Tryptophan depletion causes a rapid lowering of mood in normal males

✍ Scribed by Simon N. Young; Scott E. Smith; Robert O. Pihl; Frank R. Ervin

• Book ID: 104771468
• Publisher: Springer
• Year: 1985
• Tongue: English
• Weight: 661 KB
• Volume: 87
• Category: Article
• ISSN: 0033-3158
• DOI: 10.1007/bf00431803

✦ Synopsis

Normal male human subjects ingested amino acid mixtures which were tryptophan-free, balanced or contained excess tryptophan. The tryptophan-free mixture causes a marked depletion of plasma tryptophan by 5 h. At this time the subjects in the tryptophan-free group had significantly elevated scores on the depression scale of the Multiple Affect Adjective Checklist. The tryptophan-free group also performed worse than the other two groups in a proofreading task carried out while listening to a tape with themes of hopelessness and helplessness (dysphoric distractor). Cognitive theories of depression predict greater distractability of depressed individuals by dysphoric themes. Thus, both measures indicate a rapid mood lowering effect of tryptophan depletion in normal males. This effect is probably mediated by a lowering of brain 5-hydroxytryptamine. Although the mood-lowering effect was not as great as that seen in depressed patients, our results suggest that low brain 5HT might be one factor precipitating depression in some patients.