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Objective Animal experiments and studies in adults have shown that the neurotransmitter serotonin (5- HT) plays an important role in learning and memory processes. However, data on this relationship in young persons are scarce, and neurodietary research in this age group is limited compared with the extensive literature on adults. Here, we aimed to explore the effects of a diminished central nervous 5- HT synthesis, which is achieved by acute tryptophan depletion ( ATD) Moja-De , on memory function in young males with attention deficit hyperactivity disorder ( ADHD). Method Twenty-two male patients with ADHD (ages 9-15 years, mean 10.95 ± 1.17 years) received ATD, thus diminishing central nervous 5- HT synthesis, and a tryptophan-balanced amino acid load ( BAL) in a randomized, double-blind, within-subject, crossover design study. Approximately 1.7 h after administration of ATD/ BAL, verbal declarative memory was assessed using the 'Auditory Verbal-Learning-Test' ( AVLT). Results There were no significant effects of ATD administration on verbal declarative memory function. Conclusion In this study, changes in 5- HT neurotransmission were not associated with specific aspects of verbal declarative memory in young persons with ADHD. Future studies with healthy control groups that address effects of covarying attentional processes are warranted. [ABSTRACT FROM AUTHOR]

A response from the authors of the articles in the special issue of the journal dealing with acute tryptophan depletion methodology is presented.

Diminished synthesis of the neurotransmitter serotonin (5-HT) has been linked to disrupted impulse control in aversive contexts. However, the neural correlates underlying a serotonergic modulation of female impulsivity remain unclear. The present study investigated punishment-induced inhibition in healthy young women. Eighteen healthy female subjects (aged 20–31) participated in a double-blinded, counterbalanced, placebo-controlled, within subjects, repeated measures study. They were assessed on two randomly assigned occasions that were controlled for menstrual cycle phase. In a randomized order, one day, acute tryptophan depletion (ATD) was used to reduce 5-HT synthesis in the brain. On the other day, participants received a tryptophan-balanced amino acid load (BAL) as a control condition. Three hours after administration of ATD/BAL, neural activity was recorded during a modified Go/No-Go task implementing reward or punishment processes using functional magnetic resonance imaging (fMRI). Neural activation during No-Go trials in punishment conditions after BAL versus ATD administration correlated positively with the magnitude of central 5-HT depletion in the ventral and subgenual anterior cingulate cortices (ACC). Furthermore, neural activation in the medial orbitofrontal cortex (mOFC) and the dorsal ACC correlated positively with trait impulsivity. The results indicate reduced neural sensitivity to punishment after short-term depletion of 5-HT in brain areas related to emotion regulation (subgenual ACC) increasing with depletion magnitude and in brain areas related to appraisal and expression of emotions (mOFC and dorsal ACC), increasing with trait impulsivity. This suggests a serotonergic modulation of neural circuits related to emotion regulation, impulsive behavior, and punishment processing in females. [ABSTRACT FROM AUTHOR]