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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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Caffeine | Experimental | One-time treatment with 200mg caffeine pill |
|
| Placebo | Placebo Comparator | One-time treatment with lactose-based placebo pill |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Caffeine | Drug | 200mg delivered as pill; one-time dose |
| |
| Placebo |
| Measure | Description | Time Frame |
|---|---|---|
| Mood State Score on POMS-2 Test | 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. | 30 minutes post pill consumption |
| Vigilance Score on Computer-based Test Using Random, Visual Stimulus: Proportion Correct (Out of 60) | 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 | 45 to 105 minutes post pill consumption |
| Vigilance Score on Computer-based Test Using Random, Visual Stimulus: Number Correct, Number of False Alarm Hits | 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 |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| David B Allison, PhD | University of Alabama at Birmingham | Principal Investigator |
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| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 28406674 | Result | George BJ, Li P, Lieberman HR, Pavela G, Brown AW, Fontaine KR, Jeansonne MM, Dutton GR, Idigo AJ, Parman MA, Rubin DB, Allison DB. Randomization to randomization probability: Estimating treatment effects under actual conditions of use. Psychol Methods. 2018 Jun;23(2):337-350. doi: 10.1037/met0000138. Epub 2017 Apr 13. |
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Raw de-identified data will be posted as a replication data set on ICPSR after publication of results in a journal. Data will be free to download and accessible to anyone with access to ICPSR replication data sets.
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| ID | Title | Description |
|---|---|---|
| FG000 | Caffeine | One-time treatment with 200mg caffeine pill Caffeine: 200mg delivered as pill; one-time dose |
| FG001 | Placebo | One-time treatment with lactose-based placebo pill Placebo |
| Title | Milestones | Reasons Not Completed | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Overall Study |
|
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| ID | Title | Description |
|---|---|---|
| BG000 | Caffeine | One-time treatment with 200mg caffeine pill Caffeine: 200mg delivered as pill; one-time dose |
| BG001 | Placebo | One-time treatment with lactose-based placebo pill Placebo |
| Units | Counts |
|---|---|
| Participants |
|
| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Continuous | 5 participants (3 assigned to caffeine and two assigned to placebo) were deemed ineligible for study after participation and were thus excluded from the analysis |
| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | Mood State Score on POMS-2 Test | 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. | Results are of raw data as presented in our publication | Posted | Mean | Standard Error | units on a scale | 30 minutes post pill consumption |
|
Three months
No adverse events were reported
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| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | Caffeine | One-time treatment with 200mg caffeine pill Caffeine: 200mg delivered as pill; one-time dose |
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Please refer to our publication in Psyhcological Methods
| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Dr. David Allison, PI | University of Alabama at Birmingham | 205-975-9169 | dallison@uab.edu |
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| ID | Term |
|---|---|
| D002110 | Caffeine |
| ID | Term |
|---|---|
| D014970 | Xanthines |
| D000470 | Alkaloids |
| D006571 | Heterocyclic Compounds |
| D011688 | Purinones |
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Participants, study personnel interacting with participants, and investigators were blinded. Only the study statistician knew treatment assignments.
| Drug |
Lactose-based pill; one-time dose |
|
| 45 to 105 minutes post pill consumption |
| Vigilance Score on Computer-based Test Using Random, Visual Stimulus: Mean Time to a Correct Hit | 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 | 45 to 105 minutes post pill consumption |
| BG002 | Total | Total of all reporting groups |
| Mean |
| Standard Deviation |
| years |
|
| Sex: Female, Male | 5 participants (3 assigned to caffeine and two assigned to placebo) were deemed ineligible for study after participation and were thus excluded from the analysis | Count of Participants | Participants |
|
| Ethnicity (NIH/OMB) | 5 participants (3 assigned to caffeine and two assigned to placebo) were deemed ineligible for study after participation and were thus excluded from the analysis | Count of Participants | Participants |
|
| Race (NIH/OMB) | 5 participants (3 assigned to caffeine and two assigned to placebo) were deemed ineligible for study after participation and were thus excluded from the analysis | Count of Participants | Participants |
|
| Title |
|---|
| Description |
|---|
| OG000 | Caffeine | One-time treatment with 200mg caffeine pill Caffeine: 200mg delivered as pill; one-time dose |
| OG001 | Placebo | One-time treatment with lactose-based placebo pill Placebo |
|
|
| Primary | Vigilance Score on Computer-based Test Using Random, Visual Stimulus: Proportion Correct (Out of 60) | 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 | One participant who received the caffeine pill had to use the restroom during the vigilance testing period and had to stop the test. Due to a technicality of the computer program, her data for the vigilance test was not available for analysis. | Posted | Mean | Standard Error | Proportion correct | 45 to 105 minutes post pill consumption |
|
|
|
| Primary | Vigilance Score on Computer-based Test Using Random, Visual Stimulus: Number Correct, Number of False Alarm Hits | 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 | One participant who received the caffeine pill had to use the restroom during the vigilance testing period and had to stop the test. Due to a technicality of the computer program, her data for the vigilance test was not available for analysis. | Posted | Mean | Standard Error | counts | 45 to 105 minutes post pill consumption |
|
|
|
| Primary | Vigilance Score on Computer-based Test Using Random, Visual Stimulus: Mean Time to a Correct Hit | 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 | One participant who received the caffeine pill had to use the restroom during the vigilance testing period and had to stop the test. Due to a technicality of the computer program, her data for the vigilance test was not available for analysis. | Posted | Mean | Standard Error | seconds | 45 to 105 minutes post pill consumption |
|
|
|
| 0 |
| 103 |
| 0 |
| 103 |
| EG001 | Placebo | One-time treatment with lactose-based placebo pill Placebo | 0 | 102 | 0 | 102 |
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| D011687 |
| Purines |
| D006574 | Heterocyclic Compounds, 2-Ring |
| D000072471 | Heterocyclic Compounds, Fused-Ring |