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Effects of tryptophan depletion vs catecholamine depletion in patients with seasonal affective disorder in remission with light therapy.
Arch Gen Psychiatry 1998; 55(6):524-30AG

Abstract

BACKGROUND

Although hypotheses about the therapeutic mechanism of action of light therapy have focused on serotonergic mechanisms, the potential role, if any, of catecholaminergic pathways has not been fully explored.

METHODS

Sixteen patients with seasonal affective disorder who had responded to a standard regimen of daily 10000-lux light therapy were enrolled in a double-blind, placebo-controlled, randomized crossover study. We compared the effects of tryptophan depletion with catecholamine depletion and sham depletion. Ingestion of a tryptophan-free amino acid beverage plus amino acid capsules was used to deplete tryptophan. Administration of the tyrosine hydroxylase inhibitor alpha-methyl-paratyrosine was used to deplete catecholamines. Diphenhydramine hydrochloride was used as an active placebo during sham depletion. The effects of these interventions were evaluated with measures of depression, plasma tryptophan levels, and plasma catecholamine metabolites.

RESULTS

Tryptophan depletion significantly decreased plasma total and free tryptophan levels. Catecholamine depletion significantly decreased plasma 3-methoxy-4-hydroxyphenylethyleneglycol and homovanillic acid levels. Both tryptophan depletion and catecholamine depletion, compared with sham depletion, induced a robust increase (P<.001, repeated-measures analysis of variance) in depressive symptoms as measured with the Hamilton Depression Rating Scale, Seasonal Affective Disorder Version.

CONCLUSIONS

The beneficial effects of light therapy in the treatment of seasonal affective disorder are reversed by both tryptophan depletion and catecholamine depletion. These findings confirm previous work showing that serotonin plays an important role in the mechanism of action of light therapy and provide new evidence that brain catecholaminergic systems may also be involved.

Authors+Show Affiliations

National Institute of Mental Health, Clinical Psychobiology Branch, Bethesda, MD, USA. alexander.neumeister@akh-wien.ac.atNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

9633671

Citation

Neumeister, A, et al. "Effects of Tryptophan Depletion Vs Catecholamine Depletion in Patients With Seasonal Affective Disorder in Remission With Light Therapy." Archives of General Psychiatry, vol. 55, no. 6, 1998, pp. 524-30.
Neumeister A, Turner EH, Matthews JR, et al. Effects of tryptophan depletion vs catecholamine depletion in patients with seasonal affective disorder in remission with light therapy. Arch Gen Psychiatry. 1998;55(6):524-30.
Neumeister, A., Turner, E. H., Matthews, J. R., Postolache, T. T., Barnett, R. L., Rauh, M., ... Rosenthal, N. E. (1998). Effects of tryptophan depletion vs catecholamine depletion in patients with seasonal affective disorder in remission with light therapy. Archives of General Psychiatry, 55(6), pp. 524-30.
Neumeister A, et al. Effects of Tryptophan Depletion Vs Catecholamine Depletion in Patients With Seasonal Affective Disorder in Remission With Light Therapy. Arch Gen Psychiatry. 1998;55(6):524-30. PubMed PMID: 9633671.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of tryptophan depletion vs catecholamine depletion in patients with seasonal affective disorder in remission with light therapy. AU - Neumeister,A, AU - Turner,E H, AU - Matthews,J R, AU - Postolache,T T, AU - Barnett,R L, AU - Rauh,M, AU - Vetticad,R G, AU - Kasper,S, AU - Rosenthal,N E, PY - 1998/6/20/pubmed PY - 1998/6/20/medline PY - 1998/6/20/entrez SP - 524 EP - 30 JF - Archives of general psychiatry JO - Arch. Gen. Psychiatry VL - 55 IS - 6 N2 - BACKGROUND: Although hypotheses about the therapeutic mechanism of action of light therapy have focused on serotonergic mechanisms, the potential role, if any, of catecholaminergic pathways has not been fully explored. METHODS: Sixteen patients with seasonal affective disorder who had responded to a standard regimen of daily 10000-lux light therapy were enrolled in a double-blind, placebo-controlled, randomized crossover study. We compared the effects of tryptophan depletion with catecholamine depletion and sham depletion. Ingestion of a tryptophan-free amino acid beverage plus amino acid capsules was used to deplete tryptophan. Administration of the tyrosine hydroxylase inhibitor alpha-methyl-paratyrosine was used to deplete catecholamines. Diphenhydramine hydrochloride was used as an active placebo during sham depletion. The effects of these interventions were evaluated with measures of depression, plasma tryptophan levels, and plasma catecholamine metabolites. RESULTS: Tryptophan depletion significantly decreased plasma total and free tryptophan levels. Catecholamine depletion significantly decreased plasma 3-methoxy-4-hydroxyphenylethyleneglycol and homovanillic acid levels. Both tryptophan depletion and catecholamine depletion, compared with sham depletion, induced a robust increase (P<.001, repeated-measures analysis of variance) in depressive symptoms as measured with the Hamilton Depression Rating Scale, Seasonal Affective Disorder Version. CONCLUSIONS: The beneficial effects of light therapy in the treatment of seasonal affective disorder are reversed by both tryptophan depletion and catecholamine depletion. These findings confirm previous work showing that serotonin plays an important role in the mechanism of action of light therapy and provide new evidence that brain catecholaminergic systems may also be involved. SN - 0003-990X UR - https://www.unboundmedicine.com/medline/citation/9633671/Effects_of_tryptophan_depletion_vs_catecholamine_depletion_in_patients_with_seasonal_affective_disorder_in_remission_with_light_therapy_ L2 - http://ovidsp.ovid.com/ovidweb.cgi?T=JS&amp;PAGE=linkout&amp;SEARCH=9633671.ui DB - PRIME DP - Unbound Medicine ER -