Acute Tryptophan Depletion Effects on the Vertex and Late Positive Potentials to Emotional Faces in Individuals with a Family History of Depression

Background: Depression, which is associated with dysfunctional serotonin (5-HT) activity, may be characterized by impaired emotional information processing. This study assessed the effects of acute tryptophan depletion (TRP–), which transiently lowers CNS 5-HT, on the emotion-sensitive vertex positive potential (VPP) and late positive potential (LPP) event-related potentials (ERPs) and mood in individuals with a family history of depression. The VPP and LPP are thought to index the early and later stages of motivated attentional processing, respectively. Method: Within a double-blind balanced design, ERPs were acquired in 18 individuals with a family history of depression (12 females) after TRP– and TRP+ (balanced) treatment while participants were presented with facial expressions (neutral, as well as sad, joy and surprise at 50 and 100% intensity) and responded to surprised faces. Results: TRP– increased total mood disturbance and maintained depression scores. The VPP and LPP were larger to intense versus mild expressions. Enhanced processing of emotional versus neutral faces, as indexed by the VPP, was primarily evident with TRP–. Speeded and enhanced processing of intensely joyful versus mildly sad faces was found with TRP– (VPP indexed). Compared with TRP+, TRP also increased the VPP to mildly joyful faces. Conclusion: Transient 5-HT decreases in individuals with a family history of depression induce subtle changes in early stages of motivated emotional processing, though not in later ones.