Magnetic seizure therapy modulates default mode network fluctuations of major depressive disorder

Objective To observe the change of functional connectivity(FC) between default mode network(DMN)and the other brain regions in patients with depression before and after magnetic seizure therapy(MST), and explore the role of DMN in therapeutic mechanism of MST. Methods Fifteen patients with depression who met the criteria of enrollment underwent rs-fMRI scanning before and after the MST treatments.As a very important region of DMN, the posterior cingulate cortex(PCC) was selected as the region of interest(ROI)to make the functional connectivity analysis with other brain regions, then the differences in FC before and after MST treatments were tested.The correlation of FC index changes with the score changes of HAMD-17 and five factors of HAMD-17 was analyzed after MST treatments. Results A comparison of the differences in DMN before and after treatments showed that the connection between left PCC and bilateral medial temporal lobe connectivity decreased significantly(left: MNI: x, y, z=-66, -39, -15, right: MNI: x, y, z=69, -30, -6)(P<0.05). The connection between left PCC with left cerebellum (MNI: x, y, z=-33, -42, -42)and left occipital lobe(MNI: x, y, z=0, -84, 24)significantly increased(P<0.05). The changes of sleep factor of HAMD-17 were positively correlated with the functional connectivity changes of bilateral medial temporal lobe (left: r=0.670, P=0.006; right: r=0.570, P=0.026), but negatively correlated with the functional connectivity changes of the left cerebellum (r=-0.543, P=0.037). Conclusion MST can play an antidepressant role by regulating DMN functional connection of depressive patients and it may be a neuromodulation mechanism of MST in the treatment of depression. Key words: Major depressive disorder; Magnetic seizure therapy; Default mode network; Functional connectivity