Evaluating the Role of Expectations in Response to Caffeine Consumption: An RCT

Not Applicable

Completed

Conditions: Affect
Caffeine
Cognitive Ability, General
Mood

Interventions: Drug: Placebo
Drug: Caffeine

Registration Number: NCT02461693

Lead Sponsor: University of Alabama at Birmingham

Brief Summary: 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.

Detailed Description: Not available

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 205

Inclusion Criteria

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)

Exclusion Criteria

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

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Placebo	Placebo	One-time treatment with lactose-based placebo pill
Caffeine	Caffeine	One-time treatment with 200mg caffeine pill

Primary Outcome Measures

Name	Time	Method
Mood State Score on POMS-2 Test	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)	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	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	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