L-tryptophan augmentation of light therapy in patients with seasonal affective disorder.
OBJECTIVE
Up to one-third of patients with seasonal affective disorder (SAD) do not have a full response to light therapy. Given the evidence for serotonergic dysregulation in SAD, we examined the possible role of l-tryptophan as an augmentation strategy for nonresponders and partial responders to light therapy.


METHODS
Eligible drug-free patients meeting DSM-IV criteria for SAD were treated for 2 weeks using a standard morning light therapy regimen (10,000 lux cool-white fluorescent light 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, SAD version (SIGH-SAD) and the Clinical Global Impression (CGI) scale.


RESULTS
Sixteen patients began the l-tryptophan augmentation phase. Two patients discontinued medications within 3 days because of side effects. In the 14 patients completing treatment, the addition of l-tryptophan resulted in significant reduction of mean depression scores. Nine of 14 patients (64%) showed very good clinical responses to combined treatment and minimal side effects.


CONCLUSIONS
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 bright ligh therapy. Further placebo-controlled studies are warranted to demonstrate efficacy.
Lam
R W
RW
Department of Psychiatry, University of British Columbia, Vancouver. rlam@unixg.ubc.ca
Levitan
R D
RD
Tam
E M
EM
Yatham
L N
LN
Lamoureux
S
S
Zis
A P
AP
D000328:Adult; D003131:Combined Modality Therapy; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010555:Personality Inventory; D010789:Phototherapy; D016574:Seasonal Affective Disorder / Q000175:diagnosis / Q000523:psychology / Q000628:therapy*; D016896:Treatment Outcome; D014364:Tryptophan / Q000008:administration & dosage*
D014364:Tryptophan