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Trial registered on ANZCTR


Registration number
ACTRN12614001190695
Ethics application status
Approved
Date submitted
23/10/2014
Date registered
12/11/2014
Date last updated
27/01/2016
Type of registration
Prospectively registered

Titles & IDs
Public title
Does executive function training buffer against self-control depletion? The case of eating behaviour.
Scientific title
Does executive function training buffer against self-control depletion to reduce unhealthy food intake, compared to an active control?
Secondary ID [1] 285539 0
none
Universal Trial Number (UTN)
U1111-1163-3010
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
overweight/obesity 293357 0
Condition category
Condition code
Diet and Nutrition 293632 293632 0 0
Obesity

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
A 2 (executive function training/placebo training) x 2 (depletion/no depletion) factorial design will be used to test whether executive function training buffers against the negative effects of depletion on eating behaviour. Therefore, there will be four conditions: 1) executive function training followed by depletion; 2) executive function training followed by no depletion; 3) placebo training followed by depletion; 4) placebo training followed by no depletion.

Following this, behaviour will be measured via a 'taste-test'. Participants will be informed that they are completing an unrelated experiment in which they have to rate a new flavour of a particular snack food (e.g. chocolate). Participants will be left alone with a bowl of the snack food and asked to rate this food on several properties such as taste and texture. They will be informed that they can eat as much or as little as they like in order to rate the food. The amount that the participant consumes will serve as the dependent variable. An interaction between training condition and depletion condition is expected, such that participants who received executive function training will not demonstrate a depletion effect compared to those who did not receive training.

The intervention will be administered in a laboratory setting, in a single session, by a psychologist. The training/placebo tasks and the depletion/no depletion tasks are computerised, and will therefore be administered using a computer. The training/placebo task will take approximately 10 minutes, while the depletion/no depletion task will take 5 minutes.


Details on executive function training task: A stop-signal task that has been modified to include unhealthy food stimuli will be employed to train executive function, specifically inhibitory control. Participants in the training condition will be required to categorise images of unhealthy food and neutral items, and refrain from responding when presented with a signal. These signals will only be paired with unhealthy food stimuli. In this way, participants will learn to associate a stop response with unhealthy food stimuli.

Details of depletion task: Participants will be required to complete a writing task in which they will be asked to compose a paragraph describing a recent event without using words that contain the letters 'a' or 'n'. As words such as these are quite frequent, the task is expected to be quite difficult and result in a depletion effect.
Intervention code [1] 290482 0
Behaviour
Intervention code [2] 290483 0
Treatment: Other
Intervention code [3] 290484 0
Lifestyle
Comparator / control treatment
Participants receiving the placebo training will complete a stop-signal task where the stop-signal is not contingent on the type of stimuli. The association between the stop response and unhealthy food is not expected to develop in this condition.

Participants completing the no-depletion task will receive the same task and instructions as the depletion task, however, instead of being required to construct a paragraph without using words containing the letters 'a' and 'n', participants will be require to compose a paragraph without using words containing the letters 'x' and 'z'. As words containing the letters 'x' and 'z' are no frequent, this task is not expected to cause a depletion effect.

As described above, these tasks will be administered in one session, in a laboratory setting, by a psychologist.
Control group
Placebo

Outcomes
Primary outcome [1] 293442 0
Consumption of unhealthy food.

Participants will be informed that they are completing an unrelated experiment in which they have to rate a new flavour of a particular snack food (e.g. chocolate). Participants will be left alone with a bowl of the snack food and asked to rate this food on several properties such as taste and texture. They will be informed that they can eat as much or as little as they like in order to rate the food. The amount that the participant consumes will serve as the dependent variable.
Timepoint [1] 293442 0
Immediately following intervention-
After participants have completed either training or placebo and depletion or no depletion task, the taste test will be administered. They will be left alone with the bowl of snack food for 10 minutes.
Secondary outcome [1] 311064 0
nil
Timepoint [1] 311064 0
n/a

Eligibility
Key inclusion criteria
Individuals will only be asked to express interest in the study if they describe themselves as motivated to eat healthily but unsuccessful. They will indicate on a 7 point scale how motivated they are to eat healthily, and how (un)successful they perceive themselves to be. If they score above 5 (high motivation/low success) on both items they will be invited to join the study.
Minimum age
18 Years
Maximum age
60 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Dietary allergies or restrictions
Past or present diagnosis of an eating disorder

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)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s

Intervention assignment
Factorial
Other design features
Phase
Type of endpoint/s
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
21/11/2014
Actual
23/04/2015
Date of last participant enrolment
Anticipated
Actual
10/08/2015
Date of last data collection
Anticipated
Actual
Sample size
Target
150
Accrual to date
Final
132
Recruitment in Australia
Recruitment state(s)
WA

Funding & Sponsors
Funding source category [1] 290144 0
University
Name [1] 290144 0
Curtin University
Country [1] 290144 0
Australia
Primary sponsor type
University
Name
Curtin University
Address
Kent St, Bentley
6102 WA
Country
Australia
Secondary sponsor category [1] 288853 0
None
Name [1] 288853 0
Address [1] 288853 0
Country [1] 288853 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 291852 0
Human Research Ethics Committee
Ethics committee address [1] 291852 0
Office of Research and Development
Curtin University
Kent St, Bentley
6102, WA
Ethics committee country [1] 291852 0
Australia
Date submitted for ethics approval [1] 291852 0
Approval date [1] 291852 0
09/09/2014
Ethics approval number [1] 291852 0
HR 173/2014

Summary
Brief summary
Background: Overweight and obesity are major health problems in Australia, with 61% of the population being either overweight or obese. Individuals, low in self-control, consume greater amounts of unhealthy food and are more likely to be overweight. Executive function training, an intervention technique designed to increase self-control and consequently decrease unhealthy food consumption, has demonstrated moderate success. However, researchers employing this technique have not focused on the mechanisms underlying the effect of training.
Objectives: To conduct an executive function training intervention to determine whether training buffers against self-control ‘depletion’ effects and results in less unhealthy eating behaviour.
Methods: Participants will either complete an executive function training paradigm or an inert version of training, followed by a self-control depletion task or a non-depleting task, and finally a taste test.
Expected Findings: Those who receive training will eat less unhealthy food after the depletion task compared to those who did not receive training.
Trial website
Trial related presentations / publications
Public notes
Attachments [1] 218 218 0 0
/AnzctrAttachments/367303-Form_A.pdf
Attachments [2] 220 220 0 0
/AnzctrAttachments/367303-Ethics approval.pdf

Contacts
Principal investigator
Name 52270 0
Dr Vanessa Allom
Address 52270 0
School of Psychology and Speech Pathology
Faculty of Health Sciences
Curtin University
Kent St, Bentley
6102, WA
GPO Box U1987
Country 52270 0
Australia
Phone 52270 0
+61892661399
Fax 52270 0
Email 52270 0
[email protected]
Contact person for public queries
Name 52271 0
Vanessa Allom
Address 52271 0
School of Psychology and Speech Pathology
Faculty of Health Sciences
Curtin University
Kent St, Bentley
6102, WA
GPO Box U1987
Country 52271 0
Australia
Phone 52271 0
+61892661399
Fax 52271 0
Email 52271 0
[email protected]
Contact person for scientific queries
Name 52272 0
Vanessa Allom
Address 52272 0
School of Psychology and Speech Pathology
Faculty of Health Sciences
Curtin University
Kent St, Bentley
6102, WA
GPO Box U1987
Country 52272 0
Australia
Phone 52272 0
+61892661399
Fax 52272 0
Email 52272 0
[email protected]

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