Obsessive-compulsive disorder (OCD) is associated with increased engagement of frontal brain regions across multiple event-related potentials

Abstract

Background: Obsessive-compulsive disorder (OCD) is a psychiatric condition leading to significant distress and poor quality of life. Successful treatment of OCD is restricted by the limited knowledge about its pathophysiology. This study aimed to investigate the pathophysiology of OCD using electroencephalographic (EEG) event-related potentials (ERPs), elicited from multiple tasks to characterise disorder-related differences in underlying brain activity across multiple neural processes.

Methods: ERP data were obtained from 25 OCD patients and 27 age- and sex-matched healthy controls (HCs) by recording EEG during flanker and go/nogo tasks. Error-related negativity (ERN) was elicited by the flanker task, while N200 and P300 were generated using the go/nogo task. Primary comparisons of the neural response amplitudes and the topographical distribution of neural activity were conducted using scalp field differences across all time points and electrodes.

Results: Compared to HCs, the OCD group showed altered ERP distributions. Contrasting with the previous literature on ERN and N200 topographies in OCD where fronto-central negative voltages were reported, we detected positive voltages. Additionally, the P300 was found to be less negative in the frontal regions. None of these ERP findings were associated with OCD symptom severity.

Conclusions: These results indicate that individuals with OCD show altered frontal neural activity across multiple executive function-related processes, supporting the frontal dysfunction theory of OCD. Furthermore, due to the lack of association between altered ERPs and OCD symptom severity, they may be considered potential candidate endophenotypes for OCD.

Keywords: Electroencephalography; N200; error-related negativity; event-related potentials; obsessive–compulsive disorder.

Figure 1.

Go/nogo and flanker task designs. Note. All participants performed two blocks of both tasks, each consisting of 250 trials. Stimuli were presented for 250 ms and the intertrial interval for go/nogo and flanker tasks were 1000–1400 and 1300–1500 ms, respectively.

Figure 2.

Progression of participants through the study. Note. Flow diagram of participant progression through the study. The final analysis included 24 OCD and 26 HC participants for the flanker analysis and 25 OCD and 27 HC participants for the go/nogo analysis. OCD, obsessive–compulsive disorder; HC, healthy control; EEG, electroencephalography.

Figure 3.

Topographical consistency test outcomes for all groups and conditions. Note. (a) TCT outcome of both OCD and HC groups during the flanker task. The OCD group showed a brief period with a lack of consistency from 100 to 120 ms post-response. (b) TCT outcome of the go/nogo task during go trials: there was consistency in the signal throughout, except prior to the stimuli. (c) TCT outcome of the go/nogo task during nogo trials: there were two brief periods of deficient consistency from 153 to 157 ms and 211 to 220 ms. Some of these periods overlap the significant period of the ERN and N200, which might reflect a lack of consistent variability in the OCD group rather than an actual consistent difference between groups. GFP, global field potential; HC, healthy control; OCD, obsessive–compulsive disorder; TCT, topographical consistency test.

Figure 4.

TANOVA main group effect with the flanker task. Note. (a, d) p values of the between group comparison across the entire epoch of the flanker task. The green highlighted areas (a: −25 to 19 ms, d: 102–151 ms) reflect periods that exceed the duration control (38 ms) for multiple comparisons across time. (b, e) Averaged topographical maps for each group during the significant window. (c, f) t map for topography of the OCD group minus HC topography during the significant time window. OCD, obsessive–compulsive disorder; HC, healthy control; TANOVA, topographical analysis of variance).

Figure 5.

TANOVA main group effect with the go/nogo task. Note. (a, d) p values of the between group comparison across the entire epoch of the go/nogo task. The green highlighted areas (a: 182–230 ms, d: 272–323 ms) reflect periods that exceed the duration control (44 ms) for multiple comparisons across time. (b, e) Averaged topographical maps for each group during the significant window. (c, f) t map for topography of the OCD group minus healthy control topography during the significant time window. OCD, obsessive–compulsive disorder; HC, healthy control; TANOVA, topographical analysis of variance.