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Letters to the Editor
February 2001

The Mood-Lowering Effect of Tryptophan Depletion: Possible Explanation for Discrepant Findings—Reply

Arch Gen Psychiatry. 2001;58(2):201-202. doi:

In reply

Like many investigators, we have wondered why some but not all euthymic depressed patients treated with SSRIs or monoamine oxidase inhibitors (MAOIs) suffer a clinical relapse following rapid tryptophan depletion (RTD). Many clinical and behavioral measures vary widely between psychiatric patients and healthy volunteers with RTD, although plasma tryptophan reductions tend to be consistent and robust in both groups. Numerous attempts to correlate changes in plasma tryptophan scores with changes in depression scores or other measures have often failed to indicate a significant relationship.1-10