A placebo-controlled clinical trial of L-tryptophan in premenstrual dysphoria

Background: Antidepressant drugs, including specific serotonin reuptake inh ibitors, have been shown to be beneficial in the treatment of premenstrual dysphoric disorder The present study tests the efficacy of L-tryptophan, wh ich acts specifically on serotonergic neurons, in this disorder. Methods: In a randomized controlled clinical trial, 37 patients with premen strual dysphoric disorder were treated with L-tryptophan 6 g per day, and 3 4 were given placebo. The treatments were administered under double-blind c onditions for 17 days, from the rime of ovulation to the third day of menst ruation, during three consecutive menstrual cycles. Results: The Visual Analogue Scales (VAS) revealed a significant (p = .004) therapeutic effect of L-tryptophan relative to placebo for the cluster of mood symptoms comprising the items of dysphoria, moon swings, tension, and irritability. The magnitude of the reduction from baseline in maximum lutea l phase VAS-mood scores was 34.5% with L-tryptophan compared to 10.4% with placebo. Conclusions: These results suggest that increasing serotonin synthesis duri ng the late luteal phase of the menstrual cycle has a beneficial effect in patients with premenstrual dysphoric disorder Biol Psychiatry 1999;45: 313- 320 (C) 1999 Society of Biological Psychiatry.