Low resolution electromagnetic tomography (LORETA) and SSRI response in obsessive-compulsive disorder

Neuroimaging studies in obsessive-compulsive disorder (OCD) have shown that distinctive brain activity patterns might serve as predictors of patients treatment response. In our study we used EEG and Low Resolution Electromagnetic Tomography (LORETA) to investigate whether brain electrical activity is different in responders and nonresponders. 41 drug-free patients with OCD were included and received EEG recordings before treatment with sertraline. Response was defined as a >50% reduction in the Yale-Brown-Obsessive-Compulsive-Scale (YBOCS) at week 10. EEG was analysed using LORETA with cross spectrum analyses for the delta, theta, alpha, and beta frequency bands. Regional differences of brain electrical activity were investigated with a region-of-interest (ROI) analysis for the rostral anterior cingulate cortex (ACC). Responders showed significantly lower activities in the beta1 (T=2.86, p<0.05), beta2 (T=2.81, p<0.05) and beta3 (T=2.76, p<0.05) frequency bands, especially in the frontal and parietal lobes. ROI analyses of the rostral ACC also revealed a lower activity in the alpha2 (T=2.06, p<0.05), beta1 (T=2.06, p=0.05), and beta2 (T=2.04, p=0.05) frequency bands in treatment responders. Our study showed reduced brain electrical activities in the group of responders, predominantly within beta frequency bands. The data suggest that a distinctive pattern of activity within frontal brain regions might help to predict drug response in patients with OCD.

This study was supported by Pfizer