Tryptophan depletion in patients with Selective Serotonin Reuptake Inhibitor (SSRI)-remitted anxiety disorders

ISRCTN	ISRCTN01523262
DOI	https://doi.org/10.1186/ISRCTN01523262
Secondary identifying numbers	RA/4/1/1193, ACTRN12609000170224

Submission date: 15/04/2005
Registration date: 10/05/2005
Last edited: 12/01/2021

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Mental and Behavioural Disorders

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Plain English summary of protocol

Not provided at time of registration

Contact information

Dr Sean Hood
Scientific

School of Psychiatry and Clinical Neurosciences (M521)
Queen Elizabeth II Medical Centre
Nedlands
Perth
6009
Australia

Phone	+61 (0)8 93462393
Email	sean@cyllene.uwa.edu.au

Study information

Study design	Randomised controlled trial
Primary study design	Interventional
Secondary study design	Randomised controlled trial
Study setting(s)	Not specified
Study type	Not Specified
Scientific title	Tryptophan depletion in patients with Selective Serotonin Reuptake Inhibitor (SSRI)-remitted anxiety disorders
Study objectives	Primary hypotheses: 1. Tryptophan depletion (TD) will cause transient symptom relapse in SSRI-remitted GAD patients, but only when challenged with the 7.5% CO2 provocation paradigm (Study 2) 2. OCD patients well on SSRIs will not relapse spontaneously when undergoing TD but will suffer a significant worsening of anxiety when exposed to a personalised phobic stimulus (Study 1) Secondary hypotheses: 1. TD will have a greater impact upon women than men, according to primary outcome measures 2. Women will experience more nausea on the occasion that they have the tryptophan-restored (control) drink than on the tryptophan-depleted occasion 3. Transient depressive symptoms will be seen in subjects with a past history of depressive illness, despite the absence of a current or recent diagnosis of a depressive disorder
Ethics approval(s)	Not provided at time of registration
Health condition(s) or problem(s) studied	Obsessive-compulsive disorder (OCD); Generalised anxiety disorder (GAD).
Intervention	1. Tryptophan depletion (double-blind crossover) vs tryptophan restored intervention 2. Disorder specific provocation, viz: a. 20 min 7.5% CO2 inhalation or air (GAD) b. Exposure to a known anxiogenic stimulus (OCD)
Intervention type	Other
Primary outcome measure	Study 1: Visual Analogue Scales (VAS), The Spielberger State Anxiety Inventory (STAI), tryptophan levels, c. Profile of Mood States (POMS), Yale-Brown Obsessive Compulsive Scale (Y-BOCS) Study 2: Visual Analogue Scales (VAS), The Spielberger State Anxiety Inventory (STAI), tryptophan levels, c. Profile of Mood States(POMS), Generalised Anxiety Disorder Inventory (GADI)
Secondary outcome measures	Beck Depression Inventory (BDI), Blood pressure/heart rate data, Swedish universities Scales of Personality (SSP).
Overall study start date	01/07/2005
Completion date	31/12/2006

Eligibility

Participant type(s)	Patient
Age group	Adult
Lower age limit	18 Years
Upper age limit	65 Years
Sex	Both
Target number of participants	28
Total final enrolment	12
Key inclusion criteria	Study 1: Primary diagnosis of obsessive-compulsive disorder (OCD), currently remitted with SSRI therapy Study 2: Primary diagnosis of generalised anxiety disorder (GAD), currently remitted with SSRI therapy Aged 18-65 Able and willing to give informed consent prior to participation
Key exclusion criteria	1. No significant co-morbid anxiety disorder or other psychiatric disorder including alcohol or drug dependence 2. No major depressive episode with past 6 months 3. No significant other illness 4. No significant other medication therapy 5. No psychological therapy applied this episode
Date of first enrolment	01/07/2005
Date of final enrolment	31/12/2006

Locations

Countries of recruitment

Australia

Study participating centre

School of Psychiatry and Clinical Neurosciences (M521)

Perth
6009
Australia

Sponsor information

Raine Medical Research Foundation (Australia)
Research organisation

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

Phone	+61 (0)8 93869880
Email	raine@raine.uwa.edu.au
"ROR"	https://ror.org/04agdqh30

Funders

Funder type

Research organisation

Raine Priming Grant 2005-6.

No information available

Results and Publications

Intention to publish date
Individual participant data (IPD) Intention to share	No
IPD sharing plan summary	Not provided at time of registration
Publication and dissemination plan	Not provided at time of registration
IPD sharing plan

Study outputs

Output type	Details	Date created	Date added	Peer reviewed?	Patient-facing?
Results article	results	01/02/2010	12/01/2021	Yes	No

Editorial Notes

12/01/2021: The following changes have been made:
1. Publication reference added.
2. The final enrolment number has been added from the reference.
3. The ANZCTR number has been added.