Objective To explore abnormalities in functional connectivity of the affective network (AN) in relapse of major depressive disorder (MDD) after antidepressant treatment combined with resting state functional connectivity analysis.Methods Eleven recurrent MDD subjects after treatment,seventeen non recurrent MDD subjects after treatment and seventy-two healthy controls underwent fMRI scan.The amygdala,the pallidum,the insular cortex and the anterior cingulate cortex of the AN were selected as the template.Group independent component analysis (ICA) was performed to decompose the fMRI images into spatially independent components and the independent component which fit this template best was selected as AN.Two-sample t-tests were performed to investigate the changes in functional connectivity of the AN.Finally,the right amygdala and the medial prefrontal cortex were defined as seed regions.Results Compared with healthy control subjects and non-recurrent MDD group,recurrent MDD group showed significantly increased functional connectivity in the right amygdala in AN(P＜0.001).Meanwhile,the functional connectivity between the right amygdala and the medial prefrontal cortex was significantly decreased in recurrent MDD group(P ＜0.05).Conclusion Abnormal resting-state functional connectivity of the right amygdala after antidepressant treatment in MDD was found,suggesting that altered amygdala functional connectivity may serve as a predicator of relapse of the MDD.

Objective To explore the effects of abnormal effective connectivity within the default mode network (DMN)in relapsed patients with major depressive disorder.Methods Resting-state functional magnetic resonance imaging (rs-fMRI)data were collected from 21 patients of first-episode depression and 16 patients with relapsed depression,and 37 matched healthy controls.The effective connectivity within the DMN was investigated with spectral dynamic causal modeling (spDCM)method.Results spDCM analysis showed that the effective connections from left parietal cortex(LPC)to right parietal cortex(RPC)and medial frontal cortex(mPFC)were significantly decreased,while the connection from posterior cingulate cortex(PCC)to mPFC was increased in patients of first episode depression compared to healthy controls.Furthermore,the connectivity between mPFC and LPC were enhanced in patients with recurrent depression compared withhealthy control subjects,as well as PCC.Meanwhile,the connectivity between mPFC and PCC was enhanced in patients with relapse depression compared with patients of first episode depression.Conclusion Both first-episode and relapsed patients demonstrated abnormal effective connectivity of LPC,implicating that abnormal LPC connectivity may be associated with the neural substrates of depression.In contrast,the patients with relapsed depression showed aberrant connectivity with the mPFC,suggesting that abnormal effective connectivity of the mPFC may play an important role in the relapse of depression.