title: Presupplementary motor area hyperactivity during response inhibition: a candidate endophenotype of obsessive-compulsive disorder.
abstract: OBJECTIVE
  Endophenotype studies of obsessive-compulsive disorder (OCD) may uncover heritable traits that are related to genetic susceptibility to OCD. Deficient response inhibition is a promising endophenotype of OCD, although its functional neural correlates have not been extensively studied. The authors sought to determine the functional neural correlates of response inhibition in a large sample of medication-free OCD patients and their unaffected siblings.
  
  
  METHODS
  Forty-one OCD patients, 17 of their siblings, and 37 matched healthy comparison subjects performed a stop-signal task during 3-T functional MRI. The stop-signal reaction time provided a behavioral measure of response inhibition. The neural correlates of response inhibition were assessed in a region-of-interest analysis that included the presupplementary motor area, inferior frontal gyrus, subthalamic nucleus, and inferior parietal cortex.
  
  
  RESULTS
  Patients with OCD had greater stop-signal reaction times relative to healthy comparison subjects. The numerical stop-signal reaction time difference between siblings and comparison subjects failed to reach significance. Both patients with OCD and their siblings showed greater activity in the left presupplementary motor area during successful inhibition relative to comparison subjects. Relative to both the comparison subjects and the siblings, patients with OCD showed decreased activity in the right inferior parietal cortex and inferior frontal gyrus. In patients and siblings, presupplementary motor area activity correlated negatively with stop-signal reaction time.
  
  
  CONCLUSIONS
  These findings suggest that presupplementary motor area hyperactivity is a neurocognitive endophenotype of OCD that is possibly related to inefficient neural processing within the presupplementary motor area itself. Patients with OCD further showed a state-dependent deficit in recruiting right inferior parietal cortex and inferior frontal gyrus, which may contribute to their inhibition deficit.
authors.affiliation: Departments of Psychiatry and Anatomy and Neuroscience, VU University Medical Center, Amsterdam, the Netherlands. st.dewit@vumc.nl
authors.forename: Stella J
authors.initials: SJ
authors.lastname: de Wit
authors.forename: Froukje E
authors.initials: FE
authors.lastname: de Vries
authors.forename: Ysbrand D
authors.initials: YD
authors.lastname: van der Werf
authors.forename: Danielle C
authors.initials: DC
authors.lastname: Cath
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: Heslenfeld
authors.forename: Eveline M
authors.initials: EM
authors.lastname: Veltman
authors.forename: Anton J L M
authors.initials: AJ
authors.lastname: van Balkom
authors.forename: Dick J
authors.initials: DJ
authors.lastname: Veltman
authors.forename: Odile A
authors.initials: OA
authors.lastname: van den Heuvel
mesh_terms: D000328:Adult; D058068:Endophenotypes; D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D007266:Inhibition, Psychological; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009483:Neuropsychological Tests; D009771:Obsessive-Compulsive Disorder / Q000503:physiopathology* / Q000523:psychology; D011569:Psychiatric Status Rating Scales; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*