L-TRYPTOPHAN AUGMENTATION OF LIGHT THERAPY IN PATIENTS WITH SEASONAL AFFECTIVE-DISORDER

Objective: Up to one-third of patients with seasonal affective disorde r (SAD) do not have full response to light therapy. Given the evidence for serotonergic dysregulation in SAD, we examined the possible role of I-tryptophan as an augmentation strategy for nonresponders and part ial responders to light therapy.Method: Eligible drug-free patients me eting DSM-IV criteria for SAD were treated for 2 weeks using a standar d morning light therapy regimen (10 000 lux cool-white fluorescent lig ht for 30 minutes). Partial and nonresponders were treated for 2 weeks with open-label l-tryptophan (1 g 3 times daily) while light therapy was continued. Ratings at baseline and follow-up included the 29-item Structured Interview Guide for the Hamilton Depression Rating Scale, S AD version (SIGH-SAD) and the Clinical Global Impression (CGI) scale. Results: Sixteen patients began the I-tryptophan augmentation phase. T wo patients discontinued medications within 3 days because of side eff ects. In the 14 patients completing treatment, the addition of l-trypt ophan resulted in significant reduction of mean depression scores. Nin e of 14 patients (64%) showed very good clinical responses to combined treatment and minimal side effects. Conclusion: This open-label study suggests that l-tryptophan may be an effective augmentation strategy for those patients with SAD who show limited or poor response to brigh t light therapy. Further placebo-controlled studies are warranted to d emonstrate efficacy.