title: Reduced activation in right lateral prefrontal cortex and anterior cingulate gyrus in medication-naïve adolescents with attention deficit hyperactivity disorder during time discrimination.
abstract: BACKGROUND
  Patients with attention deficit hyperactivity disorder (ADHD) under-perform when discriminating between durations differing by several hundred milliseconds. This function involves right prefrontal and anterior cingulate (AC) brain regions, which are structurally and functionally compromised in this patient group during executive tasks. We investigated the neuro-anatomical substrates mediating fine temporal discrimination in adolescents with ADHD compared with controls, using functional magnetic resonance imaging (fMRI).
  
  
  METHODS
  Twenty-one male medication-naïve adolescents aged 10-15 years with a DSM-IV diagnosis of ADHD (combined subtype) and without comorbid Axis I disorders (except conduct disorder) were compared to a group of 17 age- and IQ-matched healthy adolescents. Using fMRI on a 1.5T scanner, we compared brain activation and performance between adolescents with ADHD and controls during a time discrimination task contrasted with a temporal order task.
  
  
  RESULTS
  Despite comparable performance, patients with ADHD showed decreased activation in right dorsolateral and inferior prefrontal cortex and AC during time discrimination compared with controls.
  
  
  CONCLUSIONS
  Right hemispheric fronto-cingulate abnormalities in ADHD, previously observed during inhibitory and executive functions, are also associated with temporal perception. Furthermore, recruitment of medication-naïve patients precludes the possibility that deficits are attributable to stimulant exposure.
authors.affiliation: Centre for Social Genetic and Developmental Psychiatry, Institute of Psychiatry, King's College, London, UK. spjwabs@iop.kcl.ac.uk
authors.forename: Anna B
authors.initials: AB
authors.lastname: Smith
authors.forename: Eric
authors.initials: E
authors.lastname: Taylor
authors.forename: Michael
authors.initials: M
authors.lastname: Brammer
authors.forename: Rozmin
authors.initials: R
authors.lastname: Halari
authors.forename: Katya
authors.initials: K
authors.lastname: Rubia