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Trial registered on ANZCTR


Registration number
ACTRN12618000115235
Ethics application status
Approved
Date submitted
17/01/2018
Date registered
29/01/2018
Date last updated
12/02/2020
Date data sharing statement initially provided
6/02/2019
Type of registration
Prospectively registered

Titles & IDs
Public title
The effects of Caffeine on Attentional Networks
Scientific title
The effects of Caffeine on Attentional Networks in Healthy Volunteers
Secondary ID [1] 293803 0
None
Universal Trial Number (UTN)
U1111-1207-9356
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Cognition (Attention) 306217 0
Condition category
Condition code
Neurological 305316 305316 0 0
Studies of the normal brain and nervous system

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Acute (1 day) oral ingestion of 200mg Caffeine (2 x capsules) with a one-week washout period. Adherence monitored via direct observation by study staff.
Intervention code [1] 300057 0
Treatment: Drugs
Comparator / control treatment
Acute (1 day) oral ingestion of corn flour (2 x capsules)
Control group
Placebo

Outcomes
Primary outcome [1] 304474 0
Behavioural performance (Reaction Time and Accuracy) on an Attentional Network Task and a Flanker Go/Nogo task
Timepoint [1] 304474 0
Pre-ingestion and 30 minutes Post ingestion (primary endpoint)
Primary outcome [2] 304475 0
Event-related measures of brain activity (Amplitude of the N1 ERP component) during the performance of an attentional network task, as measured by electroencephalography (EEG)
Timepoint [2] 304475 0
Pre-ingestion and 30 minutes Post-ingestion (Primary endpoint)
Primary outcome [3] 304476 0
Event-related measures of brain activity (Amplitude of the N2 ERP component) during the performance of an attentional network task and a flanker go/nogo task, as measured by electroencephalography (EEG)
Timepoint [3] 304476 0
Pre-ingestion and 30 minutes Post-ingestion (Primary endpoint)
Secondary outcome [1] 342069 0
Subjective measures of mood as assessed by the Profile of Mood States-Short Form (POMS) (Shacham, 1983). Present experience of 37 adjectives will be rated on a 5-point Likert scale from 0 (‘not at all’) to 4 (‘extremely’), resulting in a Total Mood Disturbance score (ranging from 0-148), and scores on the following subscales: Tension-Anxiety (0-24), Depression- Dejection (0-32), Anger-Hostility (0-28), Vigour-Activity (0-24), Fatigue-Inertia (0-20), Confusion-Bewilderment, (0-20). Higher scores are indicative of higher mood effect.
Timepoint [1] 342069 0
Pre-ingestion and 30 minutes Post-ingestion
Secondary outcome [2] 342070 0
The Karolinska Sleepiness Scale (KSS) will measure of subjective fatigue. This comprises of a nine-point scale ranging from 1 ‘extremely alert’ to 9 ‘extremely sleepy-fighting sleep’, with higher scores indicating greater fatigue.
Timepoint [2] 342070 0
Pre-ingestion and 30 minutes Post-ingestion
Secondary outcome [3] 342071 0
Visual Analogue Scales (VAS) will be used as subjective measures of drug effects. Participants will indicate their agreement with a statement (e.g., I feel alert’) by marking a 10cm horizontal line from ‘strongly disagree’ to ‘strongly agree’. The distance (cm) from the beginning of the line to the mark will be measured resulting in a score from 0 to 10 for each statement. The Subjective Drug Effects statements relate to: strength of drug effect, liking of drug effect, levels of alertness, and levels of intoxication.
Timepoint [3] 342071 0
Pre-ingestion and 30 minutes Post-ingestion
Secondary outcome [4] 342072 0
Certainty rating of caffeine consumption from 0% to 100%
Timepoint [4] 342072 0
30 minutes Post-ingestion
Secondary outcome [5] 342293 0
Visual Analogue Scales (VAS) will be used as subjective measures of performance. Participants will indicate their agreement with a statement (e.g., I feel alert’) by marking a 10cm horizontal line from ‘strongly disagree’ to ‘strongly agree’. The distance (cm) from the beginning of the line to the mark will be measured resulting in a score from 0 to 10 for each statement. The four Subjective Performance VAS statements are: feelings of alertness, ability to perform attentional tasks, perceived driving ability and current capacity to drive safely.
Timepoint [5] 342293 0
Pre-ingestion and 30 minutes Post-ingestion

Eligibility
Key inclusion criteria
Participation will be restricted to low caffeine users (less than 100mg per day) as assessed by the Caffeine and energy drink questionnaire.
Minimum age
18 Years
Maximum age
35 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Exclusion criteria will include serious physical or neurological conditions, current or notable past history of mental health conditions), current use of psychoactive medications, recent or notable past history of illicit drug use, daily tobacco use, risk of alcohol dependence as measured by the Alcohol Use and Disorders Identification Test (AUDIT; defined as >= 16), high levels of psychological distress measured by Kessler Psychological Scale (K10; defined as >= 30), or contraindications to caffeine such as hypertension or anxiety. All participants will have English as their first language and normal or corrected-to-normal vision and hearing. Females will be excluded if they are currently pregnant or if there is any chance that they may be pregnant.

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Identical capsules will be used for the caffeine and placebo conditions. Capsules will be provided to student researchers and participants in envelopes labelled according to participant number and session number only to protect blinding. Blinding will remain intact until the conclusion of recruitment.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Randomisation will be conducted by the Chief Investigator using an online randomisation program (randomization.com).
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
Intervention assignment
Crossover
Other design features
Fully within groups repeated measures
Phase
Phase 4
Type of endpoint/s
Efficacy
Statistical methods / analysis
Twenty participants, aged 18 to 35 years will be invited to participate. A power analysis (g*power) indicates that this sample size will be sufficient to detect a moderate effect size of f = .25 with power of .8.

Data analysis will be conducted using repeated measures ANOVA, with Greenhouse-geisser corrections where appropriate and Bonferoni adjusted pairwise comparisons for the analysis of any significant interaction effects (p < .05)
To investigate the effect of caffeine on reactive and active inhibitory control, a repeated measures ANOVA will be conducted on data from the flanker go/nogo task. The independent variables will be Caffeine Condition (0mg, 200mg), Time (pre-ingestion, post-ingestion), Trial Type (go, no-go), and Flanker Congruency (congruent, incongruent). Dependent variables will be accuracy (% of correct trials), reaction time (RT) and N2 amplitude at frontal electrode sites.
To investigate the effects for caffeine on alerting, orienting and executive control a repeated measures ANOVA will be conducted on data from the attentional network task. The independent variables will be Caffeine Condition (0mg, 200mg), Time (pre-ingestion, post-ingestion), Cue (none, central, spatial), and Flanker Congruency (congruent, incongruent). Dependent variables will be accuracy (% of correct trials), reaction time (RT) and N1 amplitude at occipital electrode sites.
To examine the effects of caffeine on subjective measures of mood (POMS), sleepiness (KSS) and drug effects (VAS), a repeated measures ANOVA will be conducted for each variable with the inclusion of the following factors: Caffeine Condition (0mg, 200mg), Time (pre-ingestion, post-ingestion).

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
1/03/2018
Actual
16/05/2018
Date of last participant enrolment
Anticipated
22/02/2019
Actual
29/05/2019
Date of last data collection
Anticipated
1/03/2019
Actual
30/06/2019
Sample size
Target
24
Accrual to date
Final
26
Recruitment in Australia
Recruitment state(s)
TAS

Funding & Sponsors
Funding source category [1] 298419 0
University
Name [1] 298419 0
University of Tasmania
Country [1] 298419 0
Australia
Primary sponsor type
University
Name
University of Tasmania
Address
Private Bag 30
Hobart, Tasmania, 7001
Country
Australia
Secondary sponsor category [1] 297558 0
None
Name [1] 297558 0
Address [1] 297558 0
Country [1] 297558 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 299415 0
University of Tasmania HREC - Health and Medical
Ethics committee address [1] 299415 0
Research Integrity and Ethics Unit | Office of Research Services
301 Sandy Bay Rd, Sandy Bay
Private Bag 1, Hobart TAS 7001
Ethics committee country [1] 299415 0
Australia
Date submitted for ethics approval [1] 299415 0
21/11/2017
Approval date [1] 299415 0
29/03/2018
Ethics approval number [1] 299415 0

Summary
Brief summary
This study will will address the gaps in the literature by exploring the underlying neural correlates of an acute dose of caffeine using both an attentional network task and a flanker Go/NoGo task. Specifically, caffeine is expected to improve the alerting and executive control networks of attention, but not the orienting network.
For the attentional network task, it is hypothesised there will be a reduction in reaction time and an increase brain activity (N1 amplitude) following alerting (central) but not orienting (spatial) cues after caffeine ingestion in comparison to placebo.
For the flanker go/nogo task, it is hypothesised that Reaction Time and brain activity (N2 amplitude) will be greater for incongruent relative to congruent trials, and that this flanker interference effect would be reduced from pre- to post-ingestion for caffeine relative to placebo.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 80326 0
Dr Allison Matthews
Address 80326 0
Lecturer in Psychology
Division of Psychology | School of Medicine
College of Health and Medicine
University of Tasmania
Hobart TAS 7001
Country 80326 0
Australia
Phone 80326 0
+61 3 6226 7236
Fax 80326 0
Email 80326 0
[email protected]
Contact person for public queries
Name 80327 0
Allison Matthews
Address 80327 0
Lecturer in Psychology
Division of Psychology | School of Medicine
College of Health and Medicine
University of Tasmania
Hobart TAS 7001
Country 80327 0
Australia
Phone 80327 0
+61 3 6226 7236
Fax 80327 0
Email 80327 0
[email protected]
Contact person for scientific queries
Name 80328 0
Allison Matthews
Address 80328 0
Lecturer in Psychology
Division of Psychology | School of Medicine
College of Health and Medicine
University of Tasmania
Hobart TAS 7001
Country 80328 0
Australia
Phone 80328 0
+61 3 6226 7236
Fax 80328 0
Email 80328 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
no arrangements have been made for this


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.