Study Title and Description
Gender differences in subjective and physiological responses to caffeine and the role of steroid hormones
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||Gender differences in subjective and physiological responses to caffeine and the role of steroid hormones|
|Author||J. L. Temple and A. M. Ziegler|
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)?||The purpose of this study was to test the hypothesis that differences in circulating steroid hormones mediate gender differences in response to caffeine.|
|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)||Participants and Recruitment Participants were 15 males and 9 females with an average age of 15.6 – 0.12 years, recruited through direct mailings, flyers distributed at local middle and high schools, as well as flyers posted around the University at Buffalo and the surrounding community. Eligibility criteria included the following: previous ingestion of caffeine without adverse reactions, having signs of pubertal maturation, not using hormone based contraceptives, not smoking, not taking medication known to have interactions with caffeine, and willingness to visit the laboratory on four occasions for 90 minutes each. General Experimental Procedures Qualifying males were scheduled for four visits, 2 weeks apart. Females were asked to schedule their first and third visits to our laboratory within 3–8 days from day 1 of menstruation (follicular phase). Their second and fourth visits were scheduled 2 weeks later (luteal phase). Participants were provided a list of caffeine-containing products from which to abstain for 24 hours before their scheduled appointment and were instructed not to not eat or drink anything other than water for 2 hours before the session. Participants were also asked to refrain from engaging in physical activity on the day of each laboratory visit. To remove subject expectations about the effects of caffeine, participants were told that the beverage they would be consuming ‘‘may have levels of one or more of the following substances manipulated: sugar, aspartame, Splenda, caffeine, or artificial coloring.’’ This deception was considered acceptable because it involved no greater than minimal risk, and was necessary to prevent potential preconceptions of caffeine’s effects from altering experimental results. Participants then completed a same-day and previous-day dietary recall to confirm caffeine abstinence. Participants then provided a 3-mL saliva sample into a sterile tube that was analyzed for steroid hormones. Next, the participant completed the ‘‘caffeine consumption questionnaire’’ to determine caffeine use habits. The participant then had baseline blood pressure and heart rate readings taken. Then, the participant consumed a 350mL portion of Sprite, lemonade, or orange juice, containing either placebo or caffeine (2 mg/kg). Participants received two doses each of placebo and caffeine over the course of four separate visits. Before the first visit, participants were randomized to receive caffeine or placebo first and subsequent drug administration was counterbalanced. Caffeine and beverage preparation Caffeine and placebo treatments were prepared by an experimenter who was not involved in the data collection for this study. Caffeine was added to Sprite to mask its bitter taste and heated to 140oF and stirred for 25 minutes. Flattened Sprite without added caffeine was used as the placebo. The caffeine or placebo solutions were then aliquoted into 14-mL vials, labeled A or B, and frozen. On the day of the visit, the appropriate vial was thawed for >1 hour at room temperature. Participants were able to choose to drink orange juice, lemonade, or Sprite, which are all caffeine free. We verified that this dose of caffeine could not reliably be detected by taste in a previous study. While the participant was providing a saliva sample and completing questionnaires, the researcher prepared a mixture of 350mL of the chosen beverage and volume of A or B equivalent to 2mg caffeine/kg body weight. Profile of mood states. This version of the POMS measures eight dimensions of affect or mood, including anxiety, depression, anger, vigor, fatigue, confusion, friendliness, and elation. Each was assessed on a 5-point Likert Scale, with 1 being ‘‘not at all’’ and 5, ‘‘extremely.’’ Within these eight areas are twomood super-scales: arousal and positive mood|
|How many outcome-specific endpoints are evaluated?||5|
|What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately)||Anxiety|
|List additional health endpoints (separately).||Confusion|
|List additional health endpoints (separately)|
|Notes||POMS questionnaire also measured vigor, friendliness, and elation.|
|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||Profile of Mood States (POMS)|
|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 2mg caffeine/kg body weight. Each participant served as his/her own control (placebo)|
|What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models. Copy from methods)||POMS were analyzed using mixed effects regression models with gender, and caffeine use (mg/day) as time invariant predictors and time (from 10 to 60 minutes after drug administration), drug treatment (placebo vs. caffeine), and steroid hormone levels as time variant predictors and baseline blood pressure and heart rate as covariates. To correct for multiple comparisons on the POMS, a Bonferroni correction was applied here as well and data were only considered significant if p < 0.006.|
|Provide a general description of results (as reported by the authors).||There were trends for effects of caffeine administration and gender on the arousal ( p = 0.006 and p = 0.008, respectively) and fatigue ( p = 0.017 and p = 0.03, respectively) subscales of the POMS as well as trends for interactions between gender and caffeine administration on scores on the vigorous (p = 0.04), fatigue (p = 0.04), and arousal (p = 0.01) subscales of the POMS. However, after the Bonferroni correction was applied, none of these remained significantly different. There were no significant interactions when steroid hormone levels were included in the model (all p > 0.08).|
|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?||No mood specific conclusions.|
|What were the sources of funding?||This research was supported by a grant from the National Institute on Drug Abuse (KO1DA021759) to J.L.T.|
|What conflicts of interest were reported?||Neither author of this article has any conflicts of interest to report.|
|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.||Confusion - NOAEL = 2 mg/kg Anger - NOAEL = 2 mg/kg Depression - NOAEL = 2 mg/kg Fatigue - NOAEL = 2 mg/kg Anxiety - NOAEL = 2 mg/kg|
|Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot.||There was a trend for an effect of 2 mg/kg caffeine and gender on fatigue but after Bonferroni correction these were not significant.|
|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.