EEG microstate beta-band abnormalities in obsessive-compulsive disorder: Associations with disease symptoms and...

The objectives of this study are to describe the disease-specific characteristics of EEG microstates in obsessive-compulsive disorder (OCD) and to evaluate the effects of 1-Hz repetitive transcranial magnetic stimulation (rTMS) on both OCD symptoms and microstate characteristics by a randomized controlled trial (RCT).

Thirty-nine patients with OCD and 34 healthy controls (HCs) were included in the first study phase examining disease-specific differences in EEG microstate characteristics. Subsequently, all patients were included in a double-blind, randomized, and sham-controlled trial comparing microstate changes in response to active 1-Hz rTMS (n = 20) or sham rTMS N(n = 19) over the right pre-supplementary motor area (pre-SMA) for 15 consecutive days.

Microstate C (MS C) was stronger in the beta band at baseline among OCD patients compared to HCs, but these differences did not remain significant after correction for multiple comparisons. In the RCT, linear mixed-effects model revealed a significant group × time interaction for Y-BOCS scores, with greater symptom reduction following active rTMS compared to sham rTMS (P = 0.003). A significant group × time interaction was also found for beta-band microstate D (MS D). Post hoc tests showed that the active group exhibited significant post-treatment increase in MS D duration (P = 0.020) and coverage (P = 0.033) relative to the sham group. Additionally, within the sham group, changes in beta-band microstate dynamics were significantly associated with changes in Y-BOCS scores, suggesting a potential link between spontaneous brain activity and symptom improvement in the absence of active stimulation.

Patients with OCD exhibit a trend toward aberrant EEG microstates in the beta band. Administration of 1-Hz rTMS targeting the right pre-SMA can alleviate OCD symptoms and modulate beta-band microstate properties. Nonetheless, beta-band microstate dynamics may serve as state-sensitive neural markers of OCD, reflecting disease progression or spontaneous symptom fluctuations. Their clinical relevance in informing individualized or stratified neuromodulation strategies warrants further investigation.