Am J Psychiatry 1997; 154:1153-1155
Copyright © 1997 by American Psychiatric Association
Rapid tryptophan depletion in drug-free depressed patients with seasonal affective disorder
A Neumeister, N Praschak-Rieder, B Hesselmann, O Vitouch, M Rauh, A Barocka and S Kasper
Department of General Psychiatry, Vienna University, Austria.
OBJECTIVE: Brain serotonin systems might be involved in the pathophysiology
of seasonal affective disorder. The authors tested whether tryptophan
depletion alters the mood of depressed patients with seasonal affective
disorder. METHOD: Eleven drug-free depressed patients with seasonal
affective disorder underwent tryptophan depletion in a placebo-controlled,
double-blind crossover study. Tryptophan depletion was induced by a 24-hour
low-tryptophan diet and by ingestion of a tryptophan-free amino acid
beverage. During control testing the diet and the beverage were
supplemented with tryptophan. Behavioral ratings and plasma total and free
tryptophan levels were obtained before the diet started and several times
after administration of the beverages. RESULTS: The diet and the
tryptophan-free amino acid drink reduced plasma total and free tryptophan
levels by 79.0% and 87.5%, respectively. Both levels increased during
control testing. No significant behavioral changes were induced by
tryptophan depletion or control testing. CONCLUSIONS: The failure of
tryptophan depletion to exacerbate the depressive syndrome suggests that
dysfunctional serotonergic activity does not play a primary, direct role in
the pathogenesis of winter depression.
