Evaluating the Role of Expectations in Response to Caffeine Consumption: A Randomized Control Trial
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 205
- 主要终点
- Mood State Score on POMS-2 Test
研究概览
简要总结
The purpose of this project is to examine the effect of expectancy on mood and alertness after consumption of caffeine "treatment" or placebo "control" pill, given that participants know their probability for receiving the caffeine versus placebo pill. Participants will be randomly assigned a probability (ranging from 0-100%) of receiving caffeine vs. placebo, and this probability will be revealed to them before consumption of the assigned pill and subsequent cognitive testing. At the time of consumption, neither study staff administering the intervention nor participants will know for certain which pill is given to each participant. Pill assignment will depend on pre-determined randomization probabilities, which will be provided and assigned by the study statistician. By revealing participants' individual probability of receiving the caffeine pill, we will induce positive or negative expectancies regarding likelihood for receipt of the caffeine pill. These experimental manipulations will: 1) estimate the effect of expectancy on cognitive and affective outcomes, and 2) allow for a more direct estimate of the effect of the caffeine pill under real-world conditions than would a conventional randomized trial.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Other
- 盲法
- Double (Participant, Investigator)
盲法说明
Participants, study personnel interacting with participants, and investigators were blinded. Only the study statistician knew treatment assignments.
入排标准
- 年龄范围
- 18 Years 至 —(Adult, Older Adult)
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •18 years-old or older
- •available to participate on the dates specified
- •willing to take a caffeine or placebo pills at study session
- •willingness to abstain from caffeine for 12 hours prior to study visit (8:30pm-8:30am)
- •UAB employees or students with some college education (including current enrollment)
排除标准
- •self-reported use of ADHD medication
- •self-reported use of anxiety medication
- •self-reported use of sleep medication
- •self-reported use of nicotine products
- •self-reported lactose intolerance
- •self-reported uncorrected vision
- •self-reported pregnancy or trying to become pregnant
研究组 & 干预措施
Caffeine
One-time treatment with 200mg caffeine pill
干预措施: Caffeine (Drug)
Placebo
One-time treatment with lactose-based placebo pill
干预措施: Placebo (Drug)
结局指标
主要结局
Mood State Score on POMS-2 Test
时间窗: 30 minutes post pill consumption
Profile of Mood States (POMS-2)- "Volunteers rated a series of 65 mood-related adjectives with regard to how they were feeling "right now" on a scale of 0 (not at all) to 4 (extremely). The adjectives factor into six mood sub-scales: Tension-Anxiety; Depression-Dejection; Anger-Hostility; Vigor-Activity; Fatigue-Inertia; Confusion-Bewilderment and a Total Mood Disturbance score which aggregates the six sub-scales into a single variable." - from our publication. The minimum and maximum possible raw scores were: 0 and 40 for Tension-Anxiety, 0 and 52 for Depression-Dejection, 0 and 44 for Anger-Hostility, 0 and 36 for Vigor-Aactivity, 0 and 24 for Fatigue-Inertia, 0 and 40 for Confusion-Bewilderment, -36 and 200 for Total Mood Disturbance, and 0 and 24 for Friendliness. For Friendliness and Vigor-Activity, the more positively a person feels, the higher the score. For all other sub-scales and Total Mood Disturbance, the more negatively a person feels, the higher the score.
Vigilance Score on Computer-based Test Using Random, Visual Stimulus: Proportion Correct (Out of 60)
时间窗: 45 to 105 minutes post pill consumption
Scanning Visual Vigilance Test. "This test assesses vigilance, ability to sustain attention during long, boring, continuous tasks that generate minimal cognitive load (Fine et al, 1994; Lieberman et al, 1998; 2002). The volunteer continuously scans a computer screen to detect an infrequent, difficult-to-detect stimulus that appears at random intervals and locations for 2 s. On average, a stimulus was presented once per minute. Upon detection of the stimulus, the volunteer pressed the space bar as rapidly as possible. Whether a stimulus was detected and time required for detection was recorded. Responses before or after stimulus occurrence were false alarms. The test lasted 60 minutes." - from our publication
Vigilance Score on Computer-based Test Using Random, Visual Stimulus: Number Correct, Number of False Alarm Hits
时间窗: 45 to 105 minutes post pill consumption
Scanning Visual Vigilance Test. "This test assesses vigilance, ability to sustain attention during long, boring, continuous tasks that generate minimal cognitive load (Fine et al, 1994; Lieberman et al, 1998; 2002). The volunteer continuously scans a computer screen to detect an infrequent, difficult-to-detect stimulus that appears at random intervals and locations for 2 s. On average, a stimulus was presented once per minute. Upon detection of the stimulus, the volunteer pressed the space bar as rapidly as possible. Whether a stimulus was detected and time required for detection was recorded. Responses before or after stimulus occurrence were false alarms. The test lasted 60 minutes." - from our publication
Vigilance Score on Computer-based Test Using Random, Visual Stimulus: Mean Time to a Correct Hit
时间窗: 45 to 105 minutes post pill consumption
Scanning Visual Vigilance Test. "This test assesses vigilance, ability to sustain attention during long, boring, continuous tasks that generate minimal cognitive load (Fine et al, 1994; Lieberman et al, 1998; 2002). The volunteer continuously scans a computer screen to detect an infrequent, difficult-to-detect stimulus that appears at random intervals and locations for 2 s. On average, a stimulus was presented once per minute. Upon detection of the stimulus, the volunteer pressed the space bar as rapidly as possible. Whether a stimulus was detected and time required for detection was recorded. Responses before or after stimulus occurrence were false alarms. The test lasted 60 minutes." - from our publication
次要结局
未报告次要终点
研究者
David Allison, Phd
Associate Dean for Science, School of Public Health
University of Alabama at Birmingham
