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Study Title and Description

Cognitive and psychomotor performance, mood, and pressor effects of caffeine after 4, 6 and 8 h caffeine abstinence.



Key Questions Addressed
1 For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on cardiovascular outcomes?
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Primary Publication Information
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TitleData
Title Cognitive and psychomotor performance, mood, and pressor effects of caffeine after 4, 6 and 8 h caffeine abstinence.
Author SV Heatherley,RC Hayward,HE Seers,PJ Rogers,
Country
Year 2005
Numbers

Secondary Publication Information
There are currently no secondary publications defined for this study.


Extraction Form: Cardiovascular Design
Design Details
Question... Follow Up Answer Follow-up Answer
What outcome is being evaluated in this paper? Cardiovascular
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What is the objective of the study (as reported by the authors)? The aim of this study was to measure the effects on psychomotor and cognitive performance, mood, hand steadiness, blood pressure and heart rate of caffeine administration after periods of 4, 6, and 8 h of caffeine abstinence.
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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) Methods Participants Forty-nine participants (27 female) aged between 18 and 34 years took part in the study. They were all students at the University of Bristol. The participants were moderate to high caffeine consumers, all consuming at least three cups of tea or coffee a day (this information was gathered by e-mail before the participants had been recruited to the study). They were either nonsmokers or light to moderate smokers and reported that they had no food sensitivities and were not pregnant or breastfeeding. Study Design and Procedure The basic design of the study can be summarised as follows. On two separate occasions, three groups of participants (n=16, n=16 and n=17) were deprived of caffeine overnight, until being given 1.2 mg/kg caffeine at either 9 A.M., 11 A.M. or 1 P.M. At 5 P.M. they received caffeine (1.2 mg/kg) or placebo. Within each group, half of the participants received caffeine on the first occasion and placebo on the second, with the other participants receiving placebo first and caffeine second. Immediately before and 30 min after 5 P.M. measurements were taken to assess participants’ mood, cognitive performance, hand steadiness, etc. Therefore, abstinence interval (4 versus 6 versus 8 h) was a between-subjects variable, and caffeine treatment was a within-subjects variable. Caffeine (versus placebo) was administered double blind in a lemon squash drink, and participants were randomised to abstinence interval group and treatment order (with the restriction that the various subgroups should be of a similar size and gender ratio). Participants attended at the same times on two separate days exactly 1 week apart. Participants were asked to refrain from consuming any caffeine-containing drink or food (e.g. coffee, tea, cola, Red Bull and chocolate drinks or products) from 10 P.M. the previous evening until the end of each test day. They were told that this was a standard request in all food and drink studies to ensure that caffeine did not play an uncontrolled role in any of the effects of the squash drinks. For all participants, the main part of testing started at 4 P.M. Blood pressure, heart rate and hand steadiness measurements were taken. Participants were then shown to their individual booths where they completed the battery of mood ratings and cognitive tasks. These constituted the baseline (i.e. pretreatment) measurements. At 5 P.M. participants consumed the lemon squash drink containing either 1.2 mg/kg caffeine or no caffeine (placebo). A rest period of half an hour followed, after which the full array of measurements was repeated (post-treatment measurements). Drug Administration Caffeine was administered double blind in 250 ml of lemon squash (Lemon Squash, Sainsbury’s Supermarket Ltd., UK, diluted according to the manufacturer’s instructions). Varying amounts of food grade caffeine hydrochloride were dissolved in this drink so that individual participants received 1.2 mg caffeine per kilogram body weight. The placebo drink was the same volume of lemon squash drink, without caffeine. Test Battery Systolic and diastolic blood pressure and heart rate were measured using the Omron 711 Intellisense automatic inflation monitor (Omron Healthcare UK, West Sussex, UK). Data Analysis For each dependent variable, the effect of caffeine was calculated for each interval using the formula (xCafter−xCbefore)−(xPafter−xPbefore), where x is the dependent variable, C is caffeine, P is placebo, after refers to post-treatment (i.e. the measurements made starting at 5:30 P.M., 30 min after the ingestion of caffeine or placebo) and before refers to pretreatment (i.e. the measurements made before the ingestion of caffeine or placebo). These ‘caffeine effect’ data (means±SEs) were tabulated, together with the results of ANOVA testing for the overall effect of caffeine and the interaction of the effect of caffeine and interval. Order of treatment (caffeine first, placebo second or vice versa) was included as a between-subjects factor in these analyses. Where appropriate, ANOVA with caffeine and order of treatment as factors was used to test for effects of caffeine within interval groups. Results with P values <0.05 were considered to be statistically significant.
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How many outcome-specific endpoints are evaluated? 2
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Blood pressure (SBP, DBP)
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List additional health endpoints (separately). 2 Heart rate
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List additional health endpoints (separately).3
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List additional health endpoints (separately).4
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List additional health endpoints (separately).5
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List additional health endpoints (separately).6
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Clinical, physiological, other Physiological
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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? Objective
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Optional: Name of Method or short description Systolic and diastolic blood pressure and heart rate were measured using the Omron 711 Intellisense automatic inflation monitor (Omron Healthcare UK, West Sussex, UK).
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Caffeine (general) Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other?
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Measured or self reported? Measured
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Children, adolescents, adults, or pregnant included? Adults
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What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) Subjects served as 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
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What conflicts of interest were reported? The views expressed in this paper are the sole responsibility of the authors and do not necessarily reflect the views of the European Commission or its services or their future policy in this area.
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Refid 15696321
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What were the sources of funding? This research was supported by a grant from the European Union Fifth Framework Programme (grant no. QLK1-2000-00069).
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Results & Comparisons

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