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Trial registered on ANZCTR


Registration number
ACTRN12613000488707
Ethics application status
Not yet submitted
Date submitted
26/04/2013
Date registered
1/05/2013
Date last updated
22/06/2022
Date data sharing statement initially provided
22/06/2022
Type of registration
Prospectively registered

Titles & IDs
Public title
Examining decision-making using transcranial direct current stimulation
Scientific title
In healthy participants with no history of mental illness, how does transcranial direct current stimulation to the dorsolateral prefrontal cortex affect playing a risky gamble or accepting an unfair monetary distribution?
Secondary ID [1] 282336 0
Nil
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Decision-making processes in healthy volunteers 288884 0
Condition category
Condition code
Mental Health 289227 289227 0 0
Studies of normal psychology, cognitive function and behaviour

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Eldith tDCS stimulator device (DC Stimulator Plus);


Participants will be assigned to one of two arms (each participant will undergo two sessions in total).

For both arms, Session 2 will be scheduled at least 3 days after Session 1.

Arm 1:
Session 1: 20 minutes of transcranial Direct Current Stimulation (tDCS) at 2mA: anodal stimulation to left dorsolateral prefrontal cortex (DLPFC) (electrode placed at F3, based on the international 10-20 system) and cathodal stimulation to right DLPFC (electrode placed at F4).

Session 2: 20 minutes of sham (fake) tDCS (30 seconds of 2 mA tDCS, then current is switched off) to left DLPFC and right DLPFC.


Arm 2:
Session 1: 20 minutes of tDCS at 2mA: anodal stimulation to right DLPFC and cathodal stimulation to left DLPFC

Session 2: 20 minutes of sham (fake) tDCS
Intervention code [1] 286998 0
Behaviour
Intervention code [2] 286999 0
Treatment: Devices
Comparator / control treatment
Control treatment is sham (fake) tDCS (30 seconds of 2 mA tDCS, then current is switched off) to left DLPFC and right DLPFC.
Control group
Placebo

Outcomes
Primary outcome [1] 289383 0
Difference in the proportion of risky gamble choices made on a gambling task between active tDCS and sham tDCS

The gambling task is a simplified version of slot-machines or "pokies". On each trial participants will be given a number of betting options and asked to place a bet. Larger bets associated with larger wins.

Risky gambling choices is defined as the proportion of trials in which participants decide the place the larger bet over the smaller bet.
Timepoint [1] 289383 0
Session 1 and Session 2 (Session 2 will occur at least 3 days after Session 1)

Task performance will be assessed during each session immediately following tDCS treatment.
Primary outcome [2] 289384 0
Difference in the proportion of unfair offers accepted (in Ultimatum Game experimental task) between active tDCS and sham tDCS
Timepoint [2] 289384 0
Session 1 and Session 2 (Session 2 will occur at least 3 days after Session 1)

Task performance will be assessed during each session during tDCS treatment.
Secondary outcome [1] 302386 0
Anhedonia score (as measured by Principal Components Analysis score of Chapman Physical Anhedonia Scale, Chapman Social Anhedonia Scale, Snaith-Hamilton Pleasure Scale, Temporal Experience of Pleasure Scale, Carver and White BIS/BAS scale)
Timepoint [1] 302386 0
Session 2

Outcome will be assessed prior to treatment session

Eligibility
Key inclusion criteria
No history of neurological or psychiatric illness;
Not taking any psychoactive medications;
Able to provide informed consent
Minimum age
18 Years
Maximum age
65 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Presence of metal anywhere in the head (except the mouth);
Have had a prior serious head injury, neurological condition, or other serious medical condition;
Are pregnant.

Study design
Purpose of the study
Educational / counselling / training
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation is not concealed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Randomization to either arm 1 or arm 2 will occur via the generation of a single computer number sequence. Participants will be randomised prior to the commencement of the first session
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s

Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Separate logistic regression will be used to analyse the behavioural data from the experimental tasks with choice behaviour (e.g. High/Low risk choice on the Gambling Task; Yes/No choice on the Ultimatum Game) as the dependent variable. The gamble risk level (for gambling task), fairness level (for ultimatum game task), anhedonia status, and tDCS condition will be used as independent variables.

Electrophysiological data (i.e. Event-Related Potentials) from the Gambling Task only will be analysed using linear regression. ERP amplitude will be the dependent variable, while the independent variables will be gamble risk level, anhedonia status and tDCS treatment condition.

Separate linear regressions will be used to analyse the trial RT data (i.e. time to make decision on each trial), with RT on each trial as the dependent variable, while the independent variables will be gamble risk level, fairness level, anhedonia status and tDCS treatment condition.


Fecteau et al.(2007) conducted a tDCS experiment (participants were healthy college students) with a gambling task. On the key analyses, right anodal/left cathodal vs sham, they observed an OR = 2.5 (95% CI = 1.8-3.3); this can be crudely converted an effect size by dividing ln(OR) by 1.81 (Chinn, 2000), which gives a rough effect size of 0.51; For anodal right/cathodal left vs anodal left/cathodal right, OR = 2.8, which converts to a rough effect size of 0.57. Based on G*Power (for an average effect size of 0.54), the required sample (80% power), for a one-tailed t-test is 24, which is the proposed sample for this study . As we expect anhedonia to amplify the effect size, the above calculation can be considered conservative.

Recruitment
Recruitment status
Withdrawn
Reason for early stopping/withdrawal
Lack of funding/staff/facilities
Date of first participant enrolment
Anticipated
1/06/2013
Actual
Date of last participant enrolment
Anticipated
1/06/2014
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
24
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
VIC
Recruitment hospital [1] 940 0
The Alfred - Prahran
Recruitment postcode(s) [1] 6796 0
3004 - Melbourne

Funding & Sponsors
Funding source category [1] 287161 0
University
Name [1] 287161 0
Funding will be obtained from internal research funds at the Monash Alfred Psychiatry Research Centre
Country [1] 287161 0
Australia
Primary sponsor type
Individual
Name
Professor Paul Fitzgerald
Address
Monash Alfred Psychiatry Research Centre
Level 4, 607 St Kilda Road
Melbourne, VIC 3004, Australia
Country
Australia
Secondary sponsor category [1] 285929 0
None
Name [1] 285929 0
Address [1] 285929 0
Country [1] 285929 0

Ethics approval
Ethics application status
Not yet submitted
Ethics committee name [1] 289158 0
The Alfred Research and Ethics Unit
Ethics committee address [1] 289158 0
The Alfred Hospital, 55 Commercial Road,
Melbourne, VIC 3004
Ethics committee country [1] 289158 0
Australia
Date submitted for ethics approval [1] 289158 0
01/05/2013
Approval date [1] 289158 0
Ethics approval number [1] 289158 0
197/13

Summary
Brief summary
One of the main symptoms of Major Depression is Anhedonia, or a reduced ability to experience pleasure. Anhedonia can reduce one’s motivation to engage in pleasurable activities as well reducing the sense of enjoyment they experience from activities that would typically give them pleasure. As such, it is likely that anhedonia can influence our day-to-day decision-making choices as well.

Prior research has shown that transcranial direct current stimulation (tDCS; a research tool that involves applying low-voltage electrical stimulation to electrodes placed on the scalp) can alter cognitive processing and decision-making in humans. The goal of the present study is to investigate how tDCS to part of the brain known as the dorsolateral prefrontal cortex (DLPFC) can influence economic and social decision-making behaviour in individuals with anhedonia.

By comparing the effects of tDCS on healthy people with varying levels of anhedonia, we hope to better understand the role of the DLPFC in decision-making, and how this is modulate by anhedonic symptoms. The use of electroencephalography (EEG; a research tool that involves recording brain waves from electrodes placed on the scalp), in this study may help us gain a better understanding of the neurological basis of decision-making, and how this is affected by anhedonia.

The hypotheses of the study are that participants receiving tDCS treatment designed to simultaneously increase activity on the right side of their brain and decrease activity on the left side of their brain will (compared to participants receiving tDCS treatment designed to simultaneously decrease activity on the right side of their brain and increase acitivitry on the left side of their brain), be more willing to accept unfair offers to distribute a sum of money and less willing to place a risky bet when playing a gambling game. We also hypothesize that variations in participants' anhedonia levels will affect their behaviour in these tasks; individuals with higher anhedonia levels are hypothesised to show increased acceptance of unfair offers and a decreased willingness to play a risky bet.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 39290 0
Prof Paul Fitzgerald
Address 39290 0
Monash Alfred Psychiatry Research Centre
Level 4, 607 St Kilda Road
Melbourne, VIC 3004, Australia
Country 39290 0
Australia
Phone 39290 0
+61 3 9076 6552
Fax 39290 0
61 3 9276 6588
Email 39290 0
[email protected]
Contact person for public queries
Name 39291 0
Phillip Hall
Address 39291 0
Monash Alfred Psychiatry Research Centre
Level 4, 607 St Kilda Road
Melbourne, VIC 3004, Australia
Country 39291 0
Australia
Phone 39291 0
+61 3 9076 6564
Fax 39291 0
+61 3 9276 6588
Email 39291 0
[email protected]
Contact person for scientific queries
Name 39292 0
Paul Fitzgerald
Address 39292 0
Monash Alfred Psychiatry Research Centre
Level 4, 607 St Kilda Road
Melbourne, VIC 3004, Australia
Country 39292 0
Australia
Phone 39292 0
+61 3 9076 6552
Fax 39292 0
+61 3 9276 6588
Email 39292 0
[email protected]

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


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.