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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) 4236 0
Condition category
Condition code
Mental Health 4458 4458 0 0
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] 3957 0
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] 5337 0
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] 5337 0
pre and peak response following disorder specific provocation (5 hours post amino acid mixture ingestion).
Secondary outcome [1] 8970 0
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] 8970 0
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?
No
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
8
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
Recruitment outside Australia
Country [1] 1548 0
United Kingdom
State/province [1] 1548 0

Funding & Sponsors
Funding source category [1] 4420 0
Charities/Societies/Foundations
Name [1] 4420 0
Raine Medical Research Foundation
Country [1] 4420 0
Australia
Primary sponsor type
University
Name
University of Western Australia
Address
35 Stirling Hwy Crawley, Western Australia, 6009
Country
Australia
Secondary sponsor category [1] 3980 0
None
Name [1] 3980 0
Address [1] 3980 0
Country [1] 3980 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 6469 0
University of Western Australia Human Research Ethics Committee
Ethics committee address [1] 6469 0
35 Stirling Hwy Crawley, Western Australia, 6009
Ethics committee country [1] 6469 0
Australia
Date submitted for ethics approval [1] 6469 0
Approval date [1] 6469 0
20/06/2005
Ethics approval number [1] 6469 0
RA/4/1/1193
Ethics committee name [2] 6470 0
South Metropolitan Area Health Service
Ethics committee address [2] 6470 0
Alma Street Fremantle WA 6160
Ethics committee country [2] 6470 0
Australia
Date submitted for ethics approval [2] 6470 0
Approval date [2] 6470 0
21/12/2005
Ethics approval number [2] 6470 0
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 29219 0
Address 29219 0
Country 29219 0
Phone 29219 0
Fax 29219 0
Email 29219 0
Contact person for public queries
Name 12466 0
Dr Sean Hood
Address 12466 0
School of Psychiatry & Clinical Neurosciences (M521)
The University of Western Australia
Queen Elizabeth II Medical Centre
Verdun Street
Nedlands, Western Australia, 6009
Country 12466 0
Australia
Phone 12466 0
+61 8 9346 2393
Fax 12466 0
Email 12466 0
[email protected]
Contact person for scientific queries
Name 3394 0
Dr Sean Hood
Address 3394 0
School of Psychiatry & Clinical Neurosciences (M521)
The University of Western Australia
Queen Elizabeth II Medical Centre
Verdun Street
Nedlands, Western Australia 6009
Country 3394 0
Australia
Phone 3394 0
+61 8 9346 2393
Fax 3394 0
Email 3394 0
[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

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
SourceTitleYear of PublicationDOI
EmbaseEffects of tryptophan depletion on selective serotonin reuptake inhibitor-remitted patients with obsessive compulsive disorder.2017https://dx.doi.org/10.1177/0269881117736916
N.B. These documents automatically identified may not have been verified by the study sponsor.