title: Intratask Variability As a Correlate for DRD4 and SLC6A3 Variants: A Pilot Study in ADHD.
abstract: Behavioral variability may be an ADHD key feature. Currently used ex-Gaussian/Fast Fourier Transform analyses characterize general distribution and oscillatory/rhythmic components of performance but are unable to demonstrate slow cumulative changes over entire tasks.
  
  
  OBJECTIVE
  To explore how performance of ADHD children and unaffected sibs gradually evolves in relation to genetic variants linked to ADHD.
  
  
  METHODS
  A total of 40 kids (20 ADHD-discordant sib pairs) between 8 and 13 years resolved a visual Go/NoGo with 10% NoGo probability. Variable number tandem repeats (VNTRs) at DRD4 and SLC6A3 were identified following standard protocols. Performance changes were assessed by linear/logistic mixed-effect models.
  
  
  RESULTS
  Models exploring SLC6A3 effects demonstrated less accentuated increments of response time (RT) (p = .046) and cumulative increments in the correct responses to "NoGo" (p = .00027) in 10R/10R participants. Models for DRD4 showed faster decline of correct responses to "Go" (p = .0078) in 2R/7R carriers.
  
  
  CONCLUSIONS
  Dynamical analysis of attention/inhibition measures may unravel new correlates to DRD4 and SLC6A3 variants.
authors.affiliation: Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Marcela
authors.initials: M
authors.lastname: Henríquez-Henríquez
authors.affiliation: Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Luis
authors.initials: L
authors.lastname: Villarroel
authors.affiliation: Universidad Mayor, Santiago, Chile.
authors.forename: Hugo
authors.initials: H
authors.lastname: Henríquez
authors.affiliation: Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Francisco
authors.initials: F
authors.lastname: Zamorano
authors.affiliation: Instituto de Alta Investigación, Universidad de Tarapacá, Arica, Chile.
authors.forename: Francisco
authors.initials: F
authors.lastname: Rothhammer
authors.affiliation: Pontificia Universidad Católica de Chile, Santiago, Chile faboitiz@puc.cl.
authors.forename: Francisco
authors.initials: F
authors.lastname: Aboitiz
mesh_terms: D000293:Adolescent; D001288:Attention / Q000502:physiology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics* / Q000503:physiopathology* / Q000523:psychology; D002648:Child; D050483:Dopamine Plasma Membrane Transport Proteins / Q000235:genetics*; D005260:Female; D008040:Genetic Linkage; D005838:Genotype; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D018598:Minisatellite Repeats / Q000235:genetics; D010865:Pilot Projects; D011930:Reaction Time / Q000235:genetics; D050638:Receptors, Dopamine D4 / Q000235:genetics*; D035781:Siblings; D013647:Task Performance and Analysis
chemical_list: C493599:DRD4 protein, human; D050483:Dopamine Plasma Membrane Transport Proteins; C493214:SLC6A3 protein, human; D050638:Receptors, Dopamine D4