title: No Tryptophan, Tyrosine and Phenylalanine Abnormalities in Children with Attention-Deficit/Hyperactivity Disorder.
abstract: BACKGROUND
  The aim of the current study was to explore the role of aromatic amino acids (AAAs) in blood in relation to attention-deficit/hyperactivity disorder (ADHD). Given their impact on the synthesis of serotonin and dopamine, decreased concentrations of the AAAs tryptophan, tyrosine and phenylalanine in blood may contribute to the expression of ADHD symptoms. Decreased AAA blood concentrations, in turn, may be related to lowered dietary protein intake or to abnormal AAA catabolism, as evidenced by increased urinary AAA concentrations.
  
  
  METHODS
  Eighty-three children with ADHD (75% males) and 72 typically developing (TD) children (51% males), aged 6 to 13 years, participated in the study. AAA concentrations were assessed in blood spots and an 18-hour urinary sample. A nutritional diary was filled out by parents to calculate dietary protein intake. Parent and teacher questionnaires assessed symptoms of ADHD, oppositional defiant disorder, conduct disorder, and autism spectrum disorder.
  
  
  RESULTS
  Children with ADHD showed normal AAA concentrations in blood spots and urine, as well as normal protein intake compared to controls. No associations between AAA concentrations and symptoms of ADHD or comorbid psychiatric disorders were found.
  
  
  CONCLUSIONS
  This study is the first to explore AAA metabolism in children with ADHD using a well-defined and relatively large sample. We found that AAA deficiencies are not related to ADHD. The results do not support treatment with AAA supplements in children with ADHD. Future studies regarding the cause of serotonin and dopamine alterations in ADHD should focus on other explanations, such as effects of altered transport of AAAs.
authors.affiliation: Clinical Neuropsychology section, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
authors.forename: Catharina Elisabeth
authors.initials: CE
authors.lastname: Bergwerff
authors.affiliation: Clinical Neuropsychology section, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
authors.forename: Marjolein
authors.initials: M
authors.lastname: Luman
authors.affiliation: Center for Pediatrics and Adolescent Medicine, Medical Center-University of Freiburg, Freiburg, Germany.|Department of Clinical Chemistry, VU University Medical Center Amsterdam, Amsterdam, the Netherlands.
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Blom
authors.affiliation: Clinical Neuropsychology section, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
authors.forename: Jaap
authors.initials: J
authors.lastname: Oosterlaan
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000097:blood* / Q000652:urine; D019958:Attention Deficit and Disruptive Behavior Disorders / Q000097:blood / Q000652:urine; D000067877:Autism Spectrum Disorder / Q000097:blood / Q000652:urine; D016022:Case-Control Studies; D002648:Child; D019955:Conduct Disorder / Q000097:blood / Q000652:urine; D004032:Diet; D004044:Dietary Proteins / Q000737:chemistry; D005260:Female; D006801:Humans; D008297:Male; D009426:Netherlands; D010649:Phenylalanine / Q000097:blood* / Q000652:urine; D011795:Surveys and Questionnaires; D014364:Tryptophan / Q000097:blood* / Q000652:urine; D014443:Tyrosine / Q000097:blood* / Q000652:urine
chemical_list: D004044:Dietary Proteins; D014443:Tyrosine; D010649:Phenylalanine; D014364:Tryptophan