title: A similar but distinctive pattern of impaired cortical excitability in first-episode schizophrenia and ADHD.
abstract: BACKGROUND
  First-episode schizophrenia (FE-SZ) and attention deficit hyperactivity disorder (ADHD) are both neuropsychiatric disorders associated with an impaired dopaminergic transmission. Though displaying different clinical phenotypes, a common pathophysiological pathway is discussed controversially. Several studies using transcranial magnetic stimulation (TMS) revealed abnormalities in human motor cortex excitability in both schizophrenia and ADHD patients. Studies on cortical excitability comparing these two diseases directly are lacking.
  
  
  METHODS
  In this study, a total of 94 subjects were analyzed. Twenty-five FE-SZ patients were directly compared with 28 ADHD patients and 41 healthy controls (HC). We investigated cortical excitability (inhibitory and facilitatory networks) with single- and paired-pulse TMS to the left and right motor cortex.
  
  
  RESULTS
  Compared to HC, FE-SZ/ADHD patients displayed an impaired cortical inhibition over the left hemisphere. Apart from an enhanced intracortical facilitation, FE-SZ patients did not differ compared to ADHD patients in the main outcome measures. Both patient groups presented a dysfunctional hemispheric pattern of cortical inhibition and facilitation in comparison with HC.
  
  
  CONCLUSIONS
  The results of this study indicate a pattern of cortical disinhibition and abnormal hemispheric balance of intracortical excitability networks in two different psychiatric diseases. These effects might be associated with an imbalance in GABAergic and dopaminergic transmission and might provide evidence for a common pathophysiological pathway of both diseases.
authors.affiliation: Department of Psychiatry and Psychotherapy, Georg August University, Göttingen, Germany.
authors.forename: Alkomiet
authors.initials: A
authors.lastname: Hasan
authors.forename: Marc
authors.initials: M
authors.lastname: Schneider
authors.forename: Thomas
authors.initials: T
authors.lastname: Schneider-Axmann
authors.forename: Diane
authors.initials: D
authors.lastname: Ruge
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Retz
authors.forename: Michael
authors.initials: M
authors.lastname: Rösler
authors.forename: Peter
authors.initials: P
authors.lastname: Falkai
authors.forename: Thomas
authors.initials: T
authors.lastname: Wobrock
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001289:Attention Deficit Disorder with Hyperactivity / Q000473:pathology*; D002540:Cerebral Cortex / Q000503:physiopathology*; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D009433:Neural Inhibition / Q000502:physiology*; D011930:Reaction Time; D012559:Schizophrenia / Q000473:pathology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult