Electroconvulsive Therapy For Depression: A Resting-state Functional Magnetic Resonance Imaging Study

Background Electroconvulsive therapy(ECT) is an important treatment option for depression in clinical practice. Compared to antidepressant drugs, ECT has a more rapid onset and is also effective for treatment-resistant depression patients. But ECT could cause cognitive impairment and other side effects, which limit its promotion and application. However, little is known about the underlying therapeutic mechanisms of ECT, even though ECT has been applied in clinical practice for over 70 years. Exploring the therapeutic mechanisms of ECT for depression can further illuminate the pathogenesis of depression, improve the ECT technique to increases therapeutic effect and reduce side effects, and contribute to develop new treatment method for depression.Objective To observe the change of depression before and after ECT with the method of resting-state functional magnetic resonance imaging(rs-f MRI), and explore the therapeutic mechanisms of ECT for depression.(1) Considerable evidence suggests that depression is related to interhemispheric functional coordination deficits. The aim of this study was to explore the impact of ECT on the interhemispheric functional coordination in depression patients.(2) A lot of studies highlights the role of amygdala-prefrontal circuit in emotion regulation, and current opinion holds that amygdala-prefrontal circuit underlying emotion processing are abnormal in depression. The aim of this study was to observe the change of functional connectivity between amygdala and prefrontal cortex in depression patients before and after ECT, and explore the role of amygdala-prefrontal circuit in therapeutic mechanism of ECT.Methods(1) We used resting-state functional magnetic resonance imaging to observe the change of interhemispheric functional coordination with the method of voxel-mirrored homotopic connectivity(VMHC) in 11 depressed patients before and after ECT, compared with 15 healthy controls.(2) We set the bilateral amygdale as the seeds respectively, and observe the change of functional connectivity between amygdala and prefrontal cortex in 18 depression patients before and after ECT, compared with 20 healthy controls.Results(1) The results showed that, compared with depression patients before ECT, VMHC was significantly increased in superior frontal gyri(BA 8), middle frontal gyri(two clusters: BA 8/9 and BA 10) and angular gyri(BA 39) in depression patients after ECT. Compared with healthy controls, VMHC in those areas was significantly lower in the middle frontal gyri(BA 8/9) and angular gyri(BA 39) in depression patients before ECT, but no significant difference was observed in the superior frontal gyri(BA 8) and middle frontal gyri(BA 10). There was no significant correlation between the changes of 17-item Hamilton Depression Rating Scale(HAMD) and changed VMHC values in those four areas in depression patients.(2) The results showed that, compared with depression patients before ECT, the functional connectivity between left amgydala and left lateral frontopolar cortex(BA 10), left amgydala and right lateral frontopolar cortex(BA 10), right amygdala and right medial prefrontal cortex(BA 10) were significantly increased in depression patients after ECT. Compared with healthy controls, the functional connectivity between left amgydala and left lateral frontopolar cortex(BA 10), left amgydala and right lateral frontopolar cortex(BA 10), right amygdala and right medial prefrontal cortex(BA 10) were significantly lower in depression patients before ECT. There was no significant difference of the functional connectivity in these areas between depression patients after ECT and healthy controls. The change of functional connectivity between left amgydala and right lateral frontopolar cortex(BA 10) was significantly correlated with the change of 17-HAMD in depression patients before and after ECT.Conclusion(1) The results suggest that ECT selectively modulated interhemispheric functional coordination in depression patients, which may play an important mechanistic role in the treatment of depression.(2) The results suggest that ECT could improve the abnormality of amygdale-prefrontal cortex in depression patients, which may contribute to the therapeutic mechanisms of ECT for depression.All the results of these studies further illuminate the pathogenesis of depression, and preliminary implicated the therapeutic mechanisms of ECT for depression, which may contribute to improve the ECT technique and develop new treatment method for depression.