Lack of effects on core obsessive-compulsive symptoms of tryptophan depletion during symptom provocation in remitted obsessive-compulsive disorder patients.
BACKGROUND
Pharmacological evidence support that enhancement of serotonin (5-HT) neurotransmission is critical for treatment efficacy in obsessive-compulsive disorder (OCD). Surprisingly, acute tryptophan depletion (ATD), a procedure known to reduce 5-HT neurotransmission, carried out in remitted OCD patients on selective serotonin reuptake inhibitors (SSRIs) failed to worsen obsessive-compulsive (OC) symptoms. We hypothesized that the putative symptom exacerbation resulting from ATD would only be observed during symptom provocation but not at rest.


METHODS
Double-blind placebo-controlled ATD study conducted in 16 OCD patients with stable improvement under either SSRI (n = 8) or specialized cognitive behavior therapy alone (n = 8), coupled with gradual symptom provocation, performed 5 hours after drink ingestion.


RESULTS
Acute tryptophan depletion markedly reduced total and free plasma tryptophan levels but did not significantly increase obsessions or compulsions at rest or following symptom provocation. However, subjective distress in response to triggering situations was significantly higher during ATD; significant mood lowering was also present during ATD.


CONCLUSIONS
These results are consistent with the view that relapses in OC core symptoms in remitted OCD patients may not depend solely on short-term changes in presynaptic 5-HT availability. In contrast to its apparent lack of effect on core OC symptoms, ATD affected the patient's mood and distress level resulting from provocation.
Berney
Alexandre
A
Neurobiological Psychiatry Unit, Department of Psychiatry, McGill University, Montreal, Canada.
Sookman
Debbie
D
Leyton
Marco
M
Young
Simon N
SN
Benkelfat
Chawki
C
D000328:Adult; D000704:Analysis of Variance; D015928:Cognitive Behavioral Therapy / Q000379:methods*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D009771:Obsessive-Compulsive Disorder / Q000628:therapy*; D011569:Psychiatric Status Rating Scales; D055502:Secondary Prevention; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use*; D016896:Treatment Outcome; D014364:Tryptophan / Q000172:deficiency* / Q000378:metabolism
D017367:Selective Serotonin Reuptake Inhibitors; D014364:Tryptophan