Consistent with the notion that obsessive-compulsive disorder might be characterized by abnormal action monitoring (Pitman, 1987), Gehring and colleagues first reported that patients with OCD had increased ERNs compared to age-matched controls (Gehring, Himle, & Nisenson, 2000). This pattern of results has now been replicated (Johannes et al., 2001; Ruchsow, Gron et al., 2005), and consistent results have also been reported in children with both generalized anxiety disorder (GAD) and OCD (Hajcak et al., 2007; Ladouceur, Dahl, Birmaher, Axelson, & Ryan, 2006). Additionally, several fMRI studies have confirmed the findings of increased error-related brain activity in OCD patients (Fitzgerald et al., 2005; Maltby, Tolin, Worhunsky, O’Keefe, & Kiehl, 2005; Ursu, Stenger, Shear, Jones, & Carter, 2003). One study found increased ACC activity in both error and correct trials in OCD patients, signifying an overall hyperactivity in the ACC during response monitoring (Ursu et al., 2003); similar results were reported in an ERP study that showed both an increased ERN and CRN in high-OC subjects (Hajcak & Simons, 2002).
