How specific are inhibitory deficits to obsessive-compulsive disorder? A neurophysiological comparison with panic disorder

• We conducted the first ERP study of inhibition in obsessive-compulsive disorder (OCD) to include an anxious comparison group.
• Surprisingly, inhibitory deficits and ERP anomalies were very similar in OCD and panic disorder, although more severe in OCD.
• Neurobiological models of OCD may overestimate the presence of OCD-specific inhibitory deficits, due to the lack of clinical comparison groups in previous studies.

ObjectiveImpaired inhibition may perpetuate repetitive symptoms in obsessive-compulsive disorder (OCD), however OCD-specific deficits have yet to be established. We investigated neural correlates of inhibition in OCD vs. healthy and anxious controls.MethodsERPs and reaction times (RTs) were compared between participants with OCD (n = 20), panic disorder (PD; n = 20) and healthy controls (HCs; n = 20) during an adapted Go/NoGo task, which manipulated inhibitory difficulty.ResultsA classic P3 NoGo anteriorisation effect occurred across groups. Both clinical groups showed RT impairment, and similar topographical anomalies of several (P2, N2 and P3) ERP components. Notably, both clinical groups lacked the strong frontally maximal N2 component topography seen in the HCs, across stimuli. Additionally, with increasing inhibitory difficulty, N2 latency increased in HCs but not in the clinical groups.ConclusionsUnexpectedly, ERP and behavioural anomalies during inhibition in OCD were not qualitatively different to those in PD, but were generally more severe. Common general and inhibitory deficits may underlie intrusive mental phenomena in both conditions.SignificanceThis first ERP response inhibition study in OCD to include anxious controls disconfirmed hypotheses regarding OCD-specific inhibitory deficits, indicating the importance of comparing OCD to other conditions, to evaluate neurobiological models.