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Effects of rapid tryptophan depletion in patients with seasonal affective disorder in natural summer remission.
Psychol Med 2000; 30(1):79-87PM

Abstract

BACKGROUND

Serotonergic mechanisms have been proposed for the pathophysiology of seasonal affective disorder (SAD) and the therapeutic effect of bright-light treatment. Previously, we showed that SAD patients, in clinical remission with light therapy during the winter, experienced transient depressive relapses after a rapid tryptophan depletion (RTD) technique, which results in decreased brain serotonin levels. The objective of this study was to investigate the effect of RTD in SAD patients who were in natural summer remission.

METHODS

Twelve drug-free patients with SAD by DSM-IV criteria and 10 normal subjects participated in this double-blind, placebo-controlled, crossover study. SAD patients were in natural summer remission for at least 8 weeks. Behavioural ratings and plasma tryptophan levels were obtained before, and 5 h after, ingesting an amino acid (AA) mixture +/- tryptophan. Experimental RTD and control sessions were scheduled 1 week apart.

RESULTS

The RTD session resulted in significant reduction in total and free plasma tryptophan levels compared to the control session. The behavioural data were analysed using repeated measures analysis of variance. This analysis found significant main effects of time (higher scores after AA ingestion) and diagnosis (higher scores in SAD patients), but no main effect of session or significant interaction effects between the three factors. Thus, there were no significant behavioural effects of RTD compared to the sham depletion control session.

CONCLUSIONS

The summer remission experienced by SAD patients is not dependent on plasma tryptophan levels (and presumably brain serotonin function) in the same manner as that of remission after light therapy. These results conflict with those of other laboratories, perhaps because of differences in study samples.

Authors+Show Affiliations

Department of Psychiatry, University of British Columbia, Vancouver, Canada.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

10722178

Citation

Lam, R W., et al. "Effects of Rapid Tryptophan Depletion in Patients With Seasonal Affective Disorder in Natural Summer Remission." Psychological Medicine, vol. 30, no. 1, 2000, pp. 79-87.
Lam RW, Bowering TA, Tam EM, et al. Effects of rapid tryptophan depletion in patients with seasonal affective disorder in natural summer remission. Psychol Med. 2000;30(1):79-87.
Lam, R. W., Bowering, T. A., Tam, E. M., Grewal, A., Yatham, L. N., Shiah, I. S., & Zis, A. P. (2000). Effects of rapid tryptophan depletion in patients with seasonal affective disorder in natural summer remission. Psychological Medicine, 30(1), pp. 79-87.
Lam RW, et al. Effects of Rapid Tryptophan Depletion in Patients With Seasonal Affective Disorder in Natural Summer Remission. Psychol Med. 2000;30(1):79-87. PubMed PMID: 10722178.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of rapid tryptophan depletion in patients with seasonal affective disorder in natural summer remission. AU - Lam,R W, AU - Bowering,T A, AU - Tam,E M, AU - Grewal,A, AU - Yatham,L N, AU - Shiah,I S, AU - Zis,A P, PY - 2000/3/18/pubmed PY - 2000/5/20/medline PY - 2000/3/18/entrez SP - 79 EP - 87 JF - Psychological medicine JO - Psychol Med VL - 30 IS - 1 N2 - BACKGROUND: Serotonergic mechanisms have been proposed for the pathophysiology of seasonal affective disorder (SAD) and the therapeutic effect of bright-light treatment. Previously, we showed that SAD patients, in clinical remission with light therapy during the winter, experienced transient depressive relapses after a rapid tryptophan depletion (RTD) technique, which results in decreased brain serotonin levels. The objective of this study was to investigate the effect of RTD in SAD patients who were in natural summer remission. METHODS: Twelve drug-free patients with SAD by DSM-IV criteria and 10 normal subjects participated in this double-blind, placebo-controlled, crossover study. SAD patients were in natural summer remission for at least 8 weeks. Behavioural ratings and plasma tryptophan levels were obtained before, and 5 h after, ingesting an amino acid (AA) mixture +/- tryptophan. Experimental RTD and control sessions were scheduled 1 week apart. RESULTS: The RTD session resulted in significant reduction in total and free plasma tryptophan levels compared to the control session. The behavioural data were analysed using repeated measures analysis of variance. This analysis found significant main effects of time (higher scores after AA ingestion) and diagnosis (higher scores in SAD patients), but no main effect of session or significant interaction effects between the three factors. Thus, there were no significant behavioural effects of RTD compared to the sham depletion control session. CONCLUSIONS: The summer remission experienced by SAD patients is not dependent on plasma tryptophan levels (and presumably brain serotonin function) in the same manner as that of remission after light therapy. These results conflict with those of other laboratories, perhaps because of differences in study samples. SN - 0033-2917 UR - https://www.unboundmedicine.com/medline/citation/10722178/Effects_of_rapid_tryptophan_depletion_in_patients_with_seasonal_affective_disorder_in_natural_summer_remission_ L2 - http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=10722178.ui DB - PRIME DP - Unbound Medicine ER -