Brain structural alterations in MDD patients with gastrointestinal symptoms: Evidence from the REST-meta-MDD project.

OBJECTIVE: While gastrointestinal (GI) symptoms are very common in patients with major depressive disorder (MDD), few studies have investigated the neural basis behind these symptoms. In this study, we sought to elucidate the neural basis of GI symptoms in MDD patients by analyzing the changes in regional gray matter volume (GMV) and gray matter density (GMD) in brain structure. METHOD: Subjects were recruited from 13 clinical centers and categorized into three groups, each of which is based on the presence or absence of GI symptoms: the GI symptoms group (MDD patients with at least one GI symptom), the non-GI symptoms group (MDD patients without any GI symptoms), and the healthy control group (HCs). Structural magnetic resonance images (MRI) were collected of 335 patients in the GI symptoms group, 149 patients in the non-GI symptoms group, and 446 patients in the healthy control group. The 17-item Hamilton Depression Rating Scale (HAMD-17) was administered to all patients. Correlation analysis and logistic regression analysis were used to determine if there was a correlation between the altered brain regions and the clinical symptoms. RESULTS: There were significantly higher HAMD-17 scores in the GI symptoms group than that of the non-GI symptoms group (P < 0.001). Both GMV and GMD were significant different among the three groups for the bilateral superior temporal gyrus, bilateral middle temporal gyrus, left lingual gyrus, bilateral caudate nucleus, right Fusiform gyrus and bilateral Thalamus (GRF correction, cluster-P < 0.01, voxel-P < 0.001). Compared to the HC group, the GI symptoms group demonstrated increased GMV and GMD in the bilateral superior temporal gyrus, and the non-GI symptoms group demonstrated an increased GMV and GMD in the right superior temporal gyrus, right fusiform gyrus and decreased GMV in the right Caudate nucleus (GRF correction, cluster-P < 0.01, voxel-P < 0.001). Compared to the non-GI symptoms group, the GI symptoms group demonstrated significantly increased GMV and GMD in the bilateral thalamus, as well as decreased GMV in the bilateral superior temporal gyrus and bilateral insula lobe (GRF correction, cluster-P < 0.01, voxel-P < 0.001). While these changed brain areas had significantly association with GI symptoms (P < 0.001), they were not correlated with depressive symptoms (P > 0.05). Risk factors for gastrointestinal symptoms in MDD patients (p < 0.05) included age, increased GMD in the right thalamus, and decreased GMV in the bilateral superior temporal gyrus and left Insula lobe. CONCLUSION: MDD patients with GI symptoms have more severe depressive symptoms. MDD patients with GI symptoms exhibited larger GMV and GMD in the bilateral thalamus, and smaller GMV in the bilateral superior temporal gyrus and bilateral insula lobe that were correlated with GI symptoms, and some of them and age may contribute to the presence of GI symptoms in MDD patients.

Abnormal functional connectivity with mood regulating circuit in unmedicated individual with major depression: a resting-state functional magnetic resonance study.

BACKGROUND: Reports on mood regulating circuit (MRC) indicated different activities between depressed patients and healthy controls. The functional networks based on MRC have not been described in major depression disorder (MDD). Both the anterior cingulate cortex (ACC) and thalamus are all the key regions of MRC. This study was to investigate the two functional networks related to ACC and thalamus in MDD. METHODS: Sixteen patients with MDD on first episode which never got any medication and sixteen matched health controls were scanned by 3.0 T functional magnetic resonance imaging (fMRI) during resting-state. The pregenual anterior cingulate cortex (pgACC) was used as seed region to construct the functional network by cortex section. The thalamus was used as seed region to construct the functional network by limbic section. Paired-t tests between-groups were performed for the seed-target correlations based on the individual fisher z-transformed correlation maps by SPM2. RESULTS: Depressed subjects exhibited significantly great functional connectivity (FC) between pgACC and the parahippocampus gyrus in one cluster (size 923) including left parahippocampus gyrus (-21, -49, 7), left parietal lobe (-3, -46, 52) and left frontal lobe (-27, -46, 28). The one cluster (size 962) of increased FC on thalamus network overlapped the precuneus near to right parietal lobe (9, -52, 46) and right cingulate gyrus (15, -43, 43) in health controls. CONCLUSIONS: Abnormal functional networks exist in earlier manifestation of MDD related to MRC by both cortex and limbic sections. The increased functional connectivity of pgACC and decreased functional connectivity of thalamus is mainly involved in bias mood processing and cognition.

Decreased regional homogeneity in major depression as revealed by resting-state functional magnetic resonance imaging.

BACKGROUND: Functional imaging studies indicate abnormal activities in cortico-limbic network in depression during either task or resting state. The present work was to explore the abnormal spontaneous activity shown with regional homogeneity (ReHo) in depression by resting-state functional magnetic resonance imaging (fMRI). METHODS: Using fMRI, the differences of regional brain activity were measured in resting state in depressed vs. healthy participants. Sixteen participants firstly diagnosed with major depressive disorder and 16 controls were scanned during resting state. A novel method based on ReHo was used to detect spontaneous hemodynamic responses across the whole brain. RESULTS: ReHo in the left thalamus, left temporal lobe, left cerebellar posterior lobe, and the bilateral occipital lobe was found to be significantly decreased in depression compared to healthy controls in resting state of depression. CONCLUSIONS: Abnormal spontaneous activity exists in the left thalamus, left temporal lobe, left cerebellar posterior lobe, and the bilateral occipital lobe. And the ReHo may be a potential reference in understanding the distinct brain activity in resting state of depression.