Study Title and Description
Central and peripheral effects of sustained caffeine use: tolerance is incomplete.
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||Central and peripheral effects of sustained caffeine use: tolerance is incomplete.|
|Author||J Watson,I Deary,D Kerr,|
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)?||This study was designed to investigate the effects of chronic, staggered caffeine ingestion on the responses of an acute caffeine challenge, during -euglycaemia.|
|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)||Twelve healthy volunteers were randomized using a double-blind, cross-over design to take either 200 mg caffeine (C-replete) or placebo (C-naïve) twice daily for 1 week. On the morning of a study, subjects were admitted at 09.00 h, having fasted overnight. At this time, subjects completed a questionnaire scoring the strength of 32 symptoms relating to caffeine-withdrawal rated on a scale of 0–3. Following baseline measurements being made, the responses to 200 mg caffeine (blood-pressure, middle cerebral artery velocity, mood and cognitive performance) were examined over the subsequent 120 min. Blood glucose was not allowed to fall below 4.0 mmol l-1. Mood using the UWIST mood score  consisting of 24 adjectives divided into three equal groups describing hedonic (pleasurable), tense and energetic mood: maximum score for each aspect is 32 each item is scored 1–4.|
|How many outcome-specific endpoints are evaluated?||1|
|What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately)||tense mood|
|List additional health endpoints (separately).|
|List additional health endpoints (separately)|
|Notes||withdrawal was the focus of the study|
|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||questionnaire scoring the strength of 32 symptoms relating to caffeine-withdrawal and Mood using the UWIST mood score consisting of 24 adjectives divided into three equal groups describing hedonic (pleasurable), tense and energetic mood: maximum score for each aspect is 32 each item is scored 1–4.|
|Caffeine (general)||Caffeine (general)|
|What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.)||placebo (0 mg caffeine) vs 200 mg caffeine|
|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|
|Provide a general description of results (as reported by the authors).||Caffeine withdrawal questionnaires showed no difference in total scores after caffeine abstinence or supplementation for 7 days (26.9±2.5 C-naïve vs 27.8 ± 2.3 C-replete, P = 0.34).Tense mood was most affected by caffeine status (Figure 3). Baseline measurements were significantly different (11.6±0.6 C-naïve vs 16.3 ± 1.6 C-replete, P<0.01). Caffeine consumption in the C-replete state was associated with a greater decrease in tense mood (-1.1 [-2.6, -0.34] C-naïve vs -4.7 [-7.5, -1.9] C-replete, P < 0.02).|
|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?||Interestingly daily caffeine consumption was associated with an increase in tense mood, which resolved after further caffeine consumption. It was only this aspect of mood that was associated with a significantly different response to the caffeine challenge between the two conditions.|
|What were the sources of funding?||None reported|
|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.||tense mood: NOAEL = 200 mg|
|Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot.||Single dose no effect observed below Nawrot (400 mg). In fact, 200 mg caffeine reduced tense mood in subjects who had been taking caffeine daily, prior to the experiment though their baseline anxiety before receiving the dose was higher than those subjects who were completely withdrawn.|
|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.