Increases in Regional Brain Volume and Thickness Following ECT and Relationships With Changes in Depressive Symptoms and Peripheral Inflammation

OBJECTIVES: Treatment-resistant depression (TRD) is highly prevalent and debilitating. Electroconvulsive therapy (ECT) is an efficacious intervention for TRD. This study sought to clarify ECT's mechanisms by examining relationships between ECT-induced changes in regional brain volume and in peripheral inflammatory markers in TRD, and associations between these structural neural changes and clinical outcomes. METHODS: Volume/thickness of 8 corticolimbic regions of interest (ROIs) were identified before and after index series ECT in n=44 TRD subjects. Changes in ROI size were assessed using MANCOVA in TRD compared with healthy controls. Regressions within TRD then assessed ROI changes in association with changes in IL-6 and CRP, and changes in symptoms of depression. RESULTS: Following ECT, the bilateral hippocampus, amygdala, striatum, and ACC, and left insula, DLPFC, and DMPFC, were found to be increased in TRD relative to baseline. Within TRD, these increases were not associated with any longitudinal changes in inflammatory markers that occurred during the course of treatment. Increases in the hippocampus, DLPFC, DMPFC, and OFC predicted improvement in affective symptoms of depression. Increased DLPFC thickness also predicted improvement in cognitive symptoms of depression. CONCLUSIONS: Although we previously found that changes in inflammatory measures were associated with changes in affective and cognitive symptoms of depression, just as DLPFC and DMPFC increases were, these biomarkers were not associated with each other. It is possible that these processes relate to clinical effects of ECT through independent or distally related means, although further research is required.