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Negative affect in healthy populations regulates the appraisal of demanding situations, which tunes subsequent effort mobilization and adjustments in cognitive control. In the present study, we hypothesized that dysphoria in depressed individuals similarly modulates this adaptation, possibly through a neural mechanism involving serotonergic regulation. We tested the effect of dysphoria induced by acute tryptophan depletion (ATD) in remitted depressed patients on conflict adaptation in a Simon task. ATD temporarily lowers the availability of the serotonin precursor L-Tryptophan and is known to increase depressive symptoms in approximately half of remitted depressed participants. We found that depressive symptoms induced by ATD were associated with increased conflict adaptation. Our finding extends recent observations implying an important role of affect in regulating conflict-driven cognitive control. [ABSTRACT FROM AUTHOR]

Abstract: Acute tryptophan depletion (ATD) in currently depressed patients has no immediate effect on symptoms, but leads to transient symptom improvement or worsening the next day. In view of recent findings concerning the cognitive effects of serotonin manipulations, we used ATD in fourteen depressed patients to investigate whether cognitive effects following ATD predict symptom changes. We found that symptom improvement 24h after ATD was associated with an improved recall of positive words and with less attentional bias and recall of negative words, 5h after ATD. These results indicate that serotonergic alterations affect emotional processing which may subsequently lead to symptom changes. [Copyright &y& Elsevier]

Background: Acute tryptophan depletion (ATD) induces depressive symptoms in remitted depressed patients treated with serotonergic medications, but not in patients treated with noradrenergic medications or electroconvulsive therapy. A recent study suggests that cognitive therapy (CT) protects against the effects of ATD, but the evidence is questionable. The present study compared the effect of ATD in patients who were treated with antidepressant medication and CT (n = 17) versus antidepressant medication alone (n = 23) during their latest episode. Methods: Forty remitted depressed patients underwent high-dose and low-dose ATD in a randomized double-blind crossover design. Results: There were no differences in response to ATD between treatment groups. This applied to groups defined by lifetime and by recent CT experience. Conclusions: Cognitive therapy does not protect against the effects of rapidly lowered plasma tryptophan levels in remitted depressed patients who are also treated with antidepressant medication. [Copyright &y& Elsevier]