BACKGROUND: Standardized low-resolution electromagnetic tomography (sLORETA) is a new quantitative EEG method for determining distribution of neuronal electrical activity in the form of three-dimensional images of current density of the cerebral cortex. Unlike standard quantitative EEG, it allows noninvasive and detailed localization of neuronal generators responsible for surface EEG with zero localization error. The study aimed at finding electrotomographic differences between patients with panic disorder who respond well to cognitive behavioral therapy (CBT) and those with an inadequate response and to determine factors predicting a response to treatment.
METHODS: The study comprised 24 patients diagnosed with panic disorder with or without agoraphobia (ICD-10 F41.0). The severity of symptoms was measured with the Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI), Sheehan Anxiety Scale, subjective and objective Clinical Global Impression (CGI) and Dissociative Experiences Scale (DES). Additionally, quality of life was evaluated using the Q-LES-Q questionnaire. Based on final BAI score decreases by 25%, the patients were classified into two groups - responders and non-responders. 21-channel EEGs were recorded at baseline and after completion of therapy. Power spectra and intracortical tomography were computed by sLORETA in seven frequency bands and compared between (responders vs. non-responders) and within (pre- vs. post-treatment) groups.
RESULTS: There were no differences between responders and non-responders with respect to age, gender and baseline disorder symptomatology. Statistical analysis of sLORETA values demonstrated no significant inter-group differences in the pretreatment current density distribution. After treatment, only responders showed a significant decrease of alpha-2 sources (p<0.05) in the occipital lobes and cuneus and a statistical trend for increased beta-3 sources (p<0.10) in the posterior cingulate. In non-responders, there were no statistically significant changes in sLORETA findings following therapy.
CONCLUSIONS: The study failed to use pretreatment sLORETA in the prediction of therapeutic response in patients with panic disorder. However, we clearly demonstrated that only treatment response was associated with significant changes of electric neuronal activity. An analysis of demographic data suggested that duration of the disease, age, level of dissociation and employment may be considered as factors influencing the response.