title: Catechol-O-methyltransferase valine158methionine polymorphism moderates methylphenidate effects on oppositional symptoms in boys with attention-deficit/hyperactivity disorder.
abstract: BACKGROUND
  The catechol-O-methyltransferase enzyme plays a key role in the function of prefrontal cortex, accounting for most of the degradation of dopamine. Previous studies have documented the improvement of oppositional symptoms in attention-deficit/hyperactivity disorder (ADHD) patients with methylphenidate (MPH) treatment. However, the effect of the COMT gene in the response to MPH on oppositional symptoms has not been investigated.
  
  
  METHODS
  A total of 251 children with ADHD fulfilled inclusion criteria to participate in the study. Dosages of short-acting MPH were augmented until no further clinical improvement was detected or until there were significant adverse events (MPH dose always > .3 mg/kg/day). The outcome measure was the parent-rated oppositional subscale of the Swanson, Nolan and Pelham Scale-Version IV (SNAP-IV). The scale was applied by child psychiatrists blinded to genotype at baseline and in the first and third months. The COMT valine158methionine polymorphism was genotyped by polymerase chain reaction based methods.
  
  
  RESULTS
  We detected significant improvement in SNAP-IV oppositional scores from baseline to the first and three months of treatment [n = 112; F(2,231) = 5.35, p = .005]. A significant effect of the presence of methionine allele in oppositional defiant disorder scores during treatment [F(1,148) = 5.02, p = .027] and a significant interaction between the methionine allele and treatment over time for the SNAP-IV oppositional scores during this period of treatment [F(2,229) = 6.40, p = .002] were both observed.
  
  
  CONCLUSIONS
  These results suggest an effect of the COMT genotype on the trajectory of oppositional defiant disorder symptoms improvement with MPH treatment in boys with ADHD.
authors.affiliation: Genetics Department, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Angélica
authors.initials: A
authors.lastname: Salatino-Oliveira
authors.forename: Julia P
authors.initials: JP
authors.lastname: Genro
authors.forename: Cristian
authors.initials: C
authors.lastname: Zeni
authors.forename: Guilherme V
authors.initials: GV
authors.lastname: Polanczyk
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Chazan
authors.forename: Ana P
authors.initials: AP
authors.lastname: Guimarães
authors.forename: Sidia M
authors.initials: SM
authors.lastname: Callegari-Jacques
authors.forename: Luis A
authors.initials: LA
authors.lastname: Rohde
authors.forename: Mara H
authors.initials: MH
authors.lastname: Hutz
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000187:drug effects / Q000502:physiology; D000483:Alleles; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics*; D002394:Catechol O-Methyltransferase / Q000235:genetics*; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D002648:Child; D002652:Child Behavior / Q000187:drug effects / Q000502:physiology; D002675:Child, Preschool; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use*; D020641:Polymorphism, Single Nucleotide
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate; D002394:Catechol O-Methyltransferase