Subcortical functioning in obsessive-compulsive disorder: An exploratory EEG coherence study

BACKGROUND: Given the paucity of quantitative EEG studies using coherence measures to understand the electrophysiological functional integrity of sub-cortical structures in obsessive-compulsive disorder, the current study was carried out. METHODS: We obtained EEG coherence values for 20 adult OCD patients (10 males; 10 females) and 19 appropriately matched healthy controls across delta (0.5-3.5 Hz), theta (4-7.5 Hz), alpha (8-12 Hz), beta1 (12.5-20 Hz) and beta2 (20.5-30 Hz) bands. As coherence between distant brain regions reflects physiological activities at sub-cortical neural networks, we chose EEG channels at four distant brain regions - anterior interhemispheric, posterior interhemispheric, fronto-temporal and fronto-occipital. RESULTS: In comparison to controls we found significant increase of theta band EEG coherence in the fronto-occipital region in OCD patients (P = 0.045) which did not correlate significantly with either medication status or disease severity. CONCLUSION: This EEG coherence study that suggests hyperactivity at subcortical circuitry in OCD patients is in agreement with existing neuro-imaging findings. Furthermore, this finding provides external validity for sub-cortical dysfunction hypothesis of OCD.