No effect of acute tryptophan depletion on verbal declarative memory in young persons with ADHD
F. D. Zepf, Translational Neuroscience in Psychiatry and Neurology, Clinic for Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, RWTH Aachen University, JARA Translational Brain Medicine, Neuenhofer Weg 21, 52074 Aachen, Germany.
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 [1, 2], on memory function in young males with attention deficit hyperactivity disorder (ADHD).
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).
There were no significant effects of ATD administration on verbal declarative memory function.
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.