Efficacy of light versus tryptophan therapy in seasonal affective disorder.
BACKGROUND
Although light therapy has become the accepted treatment for patients suffering from seasonal affective disorder (SAD, winter depression), almost 40% of these patients do not respond, and require an alternative treatment.


METHODS
The therapeutic effects of light versus tryptophan on SAD were studied in a repeated measures design in 13 SAD patients (11 women, 2 men). Light therapy for 2 weeks or tryptophan for 4 weeks was given, separated by a one week washout period. All were assessed with the modified Hamilton Depression Rating scale (SIGH-SAD) at the beginning and end of each treatment.


RESULTS
Four (31%) of the patients did not respond to either therapy. Four tryptophan-resistant patients responded to light therapy, while one light therapy-resistant patient responded to tryptophan. Relapse occurred rapidly after stopping light therapy but not after stopping tryptophan therapy.


CONCLUSIONS
There were significant therapeutic effects of both light (p = 0.012) and tryptophan (p = 0.014) on SAD, which were not significantly different from each other. There may be a time difference between the residual pharmacokinetic effects after stopping therapy.


CONCLUSIONS
The groups studied were small. This was an open study.


CONCLUSIONS
Tryptophan was equally effective to light therapy in treating SAD, but relapse after withdrawal of tryptophan probably occurs more slowly.
Department of Psychiatry, McGill University, Royal Victoria Hospital, Montreal, Quebec, Canada.
A M
AM
Ghadirian
B E
BE
Murphy
M J
MJ
Gendron
D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D010789:Phototherapy; D016574:Seasonal Affective Disorder / Q000188:drug therapy / Q000628:therapy*; D014364:Tryptophan / Q000627:therapeutic use*
D000928:Antidepressive Agents; D014364:Tryptophan