety based on an individual's responses to a series of subjective statements. On this test, the subject was presented statements along with positive, neutral, and negative responses. Subjects were instructed to select a response to the question that is closest to their subjective feeling at that particular moment. This test was repeated again when subjects had completed the various tasks.
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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 state anxiety
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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? RCT
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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 State-Trait Anxiety Inventory. This test attempts to draw conclusions with respect to state anxiety based on an individual's responses to a series of subjective statements. On this test, the subject was presented statements along with positive, neutral, and negative responses. Subjects were instructed to select a response to the question that is closest to their subjective feeling at that particular moment.
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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 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 (0 mg caffeine) vs 5 mg/kg caffeine subjects were their own controls,
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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) None listed
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Provide a general description of results (as reported by the authors). State Anxiety Pre and posttest state anxiety scores, recorded for both the placebo and caffeine treatments, were similar at both times in the placebo treatment. In contrast, state anxiety values at posttest exceeded those at pretest in the caffeine treatment and also were significantly greater than those in the placebo treatment at pretest and also at posttest.
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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? The caffeine treatment significantly affected scores on state anxiety almost immediately after consumption and persisted through the hour of testing as indicated by posttest scores. Similar findings for increased anxiety with caffeine (2 and 4 mg/kg) have been reported by Liguori, Grass, and Hughes (1999). These authors also reported that subjects stated they felt more energetic, confident, and vigorous, yet performance was not changed on several simple tasks, perhaps because the tasks were too easy.
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What were the sources of funding? None listed
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What conflicts of interest were reported? None listed
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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). 5 mg/kg * 80 kg adult = 400 mg
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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 (state) - LOAEL = 400 mg
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Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. single dose
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What is the importance of the study with respect to the adverseness of the outcome? Important
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