Transdiagnostic modulation of brain networks by electroconvulsive therapy in schizophrenia and major depression.

Major depressive disorder (MDD) and schizophrenia (SCZ) share neurobiological and clinical commonalities. Altered functional connectivity of large-scale brain networks has been associated with both disorders. Electroconvulsive therapy (ECT) has proven to be an effective treatment in severe forms of MDD and SCZ. However, the role of ECT on the modulation of the dynamics of brain networks is still unknown. In this study, we used resting state functional magnetic resonance imaging (rs-fMRI) to investigate functional connectivity in 16 pharmacoresistant patients with SCZ or MDD and a matched group of normal controls. Patients were scanned before and after right-sided unilateral ECT. Group spatial independent component analysis was carried out with a multiple analysis of covariance (MANCOVA) approach to estimate the effects of ECT treatment on intrinsic components (INs). Functional network connectivity (FNC) was calculated between pairs of INs. Patients had reduced connectivity within a striato-thalamic network in the thalamus as well as increased low frequency oscillations in a striatal network. ECT reduced low frequency oscillations (LFOs) on a striatal network along with increasing functional connectivity in the medial prefrontal cortex within the DMN. Following ECT treatment, the FNC of the executive network was reduced with the DMN and increased with the salience network, respectively. Our findings suggest transnosological effects of ECT on the connectivity of large-scale networks as well as at the level of their interplay. Furthermore, they support a transnosological approach for the investigation not only of the neural correlates of the disease but also of the brain mechanism of treatment of mental disorders.

Neuromodulation in response to electroconvulsive therapy in schizophrenia and major depression.

BACKGROUND: Electroconvulsive therapy (ECT) is one of the most effective treatments in severe and treatment-resistant major depressive disorder (MDD). ECT has been also shown to be effective in schizophrenia (SZ), particularly when rapid symptom reduction is needed or in cases of resistance to drug-treatment. However, its precise mechanisms of action remain largely unknown. OBJECTIVE/HYPOTHESIS: This study examined whether ECT exerts disorder-specific or unspecific modulation of brain structure and function in SZ and MDD. METHODS: We investigated neuromodulatory effects of right-sided unilateral ECT in pharmacoresistant patients with SZ or MDD. Magnetic resonance imaging was conducted before and after ECT to investigate treatment-related effects on brain structure and function. Imaging data were analyzed by means of Voxel Based Morphometry and Resting State Functional Connectivity (RSFC) methods. RESULTS: Right unilateral ECT induced transdiagnostic regional increases of limbic gray matter and modulations of neural coupling at rest. Structural effects were accompanied by a decrease in RSFC within temporoparietal, prefrontal and cortical midline structures, and an increase in hypothalamic RSFC. The extent of structural and functional change was partially inversely associated with the baseline measures. CONCLUSION: The present findings provide first evidence for transdiagnostic changes of brain structure together with modulation of brain function after ECT. The data indicate diagnosis-unspecific mechanisms of action with respect to regional gray matter volume and resting-state functional connectivity.

Structural network changes in patients with major depression and schizophrenia treated with electroconvulsive therapy.

Electroconvulsive therapy (ECT) is one of the most effective treatments in severe and treatment-resistant major depressive disorder (MDD). In schizophrenia (SZ), ECT is frequently considered in drug-resistant cases, as an augmentation of antipsychotic treatment or in cases when rapid symptom relief is indicated. Accumulating neuroimaging evidence suggests modulation of medial temporal lobe and prefrontal cortical regions in MDD by ECT. In SZ, ECT-effects on brain structure have not been systematically investigated so far. In this study, we investigated brain volume in 21 ECT-naïve patients (12 with MDD, 9 with SZ) who received right-sided unilateral ECT. Twenty-one healthy controls were included. Structural magnetic resonance imaging data were acquired before and after ECT. Healthy participants were scanned once. Source-based morphometry was used to investigate modulation of structural networks pre/post ECT. ECT had an impact on distinct structural networks in MDD and SZ. In both MDD and SZ SBM revealed a medial temporal lobe (MTL) network (including hippocampus and parahippocampal cortex) which showed a significant increase after ECT. The increase in MTL network strength was not associated with clinical improvement in either MDD or SZ. In SZ a lateral prefrontal/cingulate cortical network showed a volume increase after ECT, and this effect was accompanied by clinical improvement. These findings provide preliminary evidence for structural network change in response to ECT in MDD and SZ. The data suggest both diagnosis-specific and transdiagnostic ECT-effects on brain volume. In contrast to SZ, in MDD structural network modulation by ECT was not associated with clinical improvement.

Hippocampal and entorhinal cortex volume decline in cognitively intact elderly.

Studying the distribution and chronological sequence of brain morphological changes that occur in normal aging is crucial for understanding the mechanisms underlying these alterations and for distinguishing them from pathological processes. Whether the hippocampal formation is subjected to or spared from age-related shrinkage still remains controversial. We used magnetic resonance imaging (MRI) in order to assess hippocampal and entorhinal morphology in two population-based cognitively unimpaired cohorts (aged 53-55 years and 73-75 years, respectively) matched for gender, education, handedness, and apolipoprotein E status. Voxel-based morphometry (VBM-DARTEL) and shape analysis (FSL-FIRST) revealed significant bihemispheric age-related shrinkage of subiculum and cornu ammonis as well as of the entorhinal cortex (investigated with VBM only). The results lend further support to an effect of aging on medial temporal lobe morphology and thus may be of importance for the interpretation of structural imaging findings, especially in those diseases that are typically related to advancing age, as well as for the interpretation of functional imaging studies, where age-related differences in hippocampal activation may--to a locally varying degree--be explained by morphometric alterations.