Objective: To examine the brain effects of transcutaneous auricular vagus nerve stimulation (taVNS) treatment of recurrent depression based on the functional brain network by using resting-state functional magnetic resonance imaging (fMRI).
Methods: Twenty-five patients with recurrent depression were enrolled in a single-arm trial of taVNS treatment for eight weeks. Clinical results were assessed by 17-item Hamilton Depression Rating Scale (HAMD-17), Hamilton Anxiety Scale (HAMA), Self-Rating Depression Scale (SDS), Self-Rating Anxiety Scale (SAS), and Ruminative Response Scale (RRS) scales. Resting-state fMRI was conducted to explore the brain effects before and after treatment. For the functional connectivity (FC) analysis, the bilateral nucleus accumbens, globus pallidus, caudate, and putamen were selected as seeds. Finally, the correlations between FC and the clinical scale scores were calculated.
Results: After treatment, the patients' scores of HAMD-17, HAMA, SDS, SAS, and RRS were significantly decreased ( < 0.05). FC was considerably decreased between the following areas: the left globus pallidus and the right postcentral gyrus, inferior parietal gyrus, the right globus pallidus and the left superior marginal gyrus, postcentral gyrus, superior parietal gyrus, inferior parietal gyrus, precuneus, right postcentral gyrus, superior marginal gyrus, and inferior parietal gyrus, between the right caudate and the right lingual gyrus, calcarine gyrus, and cerebellum. Changes in FC between the right globus pallidus and the left inferior parietal gyrus, between the left globus pallidus and the right postcentral gyrus were negatively correlated with HAMD-17 scores change before and after treatment (before, = 0.003, = -0.6; after, 0.009,= -0.54). The change of FC between the right globus pallidus and the right postcentral gyrus was negatively correlated with the change in SDS (= 0.026,= -0.474). The difference in FC between the right globus pallidus and the right postcentral gyrus was negatively correlated with the change in SAS (= 0.016,= -0.513).
Conclusions: Recurrent depression could be effectively treated with taVNS. The changes in brain FC involving the basal ganglia, default mode, and sensorimotor networks provide insight into the effects of taVNS treatment on recurrent depression.
Keywords: basal ganglia; default mode network; depression; magnetic resonance imaging; recurrence; transcutaneous auricular vagus nerve stimulation.