ANZCTR - Registration

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Trial registered on ANZCTR

Registration number

ACTRN12609000170224

Ethics application status

Approved

Date submitted

28/01/2009

Date registered

8/04/2009

Date last updated

8/04/2009

Type of registration

Retrospectively registered

Titles & IDs

Public title

Tryptophan depletion in patients with selective serotonin reuptake inhibitor-remitted generalised anxiety disorder or obsessive compulsive disorder.

Scientific title

The effect of acute tryptophan depletion vs. sham depletion on disorder specific symptoms in people with selective serotonin reuptake inhibitor-remitted generalised anxiety disorder and obsessive compulsive disorder.

Universal Trial Number (UTN)

Trial acronym

Linked study record

Health condition

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

Obsessive compulsive disorder (OCD)

Condition category

Condition code

Mental Health

Anxiety

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

Acute tryptophan depletion through the ingestion of a amino acid mixture without triptophan (100g in 250 mL), which stimulates the liver to produce proteins and leads to competition to cross the blood-brain barrier. This mixture is administered twice: in the morning of the test day (without tryptophan) and in the morning of the control day (with tryptophan), both at 9.30 a.m. The mixture was orally administered.
Its effects are rapidly reversed with reinstatement of the normal alimentation so the week between test and control procedures functions as wash-out period.

Intervention code [1]

Other interventions

Comparator / control treatment

Amino acid mixture (250 mL) with L-alanine (5.5g); L-arginine (4.9g); L-cysteine HCl H2O (3.91g); Glycine (3.2g); L-histidine (3.2g); L-isoleucine (8.0g); L-leucine (13.5g); L-lysine HCL (11.0g); L-methionine (3.0g); L-phenylalanine (5.7g); L-proline (12.2g); L-serine (6.9g); L-threonine (6.5g); L-tyrosine (6.9g); L-valine (8.9g); [total: 100g]. The same mixture as applied in the intervention day [100g in 250 mL] plus L-tryptophan 2.3g function as placebo as it does not leads to depletion. Both mixtures are administered per mouth in the morning of the test day (100g) and in the morning of the placebo day (100g + 2.3g of tryptophan). Both mixtures are administered only once a day at 9.30 a.m.

Control group

Placebo

Outcomes

Primary outcome [1]

Generalised anxiety disorder specific symptoms or obsessive compulsive disorder specific symptoms, measured using the Visual Analogue Scale items:
Generalised anxiety disorder (GAD) - "worried" and "anxious"
Obsessive compulsive disorder (OCD) - "interfering" and "anxious"

Timepoint [1]

pre and peak response following disorder specific provocation (5 hours post amino acid mixture ingestion).

Secondary outcome [1]

Generalised anxiety disorder specific symptoms or obsessive compulsive disorder specific symptoms. For GAD - Spielberger State Anxiety Inventory and for
OCD - Yale Brown Obsessive Compulsive Scale (YBOCS)

Timepoint [1]

pre and peak response following disorder specific provocation (5 hours post amino acid mixture ingestion):

Eligibility

Key inclusion criteria

Generalised anxiety disorder or obsessive compulsive disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria; good response to a selective serotonin reuptake inhibitors (clinical dose ajusted)

Minimum age

18 Years

Maximum age

65 Years

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

Comorbid bipolar disorder, psychotic disorder, substance misuse disorder, major madical condition, the use of other psychiatric medication, pregnant, breastfeeding.

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)

All participants underwent both tryptophan depletion and sham depletion conditions. Participants were assigned to a pre-determined depletion order in order of recruitment using numbered containers (allocation was concealed).

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

Tryptophan/sham depletion order was randomly determined in blocks using a random number generator (www.random.org)

Masking / blinding

Blinded (masking used)

Who is / are masked / blinded?

Intervention assignment

Crossover

Other design features

Phase

Not Applicable

Type of endpoint/s

Efficacy

Statistical methods / analysis

Recruitment

Recruitment status

Completed

Date of first participant enrolment

Anticipated

1/06/2003

Actual

Date of last participant enrolment

Anticipated

Actual

Date of last data collection

Anticipated

Actual

Sample size

Target

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

Recruitment outside Australia

Country [1]

United Kingdom

State/province [1]

Funding & Sponsors

Funding source category [1]

Charities/Societies/Foundations

Name [1]

Raine Medical Research Foundation

Address [1]

Suite 24, 95 Monash Avenue
Hollywood Specialist Centre
Nedlands, Western Australia, 6009

Country [1]

Australia

Primary sponsor type

University

Name

University of Western Australia

Address

35 Stirling Hwy Crawley, Western Australia, 6009

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

University of Western Australia Human Research Ethics Committee

Ethics committee address [1]

35 Stirling Hwy Crawley, Western Australia, 6009

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

Approval date [1]

20/06/2005

Ethics approval number [1]

RA/4/1/1193

Ethics committee name [2]

South Metropolitan Area Health Service

Ethics committee address [2]

Alma Street Fremantle WA 6160

Ethics committee country [2]

Australia

Date submitted for ethics approval [2]

Approval date [2]

21/12/2005

Ethics approval number [2]

05/451

Summary

Brief summary

Antidepressant medications such as selective serotonin reuptake inhibitors (SSRIs - which increase levels of the neurotransmitter serotonin) are now the main treatments of anxiety disorders as well as depression. We have recently demonstrated that the dietary procedure of tryptophan depletion (TD) reverses the anti-anxiety actions of the SSRIs in both panic disorder and social anxiety disorder. 

We now wish to examine the effects of decreasing serotonin in patients with two other anxiety disorders (generalised anxiety disorder and obsessive-compulsive disorder) after SSRI treatment. These studies should help tease out the differences (and similarities) between several major anxiety disorders with respect to serotonergic function, and provide clinically important prognostic information.  We expected that participants will report greater levels of anxiety following a disorder specific challenge when depleted of tryptophan.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Address

Country

Phone

Fax

Contact person for public queries

Name

Dr Sean Hood

Address

School of Psychiatry & Clinical Neurosciences (M521)
The University of Western Australia
Queen Elizabeth II Medical Centre
Verdun Street
Nedlands, Western Australia, 6009

Country

Australia

Phone

+61 8 9346 2393

Fax

sean.hood@uwa.edu.au

Contact person for scientific queries

Name

Dr Sean Hood

Address

School of Psychiatry & Clinical Neurosciences (M521)
The University of Western Australia
Queen Elizabeth II Medical Centre
Verdun Street
Nedlands, Western Australia 6009

Country

Australia

Phone

+61 8 9346 2393

Fax

sean.hood@uwa.edu.au

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

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	Effects of tryptophan depletion on selective serotonin reuptake inhibitor-remitted patients with obsessive compulsive disorder.	2017	https://dx.doi.org/10.1177/0269881117736916

N.B. These documents automatically identified may not have been verified by the study sponsor.

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Documents added manually

Documents added automatically