The Effect of Symptom Provocation on Brain Electrophysiology in OCD Patients: an EEG Study

Functional brain imaging and electrophysiological studies show abnormalities in the functioning of the brain in Obsessive-Compulsive Disorder patients. Other studies have shown reduction in these abnormalities after the successful treatment, indicating that the abnormalities are dependent on ‘state factors’ than ‘trait factors’. One of the important ‘state factor’ is the obsessive-compulsive symptoms experienced by these patients. This study seeks to evaluate that if the abnormalities are dependent on state factors, then provocation of the OCD symptoms should accentuate the abnormalities. The study recruited 41 OCD patients (Males = 23, Females = 18) from the inpatient and outpatient Services of NIMHANS, Bengaluru based on the inclusion and exclusion criteria. Electrophysiological (EEG) recordings was carried out using the 32 channel Electrocap based on 10–20 international system. For the analysis 28 electrodes were taken and these were collapsed to 3 cortical regions of Frontal, Centroparietal and Temporal. Recording was done during baseline (eyes closed and eyes open) and during symptom provocation (innocuous control stimulus and symptom provocation stimulus) conditions. The obtained EEG data was subjected to Power Spectrum Analysis (PSA) using Fast Fourier Transformation, which yielded values in 5 frequency bands (Delta, Theta, Alpha, Beta 1 and Beta 2). These values were subjected to the statistical analysis. The results showed no significant differences between baseline and symptom provocation conditions. The findings of the study concluded that electrophysiological abnormalities observed in Obsessive-Compulsive patients might be due to trait factors than the state factors.