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Association of QEEG Findings with Clinical Characteristics of OCD: Evidence of Left Frontotemporal Dysfunction

Objective: Our objectives were 1) to determine hemispheric asymmetry and regional differences on the EEGs of patients with obsessive–compulsive disorder (OCD); and 2) to investigate the effects of sex, treatment response, illness duration, and Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores on quantitative electroencephalographic (QEEG) measurements. Method: We recorded EEGs (12-channel) from 22 unmedicated patients with OCD but no depression and from 20 age- and sex-matched control subjects. All patients and control subjects underwent detailed neurological and psychiatric evaluations including the Hamilton Depression Rating Scale (HDRS) and Y-BOCS. Results: QEEG revealed higher frequencies of slow-wave bands and lower frequencies of alpha activity at predominantly left frontotemporal localization in patients with OCD, compared with control subjects. Analysis of variance of QEEG parameters and clinical characteristics showed that sex had a significant effect on delta and alpha frequencies of frontotemporal areas during hyperventilation (HV). Increasing total Y-BOCS score correlated positively with increased frequencies of right parietal delta activity and decreased frequencies of right frontotemporal alpha activity during HV. A significantly increased left frontal slow-wave activity and decreased beta activity during HV in treatment responders led us to consider that frontal lobe functions were better in this group of patients. Illness duration had no important effect on QEEG. Conclusion: Patients with OCD showed important frontotemporal dysfunction, predominantly in the left hemisphere. This was particularly evident in female subjects and in treatment responders. QEEG may be beneficial in understanding the neurobiological basis of OCD.