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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Using transcranial direct current stimulation (tDCS) to improve working memory in schizophrenia and healthy controls: investigating the role of current strength
Scientific title
Using transcranial direct current stimulation (tDCS) to improve working memory in schizophrenia and healthy controls: investigating the role of current strength at three time points post stimulation.
Secondary ID [1] 281405 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Schizophrenia 287650 0
Condition category
Condition code
Mental Health 287983 287983 0 0

Study type
Description of intervention(s) / exposure
Anodal transcranial direct current stimulation (tDCS) at 1mA and 2mA intensity. This will be applied to the left dorsolateral prefrontal cortex for 20 minutes using a neuroConn GBH/Eldith DC Stimulator. tDCS will be delivered during three sessions (1mA tDCS, 2mA tDCS, and sham tDCS) that will be at least 48 hours apart
Intervention code [1] 285893 0
Treatment: Devices
Comparator / control treatment
Sham transcranial direct current stimulation (tDCS). This will involve placing the electrodes in the same position as for active tDCS, however stimulation will be ceased after 30 seconds (so as to generate the same initial sensation and ensure blinding is maintained).
Control group

Primary outcome [1] 288195 0
A statistically significant improvement in performance on a working memory task (i.e. N-Back) following application of tDCS stimulation, both in patients with schizophrenia/ schizoaffective disorder and in healthy controls.
Timepoint [1] 288195 0
Performance will be assessed immediately following stimulation, 20 minutes and 40 minutes post stimulation.
Secondary outcome [1] 299590 0
Timepoint [1] 299590 0

Key inclusion criteria
This study will involve both patients with schizophrenia and healthy controls. As such inclusion and exclusion criteria are defined separately for these groups.

Participants with schizophrenia will be included if they:
- are voluntary and competent to consent
- have a diagnosis of Schizophrenia or Schizoaffective Disorder as confirmed by the Structure Clinical Interview for the Diagnostic and Statistical Manual (DSM) -IV (SCID-IV)

Healthy individuals will be included if they:
- have capacity to consent
- have no personal history of psychiatric illness (lifetime) - based on self report.
Minimum age
18 Years
Maximum age
65 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Patients with schizophrenia will be excluded if they:
- have a a DSM-IV history of substance abuse or dependence in the last 6 months
- have a concomitant major and/or unstable medical or neurologic illness
- are currently taking carbamazepine
- are currently pregnant or lactating
- have metal anywhere in the head, except the mouth (this includes metallic objects such as screws and clips from surgical procedures)

Healthy participants will be excluded if they:
- have an unstable medical condition, neurological disorder or are currently pregnant or lactating
- have metal in the cranium, a pacemaker, cochlear implant medication pump or other electronic device

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
This is a double-blind study. Neither the participant nor the researcher conducting the sessions will know what type of stimulation the participant is receiving during each session. . The stimulation condition will be counterbalanced across participants. A spreadsheet containing the six digit stimulation codes for each session randomised across conditions and participants is prepared by the chief investigator prior to recruitment commencing. Following the screening process and once the participant is enrolled in the study randomization takes place. At this time the Chief Investigator, who will be unblinded, will from this spreadsheet provide a unique six digit code to be entered into the tDCS stimulator, which will determine the stimulation condition and settings, thus allowing the second researcher to remain blinded.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 286166 0
Name [1] 286166 0
Monash University
Address [1] 286166 0
Monash University
Wellington Rd
Clayton VIC 3800
Country [1] 286166 0
Primary sponsor type
Dr Kate Hoy
Level 4, 607 St Kilda Road
Melbourne VIC 3004
Secondary sponsor category [1] 284978 0
Name [1] 284978 0
Address [1] 284978 0
Country [1] 284978 0

Ethics approval
Ethics application status
Ethics committee name [1] 288227 0
Alfred Human Research Ethics Committee
Ethics committee address [1] 288227 0
Ethics Office
Ground Floor, Linay Pavilion
The Alfred
Melbourne VIC 3004
Ethics committee country [1] 288227 0
Date submitted for ethics approval [1] 288227 0
Approval date [1] 288227 0
Ethics approval number [1] 288227 0

Brief summary
Working memory is essential for key cognitive processes including reasoning, language comprehension and learning. Many neurological and psychiatric disorders result in working memory impairments and any technique that may enhance working memory would be very useful. For example cognitive dysfunction is a core feature of schizophrenia. The main areas affected include attention, memory and executive functioning; with working memory in particular frequently affected. These difficulties have been shown to negatively influence patients’ psychosocial functioning. Traditional treatment approaches have resulted in small gains at best. It is therefore essential that novel treatment approaches are explored. Recent research has suggested that brain stimulation, and in particular transcranial Direct Current Stimulation (tDCS), may have a role to play in improving cognition. While tDCS has been shown to improve working memory in a number of conditions, to date there have been no tDCS studies looking at the enhancement of working memory in schizophrenia.
tDCS has been shown to be safe, with very few side effects. It involves the application of a very weak electrical current (1-2mA) using two surface electrodes (anode and cathode) to the head. The use of tDCS on the cortex has been shown to alter the how likely nerve cells are to fire and the effect generally has been shown to last up to 1 hour after stimulation. To date, a number of studies have examined the effect of tDCS on working memory, with some mixed results. While some studies have shown improvements in working memory during a session of tDCS (Boggio et al., 2006), other recent research has found no significant improvement (Marshall et al., 2005). A recent study has shown significantly better performance in a working memory task completed during an application of tDCS to the dorsolateral prefrontal cortex (DLPFC), a part of the brain associated with this type of thinking activity (Fregni et al., 2005). However, despite the breadth of tDCS research being undertaken, many questions remain regarding the most effective stimulation parameters, particularly with respect to optimal current strength (i.e. 1 or 2 mA).
The current study aims investigate this in healthy participants and patients with schizophrenia.
Trial website
Trial related presentations / publications
Hoy KE, Emonson M, Arnold S, Thomson R, Daskalakis ZJ, Fitzgerald PB. Testing the Limits: Investigating the effect of tDCS dose on working memory enhancement in healthy controls. Neuropsychologia, 51; 1777-1784, 2013.

Hoy KE, Arnold S, Emonson M, Daskalakis ZJ, Fitzgerald PB. An investigation into effects of tDCS dose on cognitive performance over time in patients with schizophrenia. Schizophrenia Research. 155, 96–100; 2014.

Hoy KE, Bailey NW, Arnold SL, Fitzgerald PB. The effect of tDCS on gamma activity and working memory in schizophrenia. Psychiatry Research. 228(2), 191-196, 2015
Public notes

Principal investigator
Name 34842 0
A/Prof Kate Hoy
Address 34842 0
MAPrc, Level 4 607 St Kilda Road
Melbourne, VIC 3004
Country 34842 0
Phone 34842 0
+ 61 3 90765034
Fax 34842 0
Email 34842 0
Contact person for public queries
Name 18089 0
Ms Ms. Sara Arnold
Address 18089 0
Level 4, 607 St Kilda Road
Melbourne VIC 3004
Country 18089 0
Phone 18089 0
+61 3 9076 6592
Fax 18089 0
Email 18089 0
Contact person for scientific queries
Name 9017 0
A/Prof Dr Kate Hoy
Address 9017 0
Level 4, 607 St Kilda Road
Melbourne VIC 3004
Country 9017 0
Phone 9017 0
+61 3 9076 5034
Fax 9017 0
Email 9017 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary