None listed
Conditions
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.
Interventions
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 th
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.
Sponsors
University of Western Australia
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Educational / counselling / training
Masking
Blinded (masking used)
Eligibility
Sex/Gender
All
Age
18 Years to 65 Years
Healthy volunteers
No
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)
Exclusion criteria
Comorbid bipolar disorder, psychotic disorder, substance misuse disorder, major madical condition, the use of other psychiatric medication, pregnant, breastfeeding.
Outcome results
None listed