EEG Topography and Tomography (LORETA) in Diagnosis and Pharmacotherapy of Depression

Abstract

Earlier investigations suggested an involvement of the right hemisphere and the left prefrontal cortex (PFC) in the pathogenesis of depression. This paper presents our own electroencephalographic (EEG) topography and low-resolution brain electromagnetic tomography (LORETA) data obtained in unmedicated depressed patients, and the effects of two representative drugs of non-sedative and sedative antidepressants, i.e., citalopram (CIT) and imipramine (IMI), as compared with placebo in normal subjects. Sixty female menopausal syndrome patients with the diagnosis of a depressive episode without psychotic symptoms as well as 30 healthy controls were investigated. Concerning the effects of antidepressants, normal healthy subjects received single oral doses of 20 mg CIT, 75 mg IMI and placebo p.o. A 3-min vigilance-controlled EEG and a 4-min resting EEG was recorded pre- and post-drug administration and analyzed by means of EEG mapping and LORETA. In the EEG mapping, depressed patients demonstrated a decrease in absolute power in all frequency bands, an augmentation of relative delta/theta and beta and a decrease in alpha activity as well as a slowing of the delta/theta centroid and an acceleration of the alpha and beta centroid, which suggests vigilance decrements. In the alpha asymmetry index, they showed right frontal hyper- and left frontal hypoactivation correlated with the Hamilton Depression Score (HAMD). LORETA predominantly revealed decreased power in the theta and alpha-1 frequency band. Negative correlations between theta power and the HAMD were observed in the ventro-medial PFC, the bilateral rostral anterior cingulate cortex (ACC) and the left insular cortex; between alpha-1 power and the HAMD in the right PFC. In the EEG mapping of antidepressants, 20 mg CIT showed mainly activating, 75 mg IMI partly sedative properties. LORETA revealed that CIT increased alpha-2, beta-1, beta-2 and beta-3 power more over the right than over the left hemisphere. However, also a left temporal and frontal delta increase was observed. In conclusion, EEG topography and tomography of depressed menopausal patients demonstrated a right frontal hyper- and left frontal hypoactivation in the alpha asymmetry index as well as a vigilance decrease, with a right-hemispheric preponderance. Within antidepressants at least 2 subtypes may be distinguished from the electrophysiological point of view, a non-sedative and a sedative. LORETA identifies cerebral generators responsible for the pathogenesis of depression as well as for the mode of action of antidepressants.

Structural Asymmetry of Dorsolateral Prefrontal Cortex Correlates with Depressive Symptoms: Evidence from Healthy Individuals and Patients with Major Depressive Disorder

“…More directly, EEG studies have indicated that depressed patients have a negative asymmetry index in alpha power, reflecting left frontal hypo-and right frontal hyper-activation. The more negative the asymmetry index in the frontal lobes, the more severe are the depressive symptoms [49]. The abnormal structural asymmetry of the DLPFC found in our study is consistent with the view that depression is associated with an inter-hemispheric imbalance.…”

Análisis de fuentes del EEG en pacientes tratados con estimulación magnética transcraneal a 5 Hz como tratamiento antidepresivo

“…Los incrementos en la densidad de corriente prevalecieron en las bandas alfa y theta, lo que coincide con los resultados observados en las MEBAs 20 y en algunos estudios con LORETA en pacientes deprimidos. 21 El objetivo del presente trabajo fue estudiar los cambios en las fuentes de EEG, según el método VARETA, en un grupo de pacientes con trastorno depresivo mayor que recibieron EMTr a 5Hz sobre la corteza prefrontal dorsolateral izquierda como tratamiento único o en combinación con escitalopram, un inhibidor selectivo de la recaptura de serotonina.…”

Biological Alterations in Depression

“…Responders and non-responders differ in QEEG measurements at rest and during taskoriented activities (Bruder et al, 2008). LORETA, which assesses activity of deeper cortical regions like ACC and orbitofrontal cortex (Pizzagalli et al, 2001), identifies cortical alterations in relation to depression and antidepressant response (Anderer et al, 2002;Saletu et al, 2010). Both cordance and LORETA require whole-head electrode montages for data collection, which entails up to 75 minutes of QEEG recording, limiting its clinical utility.…”