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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. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Acute tryptophan depletion (ATD) has shown depletion-specific increases in depressed mood and overall depressive symptoms, especially in those with a family history and in remitted patients. However, its effect on a broad range of emotions beyond depressed mood has been inconsistent, and studies have rarely employed a negative mood induction. Method: The present double-blind study administered tryptophan-depleted and taste-matched placebo challenge drinks to individuals with a past diagnosis and family history of depression (i.e. depression-vulnerable subjects) and controls in order to investigate the effect of ATD on positive affect, anxiety, anger and depressed mood following a negative mood induction. Results: Certain aspects of positive affect decreased due to ATD in the depression vulnerables but not in the controls. No differential effects were found on depressed mood and anxiety. Conclusions: A stress-induced blunted hedonic capacity may increase vulnerability to ATD and may be a core emotional abnormality in depression. Additionally, serotonin may have a stronger influence on positive affect than on other depression-related emotions during periods of stress. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: The present study investigated the effects of rapid tryptophan depletion (RTD), and the ensuing reduction of central nervous system levels of serotonin (5-HT), upon reactive aggression in patients with attention deficit/hyperactivity disorder (ADHD). Furthermore, it was asked whether the relation between 5-HT function and behavioural aggression in patients is influenced by their age, the intensity of their attention problems or their comorbid symptoms. Methods: The study employed a double-blind, within-subject crossover design. On day 1, 22 male adolescent patients with ADHD were subjected to RTD and the subsequent reduction of central 5-HT levels. On day 2, they received a tryptophan-balanced amino acid mixture (BAL), which acted as a placebo. On both days, 4.5 h after the intake of the RTD/BAL amino acids, reactive aggressive behaviour was provoked using a competitive reaction time game, which consisted of both high and low provocation conditions. Results: The number of aggressive responses was significantly higher after low provocation during acute tryptophan depletion, in comparison to the placebo. Furthermore, this study provides evidence that neither age nor the intensity of attention symptoms in ADHD patients had an impact on the relation between 5-HT and reactive aggression. Conclusion: This study indicates that in children with ADHD, there is an inverse relationship between 5-HT and aggression. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Previous studies suggest that obsessive-compulsive disorder (OCD) is associated with moderate cognitive deficits. There is also evidence for altered serotonergic transmission in OCD. The aim of this study was to evaluate the impact of rapid plasma tryptophan depletion on cognitive functioning in OCD. Methods: A double-blind crossover study was conducted to explore the effects of tryptophan depletion on cognitive functioning, obsessive or compulsive (OC) symptoms and mood in OCD patients treated with selective serotonin reuptake inhibitors. Results: After 5 h of tryptophan depletion, 6 out of 7 patients reported worsening of mood (placebo condition: 3 patients). No effect was found regarding OC symptoms. There was a small and nonsignificant improvement of nonverbal memory and fluency. Problem solving ability and verbal memory, in contrast, were slightly impaired after tryptophan depletion. The results, however, represented only tendencies without reaching significance. Conclusion: The results suggest that OC symptoms may not depend on the short-time availability of serotonin. As some critical cognitive functions improved following tryptophan depletion, there is no evidence from our study that neuropsychological impairment in OCD can be reduced to a lowered level of serotonin. Future studies are needed to further clarify these findings by use of larger samples. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

This study investigated the relationship between trait hostility and aspects of serotonergic function by assessing the prolactin (PRL) response to acute tryptophan depletion and enhancement in 28 healthy male volunteers. Serum PRL was assessed immediately before, and 4.5 h after, administration of an amino acid drink enhanced with, or depleted of, the 5-HT precursor tryptophan. Trait hostility and ΔPRL (value at 4.5 h minus baseline) correlated negatively following enhancement and positively following depletion, indicating that the higher the hostility the smaller the change in PRL in either direction. This is consistent with previous research reporting an association between aggression and blunted neuroendocrine responses to serotonergic agents. The results indicate the possibility that, in people high on hostility, part of the serotonergic pathway that leads to modulation of PRL release is characterised by a stage with either low capacity relative to input availability or a strong negative feedback component.Copyright © 1999 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]