Electroconvulsive therapy (ECT) stands as a vital therapeutic intervention for individuals grappling with major depressive disorder (MDD). Despite its clinical significance, the precise mechanisms through which ECT exerts its therapeutic effects in MDD remain an area of ongoing research. This study delves into the regional cerebral blood flow changes in MDD patients undergoing ECT, aiming to shed light on these mechanisms.
In this study, we enrolled twenty-four patients diagnosed with severe MDD alongside a control group of fourteen healthy individuals. The MDD patients underwent a course of eight ECT sessions, utilizing brief-pulse square-wave signals at bitemporal locations. To evaluate the fluctuations in regional cerebral blood flow before and after ECT treatment, we employed resting-state functional magnetic resonance imaging (rs-fMRI). Data acquisition was performed twice for each patient – before the first ECT session and after the completion of the eighth session. We then applied fractional amplitude of low-frequency fluctuations (fALFF) analysis to quantitatively assess alterations in regional brain activity.
Our findings revealed significant differences in brain activity between MDD patients before ECT (pre-ECT) and healthy controls. Specifically, pre-ECT patients exhibited increased fALFF in several brain regions including the cerebellum lobe, parahippocampal gyrus, fusiform gyrus, anterior cingulate gyrus, and thalamus when compared to healthy controls. Furthermore, comparing brain activity within the MDD group, we observed a significant reduction in fALFF post-ECT in regions such as the cerebellum anterior lobe, fusiform gyrus, insula, parahippocampal gyrus, middle frontal gyrus, and inferior frontal gyrus, relative to their pre-ECT state.
It’s important to acknowledge the limitations of our study. The data acquisition was limited to two rs-fMRI scans at specific time points – before the first and after the eighth ECT session. Conducting more frequent scans throughout the ECT treatment period could provide a more granular view of the dynamic changes in brain activity. Additionally, the sample size, particularly the number of healthy controls, was relatively modest. Larger studies with increased participant numbers are warranted to strengthen the robustness of these findings.
In conclusion, our study demonstrates that the fALFF in the cerebellum anterior lobe, fusiform gyrus, and parahippocampal gyrus in healthy controls and post-ECT patients is notably lower compared to pre-ECT MDD patients. This key observation suggests that ECT treatment effectively modulates brain activity in these specific areas in individuals with MDD, moving towards activity levels observed in healthy individuals. These findings contribute to our understanding of how ECT impacts brain function and underscores its therapeutic efficacy in major depressive disorder, highlighting the alterations in brain activity relevant to health diagnosis and treatment of depression.
