The structural and functional MRI study of graduate students with major depressive disorder and suicidal ideation

Using structural and functional magnetic resonance imaging (fMRI), this study aimed to compare the neuroimaging characteristics of a research group of major depressive disorder (MDD) patients with or without suicidal ideation (SI). 46 graduate students diagnosed with MDD underwent assessment using the Hamilton Depression Rating Scale-24 (HAMD-24) and the Beck Scale for SI (BSI). Based on the BSI assessment, 22 MDD patients with SI were included in the SI group, while 24 patients without SI were included in the non-SI group. Both groups underwent structural and fMRI scans, and voxel-based morphometry, amplitude of low-frequency fluctuations, and functional connectivity (FC) analyses were performed. Compared to the non-SI group, patients in the SI group showed reduced gray matter volume (GMV) in the left hippocampus. Furthermore, the SI group exhibited decreased amplitude of low-frequency fluctuations values in the right insula and right hippocampus. Finally, using the right insula and bilateral hippocampus as seed points for FC analysis, the SI group showed reduced FC values between the left hippocampus and bilateral superior frontal gyri, as well as the right anterior cingulate cortex (ACC). The FC values in the SI group between the right hippocampus and bilateral superior frontal gyrus, as well as bilateral anterior cingulate gyri were also decreased. The MDD graduate student with SI exhibits both structural and functional abnormalities in the hippocampus, along with decreased brain network functional connectivity between the hippocampus, ACC, and prefrontal cortex. Our study suggests that the left hippocampus serves as an important structural and functional basis for the generation of SI in the MDD graduate students.