Altered EEG lagged coherence during rest in obsessive-compulsive disorder.

Objective: Functional magnetic resonance imaging (fMRI) studies found alterations of functional connectivity in obsessive compulsive disorder (OCD). However, there is little knowledge about region of interest (ROI) based electroencephalogram (EEG) connectivity, i.e. lagged non-linear and linear coherence in OCD. Goal of this study was to compare these EEG measures during rest and at different vigilance stages between patients and healthy controls (HC).

Methods: A 15 min resting-state EEG was recorded in 30 unmedicated patients and 30 matched HC. Intracortical lagged non-linear coherence of the main EEG-frequency bands within a set of frontal ROIs and within the default mode network (DMN) were computed and compared using intracortical exact low resolution electromagnetic tomography (eLORETA) software.

Results: Lagged non-linear but not linear coherence was significantly decreased for patients in comparison to HC for the beta 2 frequency between frontal brain areas but not within the DMN. When analysing separate EEG-vigilance stages, only high vigilance stages yielded decreased frontal phase synchronisation at beta and theta frequencies.

Conclusions: The results underline an altered neuronal communication within frontal brain areas during rest in OCD.

Significance: These findings encourage further research on connectivity measures as possible biomarkers for physiological homogeneous subgroups.