title: The effects of acute tryptophan depletion on reactive aggression in adults with attention-deficit/hyperactivity disorder (ADHD) and healthy controls.
abstract: BACKGROUND
  The neurotransmitter serotonin (5-HT) has been linked to the underlying neurobiology of aggressive behavior, particularly with evidence from studies in animals and humans. However, the underlying neurobiology of aggression remains unclear in the context of attention-deficit/hyperactivity disorder (ADHD), a disorder known to be associated with aggression and impulsivity. We investigated the effects of acute tryptophan depletion (ATD), and the resulting diminished central nervous serotonergic neurotransmission, on reactive aggression in healthy controls and adults with ADHD.
  
  
  RESULTS
  Twenty male patients with ADHD and twenty healthy male controls were subjected to ATD with an amino acid (AA) beverage that lacked tryptophan (TRP, the physiological precursor of 5-HT) and a TRP-balanced AA beverage (BAL) in a double-blind, within-subject crossover-study over two study days. We assessed reactive aggression 3.25 hours after ATD/BAL intake using a point-subtraction aggression game (PSAG) in which participants played for points against a fictitious opponent. Point subtraction was taken as a measure for reactive aggression. Lowered rates of reactive aggression were found in the ADHD group under ATD after low provocation (LP), with controls showing the opposite effect. In patients with ADHD, trait-impulsivity was negatively correlated with the ATD effect on reactive aggression after LP. Statistical power was limited due to large standard deviations observed in the data on point subtraction, which may limit the use of this particular paradigm in adults with ADHD.
  
  
  CONCLUSIONS
  Together with previous findings, the data provide preliminary evidence of an inverse association between trait-impulsivity and the ATD effect on reactive aggression after LP (as assessed by the PSAG) in patients with ADHD and that this relationship can be found in both adolescents and adults. Because of limited statistical power larger sample sizes are needed to find main effects of ATD/BAL administration on reactive aggression in adults with ADHD.
authors.affiliation: Department of Psychiatry and Psychotherapy, LVR-Clinics Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Zimmermann
authors.forename: Marco
authors.initials: M
authors.lastname: Grabemann
authors.forename: Christian
authors.initials: C
authors.lastname: Mette
authors.forename: Mona
authors.initials: M
authors.lastname: Abdel-Hamid
authors.forename: Jennifer
authors.initials: J
authors.lastname: Uekermann
authors.forename: Jennifer
authors.initials: J
authors.lastname: Ueckermann
authors.forename: Markus
authors.initials: M
authors.lastname: Kraemer
authors.forename: Jens
authors.initials: J
authors.lastname: Wiltfang
authors.forename: Bernhard
authors.initials: B
authors.lastname: Kis
authors.forename: Florian Daniel
authors.initials: FD
authors.lastname: Zepf
mesh_terms: D000328:Adult; D000374:Aggression / Q000523:psychology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000178:diet therapy* / Q000523:psychology*; D001628:Beverages; D016022:Case-Control Studies; D006801:Humans; D008297:Male; D014364:Tryptophan / Q000008:administration & dosage / Q000172:deficiency*
chemical_list: D014364:Tryptophan