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Trial registered on ANZCTR

Registration number

ACTRN12612001112853

Ethics application status

Approved

Date submitted

17/10/2012

Date registered

17/10/2012

Date last updated

2/07/2018

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]

Nil

Universal Trial Number (UTN)

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Schizophrenia

Condition category

Condition code

Mental Health

Schizophrenia

Intervention/exposure

Study type

Interventional

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]

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

Placebo

Outcomes

Primary outcome [1]

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]

Performance will be assessed immediately following stimulation, 20 minutes and 40 minutes post stimulation.

Secondary outcome [1]

Nil

Timepoint [1]

Nil

Eligibility

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

Sex

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

Treatment

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

Crossover

Other design features

Phase

Not Applicable

Type of endpoint/s

Safety/efficacy

Statistical methods / analysis

Recruitment

Recruitment status

Completed

Date of first participant enrolment

Anticipated

29/05/2010

Actual

31/05/2010

Date of last participant enrolment

Anticipated

Actual

1/02/2013

Date of last data collection

Anticipated

Actual

8/02/2013

Sample size

Target

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

VIC

Funding & Sponsors

Funding source category [1]

University

Name [1]

Monash University

Address [1]

Monash University
Wellington Rd
Clayton VIC 3800

Country [1]

Australia

Primary sponsor type

Individual

Name

Dr Kate Hoy

Address

MAPrc,
Level 4, 607 St Kilda Road
Melbourne VIC 3004

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Alfred Human Research Ethics Committee

Ethics committee address [1]

Ethics Office
Ground Floor, Linay Pavilion
The Alfred
Melbourne VIC 3004

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

Approval date [1]

05/05/2010

Ethics approval number [1]

89_10

Summary

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

Contacts

Principal investigator

Name

A/Prof Kate Hoy

Address

MAPrc, Level 4 607 St Kilda Road
Melbourne, VIC 3004

Country

Australia

Phone

+ 61 3 90765034

Fax

[email protected]

Contact person for public queries

Name

Ms. Sara Arnold

Address

MAPrc,
Level 4, 607 St Kilda Road
Melbourne VIC 3004

Country

Australia

Phone

+61 3 9076 6592

Fax

[email protected]

Contact person for scientific queries

Name

Dr Kate Hoy

Address

MAPrc,
Level 4, 607 St Kilda Road
Melbourne VIC 3004

Country

Australia

Phone

+61 3 9076 5034

Fax

[email protected]

No information has been provided regarding IPD availability

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

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